use std::collections::HashSet; use bevy_ecs::prelude::*; use bevy_math::{Mat4, UVec2, UVec3, Vec2, Vec3, Vec3A, Vec3Swizzles, Vec4, Vec4Swizzles}; use bevy_reflect::prelude::*; use bevy_render::{ camera::{Camera, CameraProjection, OrthographicProjection}, color::Color, extract_resource::ExtractResource, primitives::{Aabb, CubemapFrusta, Frustum, Plane, Sphere}, render_resource::BufferBindingType, renderer::RenderDevice, view::{ComputedVisibility, RenderLayers, Visibility, VisibleEntities}, }; use bevy_transform::components::GlobalTransform; use bevy_utils::tracing::warn; use crate::{ calculate_cluster_factors, CubeMapFace, CubemapVisibleEntities, ViewClusterBindings, CLUSTERED_FORWARD_STORAGE_BUFFER_COUNT, CUBE_MAP_FACES, MAX_UNIFORM_BUFFER_POINT_LIGHTS, POINT_LIGHT_NEAR_Z, }; /// A light that emits light in all directions from a central point. /// /// Real-world values for `intensity` (luminous power in lumens) based on the electrical power /// consumption of the type of real-world light are: /// /// | Luminous Power (lumen) (i.e. the intensity member) | Incandescent non-halogen (Watts) | Incandescent halogen (Watts) | Compact fluorescent (Watts) | LED (Watts | /// |------|-----|----|--------|-------| /// | 200 | 25 | | 3-5 | 3 | /// | 450 | 40 | 29 | 9-11 | 5-8 | /// | 800 | 60 | | 13-15 | 8-12 | /// | 1100 | 75 | 53 | 18-20 | 10-16 | /// | 1600 | 100 | 72 | 24-28 | 14-17 | /// | 2400 | 150 | | 30-52 | 24-30 | /// | 3100 | 200 | | 49-75 | 32 | /// | 4000 | 300 | | 75-100 | 40.5 | /// /// Source: [Wikipedia](https://en.wikipedia.org/wiki/Lumen_(unit)#Lighting) #[derive(Component, Debug, Clone, Copy, Reflect)] #[reflect(Component, Default)] pub struct PointLight { pub color: Color, pub intensity: f32, pub range: f32, pub radius: f32, pub shadows_enabled: bool, pub shadow_depth_bias: f32, /// A bias applied along the direction of the fragment's surface normal. It is scaled to the /// shadow map's texel size so that it can be small close to the camera and gets larger further /// away. pub shadow_normal_bias: f32, } impl Default for PointLight { fn default() -> Self { PointLight { color: Color::rgb(1.0, 1.0, 1.0), /// Luminous power in lumens intensity: 800.0, // Roughly a 60W non-halogen incandescent bulb range: 20.0, radius: 0.0, shadows_enabled: false, shadow_depth_bias: Self::DEFAULT_SHADOW_DEPTH_BIAS, shadow_normal_bias: Self::DEFAULT_SHADOW_NORMAL_BIAS, } } } impl PointLight { pub const DEFAULT_SHADOW_DEPTH_BIAS: f32 = 0.02; pub const DEFAULT_SHADOW_NORMAL_BIAS: f32 = 0.6; } #[derive(Clone, Debug, Reflect)] #[reflect(Resource)] pub struct PointLightShadowMap { pub size: usize, } impl Default for PointLightShadowMap { fn default() -> Self { Self { size: 1024 } } } /// A Directional light. /// /// Directional lights don't exist in reality but they are a good /// approximation for light sources VERY far away, like the sun or /// the moon. /// /// Valid values for `illuminance` are: /// /// | Illuminance (lux) | Surfaces illuminated by | /// |-------------------|------------------------------------------------| /// | 0.0001 | Moonless, overcast night sky (starlight) | /// | 0.002 | Moonless clear night sky with airglow | /// | 0.05–0.3 | Full moon on a clear night | /// | 3.4 | Dark limit of civil twilight under a clear sky | /// | 20–50 | Public areas with dark surroundings | /// | 50 | Family living room lights | /// | 80 | Office building hallway/toilet lighting | /// | 100 | Very dark overcast day | /// | 150 | Train station platforms | /// | 320–500 | Office lighting | /// | 400 | Sunrise or sunset on a clear day. | /// | 1000 | Overcast day; typical TV studio lighting | /// | 10,000–25,000 | Full daylight (not direct sun) | /// | 32,000–100,000 | Direct sunlight | /// /// Source: [Wikipedia](https://en.wikipedia.org/wiki/Lux) #[derive(Component, Debug, Clone, Reflect)] #[reflect(Component, Default)] pub struct DirectionalLight { pub color: Color, /// Illuminance in lux pub illuminance: f32, pub shadows_enabled: bool, pub shadow_projection: OrthographicProjection, pub shadow_depth_bias: f32, /// A bias applied along the direction of the fragment's surface normal. It is scaled to the /// shadow map's texel size so that it is automatically adjusted to the orthographic projection. pub shadow_normal_bias: f32, } impl Default for DirectionalLight { fn default() -> Self { let size = 100.0; DirectionalLight { color: Color::rgb(1.0, 1.0, 1.0), illuminance: 100000.0, shadows_enabled: false, shadow_projection: OrthographicProjection { left: -size, right: size, bottom: -size, top: size, near: -size, far: size, ..Default::default() }, shadow_depth_bias: Self::DEFAULT_SHADOW_DEPTH_BIAS, shadow_normal_bias: Self::DEFAULT_SHADOW_NORMAL_BIAS, } } } impl DirectionalLight { pub const DEFAULT_SHADOW_DEPTH_BIAS: f32 = 0.02; pub const DEFAULT_SHADOW_NORMAL_BIAS: f32 = 0.6; } #[derive(Clone, Debug, Reflect)] #[reflect(Resource)] pub struct DirectionalLightShadowMap { pub size: usize, } impl Default for DirectionalLightShadowMap { fn default() -> Self { #[cfg(feature = "webgl")] return Self { size: 2048 }; #[cfg(not(feature = "webgl"))] return Self { size: 4096 }; } } /// An ambient light, which lights the entire scene equally. #[derive(Clone, Debug, ExtractResource, Reflect)] #[reflect(Resource)] pub struct AmbientLight { pub color: Color, /// A direct scale factor multiplied with `color` before being passed to the shader. pub brightness: f32, } impl Default for AmbientLight { fn default() -> Self { Self { color: Color::rgb(1.0, 1.0, 1.0), brightness: 0.05, } } } /// Add this component to make a [`Mesh`](bevy_render::mesh::Mesh) not cast shadows. #[derive(Component, Reflect, Default)] #[reflect(Component, Default)] pub struct NotShadowCaster; /// Add this component to make a [`Mesh`](bevy_render::mesh::Mesh) not receive shadows. #[derive(Component, Reflect, Default)] #[reflect(Component, Default)] pub struct NotShadowReceiver; #[derive(Debug, Hash, PartialEq, Eq, Clone, SystemLabel)] pub enum SimulationLightSystems { AddClusters, AssignLightsToClusters, UpdateDirectionalLightFrusta, UpdatePointLightFrusta, CheckLightVisibility, } // Clustered-forward rendering notes // The main initial reference material used was this rather accessible article: // http://www.aortiz.me/2018/12/21/CG.html // Some inspiration was taken from “Practical Clustered Shading” which is part 2 of: // https://efficientshading.com/2015/01/01/real-time-many-light-management-and-shadows-with-clustered-shading/ // (Also note that Part 3 of the above shows how we could support the shadow mapping for many lights.) // The z-slicing method mentioned in the aortiz article is originally from Tiago Sousa’s Siggraph 2016 talk about Doom 2016: // http://advances.realtimerendering.com/s2016/Siggraph2016_idTech6.pdf /// Configure the far z-plane mode used for the furthest depth slice for clustered forward /// rendering #[derive(Debug, Copy, Clone)] pub enum ClusterFarZMode { /// Calculate the required maximum z-depth based on currently visible lights. /// Makes better use of available clusters, speeding up GPU lighting operations /// at the expense of some CPU time and using more indices in the cluster light /// index lists. MaxLightRange, /// Constant max z-depth Constant(f32), } /// Configure the depth-slicing strategy for clustered forward rendering #[derive(Debug, Copy, Clone)] pub struct ClusterZConfig { /// Far z plane of the first depth slice pub first_slice_depth: f32, /// Strategy for how to evaluate the far z plane of the furthest depth slice pub far_z_mode: ClusterFarZMode, } impl Default for ClusterZConfig { fn default() -> Self { Self { first_slice_depth: 5.0, far_z_mode: ClusterFarZMode::MaxLightRange, } } } /// Configuration of the clustering strategy for clustered forward rendering #[derive(Debug, Copy, Clone, Component)] pub enum ClusterConfig { /// Disable light cluster calculations for this view None, /// One single cluster. Optimal for low-light complexity scenes or scenes where /// most lights affect the entire scene. Single, /// Explicit x, y and z counts (may yield non-square x/y clusters depending on the aspect ratio) XYZ { dimensions: UVec3, z_config: ClusterZConfig, /// Specify if clusters should automatically resize in x/y if there is a risk of exceeding /// the available cluster-light index limit dynamic_resizing: bool, }, /// Fixed number of z slices, x and y calculated to give square clusters /// with at most total clusters. For top-down games where lights will generally always be within a /// short depth range, it may be useful to use this configuration with 1 or few z slices. This /// would reduce the number of lights per cluster by distributing more clusters in screen space /// x/y which matches how lights are distributed in the scene. FixedZ { total: u32, z_slices: u32, z_config: ClusterZConfig, /// Specify if clusters should automatically resize in x/y if there is a risk of exceeding /// the available cluster-light index limit dynamic_resizing: bool, }, } impl Default for ClusterConfig { fn default() -> Self { // 24 depth slices, square clusters with at most 4096 total clusters // use max light distance as clusters max Z-depth, first slice extends to 5.0 Self::FixedZ { total: 4096, z_slices: 24, z_config: ClusterZConfig::default(), dynamic_resizing: true, } } } impl ClusterConfig { fn dimensions_for_screen_size(&self, screen_size: UVec2) -> UVec3 { match &self { ClusterConfig::None => UVec3::ZERO, ClusterConfig::Single => UVec3::ONE, ClusterConfig::XYZ { dimensions, .. } => *dimensions, ClusterConfig::FixedZ { total, z_slices, .. } => { let aspect_ratio = screen_size.x as f32 / screen_size.y as f32; let mut z_slices = *z_slices; if *total < z_slices { warn!("ClusterConfig has more z-slices than total clusters!"); z_slices = *total; } let per_layer = *total as f32 / z_slices as f32; let y = f32::sqrt(per_layer / aspect_ratio); let mut x = (y * aspect_ratio) as u32; let mut y = y as u32; // check extremes if x == 0 { x = 1; y = per_layer as u32; } if y == 0 { x = per_layer as u32; y = 1; } UVec3::new(x, y, z_slices) } } } fn first_slice_depth(&self) -> f32 { match self { ClusterConfig::None | ClusterConfig::Single => 0.0, ClusterConfig::XYZ { z_config, .. } | ClusterConfig::FixedZ { z_config, .. } => { z_config.first_slice_depth } } } fn far_z_mode(&self) -> ClusterFarZMode { match self { ClusterConfig::None => ClusterFarZMode::Constant(0.0), ClusterConfig::Single => ClusterFarZMode::MaxLightRange, ClusterConfig::XYZ { z_config, .. } | ClusterConfig::FixedZ { z_config, .. } => { z_config.far_z_mode } } } fn dynamic_resizing(&self) -> bool { match self { ClusterConfig::None | ClusterConfig::Single => false, ClusterConfig::XYZ { dynamic_resizing, .. } | ClusterConfig::FixedZ { dynamic_resizing, .. } => *dynamic_resizing, } } } #[derive(Component, Debug, Default)] pub struct Clusters { /// Tile size pub(crate) tile_size: UVec2, /// Number of clusters in x / y / z in the view frustum pub(crate) dimensions: UVec3, /// Distance to the far plane of the first depth slice. The first depth slice is special /// and explicitly-configured to avoid having unnecessarily many slices close to the camera. pub(crate) near: f32, pub(crate) far: f32, pub(crate) lights: Vec, } impl Clusters { fn update(&mut self, screen_size: UVec2, requested_dimensions: UVec3) { debug_assert!