diff --git a/crates/bevy_pbr/src/lib.rs b/crates/bevy_pbr/src/lib.rs index 3f40f9b826..c0b5668e1a 100644 --- a/crates/bevy_pbr/src/lib.rs +++ b/crates/bevy_pbr/src/lib.rs @@ -54,6 +54,14 @@ pub const PBR_TYPES_SHADER_HANDLE: HandleUntyped = HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 1708015359337029744); pub const PBR_BINDINGS_SHADER_HANDLE: HandleUntyped = HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 5635987986427308186); +pub const UTILS_HANDLE: HandleUntyped = + HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 1900548483293416725); +pub const CLUSTERED_FORWARD_HANDLE: HandleUntyped = + HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 166852093121196815); +pub const PBR_LIGHTING_HANDLE: HandleUntyped = + HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 14170772752254856967); +pub const SHADOWS_HANDLE: HandleUntyped = + HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 11350275143789590502); pub const PBR_SHADER_HANDLE: HandleUntyped = HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 4805239651767701046); pub const SHADOW_SHADER_HANDLE: HandleUntyped = @@ -77,6 +85,25 @@ impl Plugin for PbrPlugin { "render/pbr_bindings.wgsl", Shader::from_wgsl ); + load_internal_asset!(app, UTILS_HANDLE, "render/utils.wgsl", Shader::from_wgsl); + load_internal_asset!( + app, + CLUSTERED_FORWARD_HANDLE, + "render/clustered_forward.wgsl", + Shader::from_wgsl + ); + load_internal_asset!( + app, + PBR_LIGHTING_HANDLE, + "render/pbr_lighting.wgsl", + Shader::from_wgsl + ); + load_internal_asset!( + app, + SHADOWS_HANDLE, + "render/shadows.wgsl", + Shader::from_wgsl + ); load_internal_asset!(app, PBR_SHADER_HANDLE, "render/pbr.wgsl", Shader::from_wgsl); load_internal_asset!( app, diff --git a/crates/bevy_pbr/src/render/clustered_forward.wgsl b/crates/bevy_pbr/src/render/clustered_forward.wgsl new file mode 100644 index 0000000000..a27e4b33b6 --- /dev/null +++ b/crates/bevy_pbr/src/render/clustered_forward.wgsl @@ -0,0 +1,100 @@ +#define_import_path bevy_pbr::clustered_forward + +// NOTE: Keep in sync with bevy_pbr/src/light.rs +fn view_z_to_z_slice(view_z: f32, is_orthographic: bool) -> u32 { + var z_slice: u32 = 0u; + if (is_orthographic) { + // NOTE: view_z is correct in the orthographic case + z_slice = u32(floor((view_z - lights.cluster_factors.z) * lights.cluster_factors.w)); + } else { + // NOTE: had to use -view_z to make it positive else log(negative) is nan + z_slice = u32(log(-view_z) * lights.cluster_factors.z - lights.cluster_factors.w + 1.0); + } + // 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. + return min(z_slice, lights.cluster_dimensions.z - 1u); +} + +fn fragment_cluster_index(frag_coord: vec2, view_z: f32, is_orthographic: bool) -> u32 { + let xy = vec2(floor(frag_coord * lights.cluster_factors.xy)); + let z_slice = view_z_to_z_slice(view_z, is_orthographic); + // NOTE: Restricting cluster index to avoid undefined behavior when accessing uniform buffer + // arrays based on the cluster index. + return min( + (xy.y * lights.cluster_dimensions.x + xy.x) * lights.cluster_dimensions.z + z_slice, + lights.cluster_dimensions.w - 1u + ); +} + +// this must match CLUSTER_COUNT_SIZE in light.rs +let CLUSTER_COUNT_SIZE = 13u; +fn unpack_offset_and_count(cluster_index: u32) -> vec2 { +#ifdef NO_STORAGE_BUFFERS_SUPPORT + let offset_and_count = cluster_offsets_and_counts.data[cluster_index >> 2u][cluster_index & ((1u << 2u) - 1u)]; + return vec2( + // The offset is stored in the upper 32 - CLUSTER_COUNT_SIZE = 19 bits + (offset_and_count >> CLUSTER_COUNT_SIZE) & ((1u << 32u - CLUSTER_COUNT_SIZE) - 1u), + // The count is stored in the lower CLUSTER_COUNT_SIZE = 13 bits + offset_and_count & ((1u << CLUSTER_COUNT_SIZE) - 1u) + ); +#else + return cluster_offsets_and_counts.data[cluster_index]; +#endif +} + +fn get_light_id(index: u32) -> u32 { +#ifdef NO_STORAGE_BUFFERS_SUPPORT + // The index is correct but in cluster_light_index_lists we pack 4 u8s into a u32 + // This means the index into cluster_light_index_lists is index / 4 + let indices = cluster_light_index_lists.data[index >> 4u][(index >> 2u) & ((1u << 2u) - 1u)]; + // And index % 4 gives the sub-index of the u8 within the u32 so we shift by 8 * sub-index + return (indices >> (8u * (index & ((1u << 2u) - 1u)))) & ((1u << 8u) - 1u); +#else + return cluster_light_index_lists.data[index]; +#endif +} + +fn cluster_debug_visualization( + output_color: vec4, + view_z: f32, + is_orthographic: bool, + offset_and_count: vec2, + cluster_index: u32, +) -> vec4 { + // Cluster allocation debug (using 'over' alpha blending) +#ifdef CLUSTERED_FORWARD_DEBUG_Z_SLICES + // NOTE: This debug mode visualises the z-slices + let cluster_overlay_alpha = 0.1; + var z_slice: u32 = view_z_to_z_slice(view_z, is_orthographic); + // A hack to make the colors alternate a bit more + if ((z_slice & 1u) == 1u) { + z_slice = z_slice + lights.cluster_dimensions.z / 2u; + } + let slice_color = hsv2rgb(f32(z_slice) / f32(lights.cluster_dimensions.z + 1u), 1.0, 0.5); + output_color = vec4( + (1.0 - cluster_overlay_alpha) * output_color.rgb + cluster_overlay_alpha * slice_color, + output_color.a + ); +#endif // CLUSTERED_FORWARD_DEBUG_Z_SLICES +#ifdef CLUSTERED_FORWARD_DEBUG_CLUSTER_LIGHT_COMPLEXITY + // NOTE: This debug mode visualises the number of lights within the cluster that contains + // the fragment. It shows a sort of lighting complexity measure. + let cluster_overlay_alpha = 0.1; + let max_light_complexity_per_cluster = 64.0; + output_color.r = (1.0 - cluster_overlay_alpha) * output_color.r + + cluster_overlay_alpha * smoothStep(0.0, max_light_complexity_per_cluster, f32(offset_and_count[1])); + output_color.g = (1.0 - cluster_overlay_alpha) * output_color.g + + cluster_overlay_alpha * (1.0 - smoothStep(0.0, max_light_complexity_per_cluster, f32(offset_and_count[1]))); +#endif // CLUSTERED_FORWARD_DEBUG_CLUSTER_LIGHT_COMPLEXITY +#ifdef CLUSTERED_FORWARD_DEBUG_CLUSTER_COHERENCY + // NOTE: Visualizes the cluster to which the fragment belongs + let cluster_overlay_alpha = 0.1; + let cluster_color = hsv2rgb(random1D(f32(cluster_index)), 1.0, 0.5); + output_color = vec4( + (1.0 - cluster_overlay_alpha) * output_color.rgb + cluster_overlay_alpha * cluster_color, + output_color.a + ); +#endif // CLUSTERED_FORWARD_DEBUG_CLUSTER_COHERENCY + + return output_color; +} diff --git a/crates/bevy_pbr/src/render/pbr.wgsl b/crates/bevy_pbr/src/render/pbr.wgsl index 403f91abe8..7c7c282326 100644 --- a/crates/bevy_pbr/src/render/pbr.wgsl +++ b/crates/bevy_pbr/src