( requested_dimensions.x > 0 && requested_dimensions.y > 0 && requested_dimensions.z > 0 ); let tile_size = (screen_size.as_vec2() / requested_dimensions.xy().as_vec2()) .ceil() .as_uvec2() .max(UVec2::ONE); self.tile_size = tile_size; self.dimensions = (screen_size.as_vec2() / tile_size.as_vec2()) .ceil() .as_uvec2() .extend(requested_dimensions.z) .max(UVec3::ONE); // NOTE: Maximum 4096 clusters due to uniform buffer size constraints debug_assert!(self.dimensions.x * self.dimensions.y * self.dimensions.z <= 4096); } fn clear(&mut self) { self.tile_size = UVec2::ONE; self.dimensions = UVec3::ZERO; self.near = 0.0; self.far = 0.0; self.lights.clear(); } } fn clip_to_view(inverse_projection: Mat4, clip: Vec4) -> Vec4 { let view = inverse_projection * clip; view / view.w } pub fn add_clusters( mut commands: Commands, cameras: Query<(Entity, Option<&ClusterConfig>), (With, Without)>, ) { for (entity, config) in cameras.iter() { let config = config.copied().unwrap_or_default(); // actual settings here don't matter - they will be overwritten in assign_lights_to_clusters commands .entity(entity) .insert_bundle((Clusters::default(), config)); } } #[derive(Clone, Component, Debug, Default)] pub struct VisiblePointLights { pub(crate) entities: Vec, } impl VisiblePointLights { #[inline] pub fn iter(&self) -> impl DoubleEndedIterator { self.entities.iter() } #[inline] pub fn len(&self) -> usize { self.entities.len() } #[inline] pub fn is_empty(&self) -> bool { self.entities.is_empty() } } // NOTE: Keep in sync with bevy_pbr/src/render/pbr.wgsl fn view_z_to_z_slice( cluster_factors: Vec2, z_slices: u32, view_z: f32, is_orthographic: bool, ) -> u32 { let z_slice = if is_orthographic { // NOTE: view_z is correct in the orthographic case ((view_z - cluster_factors.x) * cluster_factors.y).floor() as u32 } else { // NOTE: had to use -view_z to make it positive else log(negative) is nan ((-view_z).ln() * cluster_factors.x - cluster_factors.y + 1.0) as u32 }; // NOTE: We use min as we may limit the far z plane used for clustering to be closeer than // the furthest thing being drawn. This means that we need to limit to the maximum cluster. z_slice.min(z_slices - 1) } // NOTE: Keep in sync as the inverse of view_z_to_z_slice above fn z_slice_to_view_z( near: f32, far: f32, z_slices: u32, z_slice: u32, is_orthographic: bool, ) -> f32 { if is_orthographic { return -near - (far - near) * z_slice as f32 / z_slices as f32; } // Perspective if z_slice == 0 { 0.0 } else { -near * (far / near).powf((z_slice - 1) as f32 / (z_slices - 1) as f32) } } fn ndc_position_to_cluster( cluster_dimensions: UVec3, cluster_factors: Vec2, is_orthographic: bool, ndc_p: Vec3, view_z: f32, ) -> UVec3 { let cluster_dimensions_f32 = cluster_dimensions.as_vec3(); let frag_coord = (ndc_p.xy() * VEC2_HALF_NEGATIVE_Y + VEC2_HALF).clamp(Vec2::ZERO, Vec2::ONE); let xy = (frag_coord * cluster_dimensions_f32.xy()).floor(); let z_slice = view_z_to_z_slice( cluster_factors, cluster_dimensions.z, view_z, is_orthographic, ); xy.as_uvec2() .extend(z_slice) .clamp(UVec3::ZERO, cluster_dimensions - UVec3::ONE) } const VEC2_HALF: Vec2 = Vec2::splat(0.5); const VEC2_HALF_NEGATIVE_Y: Vec2 = Vec2::new(0.5, -0.5); // Calculate bounds for the light using a view space aabb. // Returns a (Vec3, Vec3) containing min and max with // x and y in normalized device coordinates with range [-1, 1] // z in view space, with range [-inf, -f32::MIN_POSITIVE] fn cluster_space_light_aabb( inverse_view_transform: Mat4, projection_matrix: Mat4, light_sphere: &Sphere, ) -> (Vec3, Vec3) { let light_aabb_view = Aabb { center: Vec3A::from(inverse_view_transform * light_sphere.center.extend(1.0)), half_extents: Vec3A::splat(light_sphere.radius), }; let (mut light_aabb_view_min, mut light_aabb_view_max) = (light_aabb_view.min(), light_aabb_view.max()); // Constrain view z to be negative - i.e. in front of the camera // When view z is >= 0.0 and we're using a perspective projection, bad things happen. // At view z == 0.0, ndc x,y are mathematically undefined. At view z > 0.0, i.e. behind the camera, // the perspective projection flips the directions of the axes. This breaks assumptions about // use of min/max operations as something that was to the left in view space is now returning a // coordinate that for view z in front of the camera would be on the right, but at view z behind the // camera is on the left. So, we just constrain view z to be < 0.0 and necessarily in front of the camera. light_aabb_view_min.z = light_aabb_view_min.z.min(-f32::MIN_POSITIVE); light_aabb_view_max.z = light_aabb_view_max.z.min(-f32::MIN_POSITIVE); // Is there a cheaper way to do this? The problem is that because of perspective // the point at max z but min xy may be less xy in screenspace, and similar. As // such, projecting the min and max xy at both the closer and further z and taking // the min and max of those projected points addresses this. let ( light_aabb_view_xymin_near, light_aabb_view_xymin_far, light_aabb_view_xymax_near, light_aabb_view_xymax_far, ) = ( light_aabb_view_min, light_aabb_view_min.xy().extend(light_aabb_view_max.z), light_aabb_view_max.xy().extend(light_aabb_view_min.z), light_aabb_view_max, ); let ( light_aabb_clip_xymin_near, light_aabb_clip_xymin_far, light_aabb_clip_xymax_near, light_aabb_clip_xymax_far, ) = ( projection_matrix * light_aabb_view_xymin_near.extend(1.0), projection_matrix * light_aabb_view_xymin_far.extend(1.0), projection_matrix * light_aabb_view_xymax_near.extend(1.0), projection_matrix * light_aabb_view_xymax_far.extend(1.0), ); let ( light_aabb_ndc_xymin_near, light_aabb_ndc_xymin_far, light_aabb_ndc_xymax_near, light_aabb_ndc_xymax_far, ) = ( light_aabb_clip_xymin_near.xyz() / light_aabb_clip_xymin_near.w, light_aabb_clip_xymin_far.xyz() / light_aabb_clip_xymin_far.w, light_aabb_clip_xymax_near.xyz() / light_aabb_clip_xymax_near.w, light_aabb_clip_xymax_far.xyz() / light_aabb_clip_xymax_far.w, ); let (light_aabb_ndc_min, light_aabb_ndc_max) = ( light_aabb_ndc_xymin_near .min(light_aabb_ndc_xymin_far) .min(light_aabb_ndc_xymax_near) .min(light_aabb_ndc_xymax_far), light_aabb_ndc_xymin_near .max(light_aabb_ndc_xymin_far) .max(light_aabb_ndc_xymax_near) .max(light_aabb_ndc_xymax_far), ); // clamp to ndc coords without depth let (aabb_min_ndc, aabb_max_ndc) = ( light_aabb_ndc_min.xy().clamp(NDC_MIN, NDC_MAX), light_aabb_ndc_max.xy().clamp(NDC_MIN, NDC_MAX), ); // pack unadjusted z depth into the vecs ( aabb_min_ndc.extend(light_aabb_view_min.z), aabb_max_ndc.extend(light_aabb_view_max.z), ) } const NDC_MIN: Vec2 = Vec2::NEG_ONE; const NDC_MAX: Vec2 = Vec2::ONE; // Sort point lights with shadows enabled first, then by a stable key so that the index // can be used to limit the number of point light shadows to render based on the device and // we keep a stable set of lights visible pub(crate) fn point_light_order( (entity_1, shadows_enabled_1): (&Entity, &bool), (entity_2, shadows_enabled_2): (&Entity, &bool), ) -> std::cmp::Ordering { shadows_enabled_1 .cmp(shadows_enabled_2) .reverse() .then_with(|| entity_1.cmp(entity_2)) } #[derive(Clone, Copy)] // data required for assigning lights to clusters pub(crate) struct PointLightAssignmentData { entity: Entity, translation: Vec3, range: f32, shadows_enabled: bool, } #[derive(Default)] pub struct GlobalVisiblePointLights { entities: HashSet, } impl GlobalVisiblePointLights { #[inline] pub fn iter(&self) -> impl Iterator { self.entities.iter() } #[inline] pub fn contains(&self, entity: Entity) -> bool { self.entities.contains(&entity) } } // NOTE: Run this before update_point_light_frusta! #[allow(clippy::too_many_arguments)] pub(crate) fn assign_lights_to_clusters( mut commands: Commands, mut global_lights: ResMut, mut views: Query<( Entity, &GlobalTransform, &Camera, &Frustum, &ClusterConfig, &mut Clusters, Option<&mut VisiblePointLights>, )>, lights_query: Query<(Entity, &GlobalTransform, &PointLight, &Visibility)>, mut lights: Local>, mut max_point_lights_warning_emitted: Local, render_device: Option>, ) { let render_device = match render_device { Some(render_device) => render_device, None => return, }; global_lights.entities.clear(); lights.clear(); // collect just the relevant light query data into a persisted vec to avoid reallocating each frame lights.extend( lights_query .iter() .filter(|(.., visibility)| visibility.is_visible) .map( |(entity, transform, light, _visibility)| PointLightAssignmentData { entity, translation: transform.translation, shadows_enabled: light.shadows_enabled, range: light.range, }, ), ); let clustered_forward_buffer_binding_type = render_device.get_supported_read_only_binding_type(CLUSTERED_FORWARD_STORAGE_BUFFER_COUNT); let supports_storage_buffers = matches!( clustered_forward_buffer_binding_type, BufferBindingType::Storage { .. } ); if lights.len() > MAX_UNIFORM_BUFFER_POINT_LIGHTS && !supports_storage_buffers { lights.sort_by(|light_1, light_2| { point_light_order( (&light_1.entity, &light_1.shadows_enabled), (&light_2.entity, &light_2.shadows_enabled), ) }); // check each light against each view's frustum, keep only those that affect at least one of our views let frusta: Vec<_> = views .iter() .map(|(_, _, _, frustum, _, _, _)| *frustum) .collect(); let mut lights_in_view_count = 0; lights.retain(|light| { // take one extra light to check if we should emit the warning if lights_in_view_count == MAX_UNIFORM_BUFFER_POINT_LIGHTS + 1 { false } else { let light_sphere = Sphere { center: Vec3A::from(light.translation), radius: light.range, }; let light_in_view = frusta .iter() .any(|frustum| frustum.intersects_sphere(&light_sphere, true)); if light_in_view { lights_in_view_count += 1; } light_in_view } }); if lights.len() > MAX_UNIFORM_BUFFER_POINT_LIGHTS && !*max_point_lights_warning_emitted { warn!( "MAX_UNIFORM_BUFFER_POINT_LIGHTS ({}) exceeded", MAX_UNIFORM_BUFFER_POINT_LIGHTS ); *max_point_lights_warning_emitted = true; } lights.truncate(MAX_UNIFORM_BUFFER_POINT_LIGHTS); } for (view_entity, camera_transform, camera, frustum, config, clusters, mut visible_lights) in views.iter_mut() { let clusters = clusters.into_inner(); if matches!(config, ClusterConfig::None) { if visible_lights.is_some() { commands.entity(view_entity).remove::(); } clusters.clear(); continue; } let screen_size = if let Some(screen_size) = camera.physical_viewport_size() { screen_size } else { clusters.clear(); continue; }; let mut requested_cluster_dimensions = config.dimensions_for_screen_size(screen_size); let view_transform = camera_transform.compute_matrix(); let inverse_view_transform = view_transform.inverse(); let is_orthographic = camera.projection_matrix().w_axis.w == 1.0; let far_z = match config.far_z_mode() { ClusterFarZMode::MaxLightRange => { let inverse_view_row_2 = inverse_view_transform.row(2); lights .iter() .map(|light| { -inverse_view_row_2.dot(light.translation.extend(1.0)) + light.range }) .reduce(f32::max) .unwrap_or(0.0) } ClusterFarZMode::Constant(far) => far, }; let first_slice_depth = match (is_orthographic, requested_cluster_dimensions.z) { (true, _) => { // NOTE: Based on glam's Mat4::orthographic_rh(), as used to calculate the orthographic projection // matrix, we can calculate the projection's view-space near plane as follows: // component 3,2 = r * near and 2,2 = r where r = 1.0 / (near - far) // There is a caveat here that when calculating the projection matrix, near and far were swapped to give // reversed z, consistent with the perspective projection. So, // 3,2 = r * far and 2,2 = r where r = 1.0 / (far - near) // rearranging r = 1.0 / (far - near), r * (far - near) = 1.0, r * far - 1.0 = r * near, near = (r * far - 1.0) / r // = (3,2 - 1.0) / 2,2 (camera.projection_matrix().w_axis.z - 1.0) / camera.projection_matrix().z_axis.z } (false, 1) => config.first_slice_depth().max(far_z), _ => config.first_slice_depth(), }; // NOTE: Ensure the far_z is at least as far as the first_depth_slice to avoid clustering problems. let far_z = far_z.max(first_slice_depth); let cluster_factors = calculate_cluster_factors( first_slice_depth, far_z, requested_cluster_dimensions.z as f32, is_orthographic, ); if config.dynamic_resizing() { let mut cluster_index_estimate = 0.0; for light in lights.iter() { let light_sphere = Sphere { center: Vec3A::from(light.translation), radius: light.range, }; // Check if the light is within the view frustum if !frustum.intersects_sphere(&light_sphere, true) { continue; } // calculate a conservative aabb estimate of number of clusters affected by this light // this overestimates index counts by at most 50% (and typically much less) when the whole light range is in view // it can overestimate more significantly when light ranges are only partially in view let (light_aabb_min, light_aabb_max) = cluster_space_light_aabb( inverse_view_transform, camera.projection_matrix(), &light_sphere, ); // since we won't adjust z slices we can calculate exact number of slices required in z dimension let z_cluster_min = view_z_to_z_slice( cluster_factors, requested_cluster_dimensions.z, light_aabb_min.z, is_orthographic, ); let z_cluster_max = view_z_to_z_slice( cluster_factors, requested_cluster_dimensions.z, light_aabb_max.z, is_orthographic, ); let z_count = z_cluster_min.max(z_cluster_max) - z_cluster_min.min(z_cluster_max) + 1; // calculate x/y count using floats to avoid overestimating counts due to large initial tile sizes let xy_min = light_aabb_min.xy(); let xy_max = light_aabb_max.xy(); // multiply by 0.5 to move from [-1,1] to [-0.5, 0.5], max extent of 1 in each dimension let xy_count = (xy_max - xy_min) * 0.5 * Vec2::new( requested_cluster_dimensions.x as f32, requested_cluster_dimensions.y as f32, ); // add up to 2 to each axis to account for overlap let x_overlap = if xy_min.x <= -1.0 { 0.0 } else { 1.0 } + if xy_max.x >= 1.0 { 0.0 } else { 1.0 }; let y_overlap = if xy_min.y <= -1.0 { 0.0 } else { 1.0 } + if xy_max.y >= 1.0 { 0.0 } else { 1.0 }; cluster_index_estimate += (xy_count.x + x_overlap) * (xy_count.y + y_overlap) * z_count as f32; } if cluster_index_estimate > ViewClusterBindings::MAX_INDICES as f32 { // scale x and y cluster count to be able to fit all our indices // we take the ratio of the actual indices over the index estimate. // this not not guaranteed to be small enough due to overlapped tiles, but // the conservative estimate is more than sufficient to cover the // difference let index_ratio = ViewClusterBindings::MAX_INDICES as f32 / cluster_index_estimate as f32; let xy_ratio = index_ratio.sqrt(); requested_cluster_dimensions.x = ((requested_cluster_dimensions.x as f32 * xy_ratio).floor() as u32).max(1); requested_cluster_dimensions.y = ((requested_cluster_dimensions.y as f32 * xy_ratio).floor() as u32).max(1); } } clusters.update(screen_size, requested_cluster_dimensions); clusters.near = first_slice_depth; clusters.far = far_z; // NOTE: Maximum 4096 clusters due to uniform buffer size constraints debug_assert!( clusters.dimensions.x * clusters.dimensions.y * clusters.dimensions.z <= 4096 ); let inverse_projection = camera.projection_matrix().inverse(); for lights in &mut clusters.lights { lights.entities.clear(); } clusters.lights.resize_with( (clusters.dimensions.x * clusters.dimensions.y * clusters.dimensions.z) as usize, VisiblePointLights::default, ); // Calculate the x/y/z cluster frustum planes in view space let mut x_planes = Vec::with_capacity(clusters.dimensions.x as usize + 1); let mut y_planes = Vec::with_capacity(clusters.dimensions.y as usize + 1); let mut z_planes = Vec::with_capacity(clusters.dimensions.z as usize + 1); if is_orthographic { let x_slices = clusters.dimensions.x as f32; for x in 0..=clusters.dimensions.x { let x_proportion = x as f32 / x_slices; let x_pos = x_proportion * 2.0 - 1.0; let view_x = clip_to_view(inverse_projection, Vec4::new(x_pos, 0.0, 1.0, 1.0)).x; let normal = Vec3::X; let d = view_x * normal.x; x_planes.push(Plane::new(normal.extend(d))); } let y_slices = clusters.dimensions.y as f32; for y in 0..=clusters.dimensions.y { let y_proportion = 1.0 - y as f32 / y_slices; let y_pos = y_proportion * 2.0 - 1.0; let view_y = clip_to_view(inverse_projection, Vec4::new(0.0, y_pos, 1.0, 1.0)).y; let normal = Vec3::Y; let d = view_y * normal.y; y_planes.push(Plane::new(normal.extend(d))); } } else { let x_slices = clusters.dimensions.x as f32; for x in 0..=clusters.dimensions.x { let x_proportion = x as f32 / x_slices; let x_pos = x_proportion * 2.0 - 1.0; let nb = clip_to_view(inverse_projection, Vec4::new(x_pos, -1.0, 1.0, 1.0)).xyz(); let nt = clip_to_view(inverse_projection, Vec4::new(x_pos, 1.0, 1.0, 1.0)).xyz(); let normal = nb.cross(nt); let d = nb.dot(normal); x_planes.push(Plane::new(normal.extend(d))); } let y_slices = clusters.dimensions.y as f32; for y in 0..=clusters.dimensions.y { let y_proportion = 1.0 - y as f32 / y_slices; let y_pos = y_proportion * 2.0 - 1.0; let nl = clip_to_view(inverse_projection, Vec4::new(-1.0, y_pos, 1.0, 1.0)).xyz(); let nr = clip_to_view(inverse_projection, Vec4::new(1.0, y_pos, 1.0, 1.0)).xyz(); let normal = nr.cross(nl); let d = nr.dot(normal); y_planes.push(Plane::new(normal.extend(d))); } } let z_slices = clusters.dimensions.z; for z in 0..=z_slices { let view_z = z_slice_to_view_z(first_slice_depth, far_z, z_slices, z, is_orthographic); let normal = -Vec3::Z; let d = view_z * normal.z; z_planes.push(Plane::new(normal.extend(d))); } let mut update_from_light_intersections = |visible_lights: &mut Vec| { for light in lights.iter() { let light_sphere = Sphere { center: Vec3A::from(light.translation), radius: light.range, }; // Check if the light is within the view frustum if !frustum.intersects_sphere(&light_sphere, true) { continue; } // NOTE: The light intersects the frustum so it must be visible and part of the global set global_lights.entities.insert(light.entity); visible_lights.push(light.entity); // note: caching seems to be slower than calling twice for this aabb calculation let (light_aabb_xy_ndc_z_view_min, light_aabb_xy_ndc_z_view_max) = cluster_space_light_aabb( inverse_view_transform, camera.projection_matrix(), &light_sphere, ); let min_cluster = ndc_position_to_cluster( clusters.dimensions, cluster_factors, is_orthographic, light_aabb_xy_ndc_z_view_min, light_aabb_xy_ndc_z_view_min.z, ); let max_cluster = ndc_position_to_cluster( clusters.dimensions, cluster_factors, is_orthographic, light_aabb_xy_ndc_z_view_max, light_aabb_xy_ndc_z_view_max.z, ); let (min_cluster, max_cluster) = (min_cluster.min(max_cluster), min_cluster.max(max_cluster)); // What follows is the Iterative Sphere Refinement algorithm from Just Cause 3 // Persson et al, Practical Clustered Shading // http://newq.net/dl/pub/s2015_practical.pdf // NOTE: A sphere under perspective projection is no longer a sphere. It gets // stretched and warped, which prevents simpler algorithms from being correct // as they often assume that the widest part of the sphere under projection is the // center point on the axis of interest plus the radius, and that is not true! let view_light_sphere = Sphere { center: Vec3A::from(inverse_view_transform * light_sphere.center.extend(1.0)), radius: light_sphere.radius, }; let light_center_clip = camera.projection_matrix() * view_light_sphere.center.extend(1.0); let light_center_ndc = light_center_clip.xyz() / light_center_clip.w; let cluster_coordinates = ndc_position_to_cluster( clusters.dimensions, cluster_factors, is_orthographic, light_center_ndc, view_light_sphere.center.z, ); let z_center = if light_center_ndc.z <= 1.0 { Some(cluster_coordinates.z) } else { None }; let y_center = if light_center_ndc.y > 1.0 { None } else if light_center_ndc.y < -1.0 { Some(clusters.dimensions.y + 1) } else { Some(cluster_coordinates.y) }; for z in min_cluster.z..=max_cluster.z { let mut z_light = view_light_sphere.clone(); if z_center.is_none() || z != z_center.unwrap() { // The z plane closer to the light has the larger radius circle where the // light sphere intersects the z plane. let z_plane = if z_center.is_some() && z < z_center.unwrap() { z_planes[(z + 1) as usize] } else { z_planes[z as usize] }; // Project the sphere to this z plane and use its radius as the radius of a // new, refined sphere. if let Some(projected) = project_to_plane_z(z_light, z_plane) { z_light = projected; } else { continue; } } for y in min_cluster.y..=max_cluster.y { let mut y_light = z_light.clone(); if y_center.is_none() || y != y_center.unwrap() { // The y plane closer to the light has the larger radius circle where the // light sphere intersects the y plane. let y_plane = if y_center.is_some() && y < y_center.unwrap() { y_planes[(y + 1) as usize] } else { y_planes[y as usize] }; // Project the refined sphere to this y plane and use its radius as the // radius of a new, even more refined sphere. if let Some(projected) = project_to_plane_y(y_light, y_plane, is_orthographic) { y_light = projected; } else { continue; } } // Loop from the left to find the first affected cluster let mut min_x = min_cluster.x; loop { if min_x >= max_cluster.x || -get_distance_x( x_planes[(min_x + 1) as usize], y_light.center, is_orthographic, ) + y_light.radius > 0.0 { break; } min_x += 1; } // Loop from the right to find the last affected cluster let mut max_x = max_cluster.x; loop { if max_x <= min_x || get_distance_x( x_planes[max_x as usize], y_light.center, is_orthographic, ) + y_light.radius > 0.0 { break; } max_x -= 1; } let mut cluster_index = ((y * clusters.dimensions.x + min_x) * clusters.dimensions.z + z) as usize; // Mark the clusters in the range as affected for _ in min_x..=max_x { clusters.lights[cluster_index].entities.push(light.entity); cluster_index += clusters.dimensions.z as usize; } } } } }; // reuse existing visible lights Vec, if it exists if let Some(visible_lights) = visible_lights.as_mut() { visible_lights.entities.clear(); update_from_light_intersections(&mut visible_lights.entities); } else { let mut entities = Vec::new(); update_from_light_intersections(&mut entities); commands .entity(view_entity) .insert(VisiblePointLights { entities }); } } } // NOTE: This exploits the fact that a x-plane normal has only x and z components fn get_distance_x(plane: Plane, point: Vec3A, is_orthographic: bool) -> f32 { if is_orthographic { point.x - plane.d() } else { // Distance from a point to a plane: // signed distance to plane = (nx * px + ny * py + nz * pz + d) / n.length() // NOTE: For a x-plane, ny and d are 0 and we have a unit normal // = nx * px + nz * pz plane.normal_d().xz().dot(point.xz()) } } // NOTE: This exploits the fact that a z-plane normal has only a z component fn project_to_plane_z(z_light: Sphere, z_plane: Plane) -> Option { // p = sphere center // n = plane normal // d = n.p if p is in the plane // NOTE: For a z-plane, nx and ny are both 0 // d = px * nx + py * ny + pz * nz // = pz * nz // => pz = d / nz let z = z_plane.d() / z_plane.normal_d().z; let distance_to_plane = z - z_light.center.z; if distance_to_plane.abs() > z_light.radius { return None; } Some(Sphere { center: Vec3A::from(z_light.center.xy().extend(z)), // hypotenuse length = radius // pythagorus = (distance to plane)^2 + b^2 = radius^2 radius: (z_light.radius * z_light.radius - distance_to_plane * distance_to_plane).sqrt(), }) } // NOTE: This exploits the fact that a y-plane normal has only y and z components fn project_to_plane_y(y_light: Sphere, y_plane: Plane, is_orthographic: bool) -> Option { let distance_to_plane = if is_orthographic { y_plane.d() - y_light.center.y } else { -y_light.center.yz().dot(y_plane.normal_d().yz()) }; if distance_to_plane.abs() > y_light.radius { return None; } Some(Sphere { center: y_light.center + distance_to_plane * y_plane.normal(), radius: (y_light.radius * y_light.radius - distance_to_plane * distance_to_plane).sqrt(), }) } pub fn update_directional_light_frusta( mut views: Query< ( &GlobalTransform, &DirectionalLight, &mut Frustum, &Visibility, ), Or<(Changed, Changed)>, >, ) { for (transform, directional_light, mut frustum, visibility) in views.iter_mut() { // The frustum is used for culling meshes to the light for shadow mapping // so if shadow mapping is disabled for this light, then the frustum is // not needed. if !directional_light.shadows_enabled || !visibility.is_visible { continue; } let view_projection = directional_light.shadow_projection.get_projection_matrix() * transform.compute_matrix().inverse(); *frustum = Frustum::from_view_projection( &view_projection, &transform.translation, &transform.back(), directional_light.shadow_projection.far(), ); } } // NOTE: Run this after assign_lights_to_clusters! pub fn update_point_light_frusta( global_lights: Res, mut views: Query< (Entity, &GlobalTransform, &PointLight, &mut CubemapFrusta), Or<(Changed, Changed)>, >, ) { let projection = Mat4::perspective_infinite_reverse_rh(std::f32::consts::FRAC_PI_2, 1.0, POINT_LIGHT_NEAR_Z); let view_rotations = CUBE_MAP_FACES .iter() .map(|CubeMapFace { target, up }| GlobalTransform::identity().looking_at(*target, *up)) .collect::>(); for (entity, transform, point_light, mut cubemap_frusta) in views.iter_mut() { // The frusta are used for culling meshes to the light for shadow mapping // so if shadow mapping is disabled for this light, then the frusta are // not needed. // Also, if the light is not relevant for any cluster, it will not be in the // global lights set and so there is no need to update its frusta. if !point_light.shadows_enabled || !global_lights.entities.contains(&entity) { continue; } // ignore scale because we don't want to effectively scale light radius and range // by applying those as a view transform to shadow map rendering of objects // and ignore rotation because we want the shadow map projections to align with the axes let view_translation = GlobalTransform::from_translation(transform.translation); let view_backward = transform.back(); for (view_rotation, frustum) in view_rotations.iter().zip(cubemap_frusta.iter_mut()) { let view = view_translation * *view_rotation; let view_projection = projection * view.compute_matrix().inverse(); *frustum = Frustum::from_view_projection( &view_projection, &transform.translation, &view_backward, point_light.range, ); } } } pub fn check_light_mesh_visibility( visible_point_lights: Query<&VisiblePointLights>, mut point_lights: Query<( &PointLight, &GlobalTransform, &CubemapFrusta, &mut CubemapVisibleEntities, Option<&RenderLayers>, )>, mut directional_lights: Query<( &DirectionalLight, &Frustum, &mut VisibleEntities, Option<&RenderLayers>, &Visibility, )>, mut visible_entity_query: Query< ( Entity, &Visibility, &mut ComputedVisibility, Option<&RenderLayers>, Option<&Aabb>, Option<&GlobalTransform>, ), Without, >, ) { // Directonal lights for (directional_light, frustum, mut visible_entities, maybe_view_mask, visibility) in directional_lights.iter_mut() { visible_entities.entities.clear(); // NOTE: If shadow mapping is disabled for the light then it must have no visible entities if !directional_light.shadows_enabled || !visibility.is_visible { continue; } let view_mask = maybe_view_mask.copied().unwrap_or_default(); for ( entity, visibility, mut computed_visibility, maybe_entity_mask, maybe_aabb, maybe_transform, ) in visible_entity_query.iter_mut() { if !visibility.is_visible { continue; } let entity_mask = maybe_entity_mask.copied().unwrap_or_default(); if !view_mask.intersects(&entity_mask) { continue; } // If we have an aabb and transform, do frustum culling if let (Some(aabb), Some(transform)) = (maybe_aabb, maybe_transform) { if !frustum.intersects_obb(aabb, &transform.compute_matrix(), true) { continue; } } computed_visibility.is_visible = true; visible_entities.entities.push(entity); } // TODO: check for big changes in visible entities len() vs capacity() (ex: 2x) and resize // to prevent holding unneeded memory } // Point lights for visible_lights in visible_point_lights.iter() { for light_entity in visible_lights.entities.iter().copied() { if let Ok(( point_light, transform, cubemap_frusta, mut cubemap_visible_entities, maybe_view_mask, )) = point_lights.get_mut(light_entity) { for visible_entities in cubemap_visible_entities.iter_mut() { visible_entities.entities.clear(); } // NOTE: If shadow mapping is disabled for the light then it must have no visible entities if !point_light.shadows_enabled { continue; } let view_mask = maybe_view_mask.copied().unwrap_or_default(); let light_sphere = Sphere { center: Vec3A::from(transform.translation), radius: point_light.range, }; for ( entity, visibility, mut computed_visibility, maybe_entity_mask, maybe_aabb, maybe_transform, ) in visible_entity_query.iter_mut() { if !visibility.is_visible { continue; } let entity_mask = maybe_entity_mask.copied().unwrap_or_default(); if !view_mask.intersects(&entity_mask) { continue; } // If we have an aabb and transform, do frustum culling if let (Some(aabb), Some(transform)) = (maybe_aabb, maybe_transform) { let model_to_world = transform.compute_matrix(); // Do a cheap sphere vs obb test to prune out most meshes outside the sphere of the light if !light_sphere.intersects_obb(aabb, &model_to_world) { continue; } for (frustum, visible_entities) in cubemap_frusta .iter() .zip(cubemap_visible_entities.iter_mut()) { if frustum.intersects_obb(aabb, &model_to_world, true) { computed_visibility.is_visible = true; visible_entities.entities.push(entity); } } } else { computed_visibility.is_visible = true; for visible_entities in cubemap_visible_entities.iter_mut() { visible_entities.entities.push(entity); } } } // TODO: check for big changes in visible entities len() vs capacity() (ex: 2x) and resize // to prevent holding unneeded memory } } } } #[cfg(test)] mod test { use super::*; fn test_cluster_tiling(config: ClusterConfig, screen_size: UVec2) -> Clusters { let dims = config.dimensions_for_screen_size(screen_size); // note: near & far do not affect tiling let mut clusters = Clusters::default(); clusters.update(screen_size, dims); // check we cover the screen assert!(clusters.tile_size.x * clusters.dimensions.x >= screen_size.x); assert!(clusters.tile_size.y * clusters.dimensions.y >= screen_size.y); // check a smaller number of clusters would not cover the screen assert!(clusters.tile_size.x * (clusters.dimensions.x - 1) < screen_size.x); assert!(clusters.tile_size.y * (clusters.dimensions.y - 1) < screen_size.y); // check a smaller tilesize would not cover the screen assert!((clusters.tile_size.x - 1) * clusters.dimensions.x < screen_size.x); assert!((clusters.tile_size.y - 1) * clusters.dimensions.y < screen_size.y); // check we don't have more clusters than pixels assert!(clusters.dimensions.x <= screen_size.x); assert!(clusters.dimensions.y <= screen_size.y); clusters } #[test] // check tiling for small screen sizes fn test_default_cluster_setup_small_screensizes() { for x in 1..100 { for y in 1..100 { let screen_size = UVec2::new(x, y); let clusters = test_cluster_tiling(ClusterConfig::default(), screen_size); assert!( clusters.dimensions.x * clusters.dimensions.y * clusters.dimensions.z <= 4096 ); } } } #[test] // check tiling for long thin screen sizes fn test_default_cluster_setup_small_x() { for x in 1..10 { for y in 1..5000 { let screen_size = UVec2::new(x, y); let clusters = test_cluster_tiling(ClusterConfig::default(), screen_size); assert!( clusters.dimensions.x * clusters.dimensions.y * clusters.dimensions.z <= 4096 ); let screen_size = UVec2::new(y, x); let clusters = test_cluster_tiling(ClusterConfig::default(), screen_size); assert!( clusters.dimensions.x * clusters.dimensions.y * clusters.dimensions.z <= 4096 ); } } } }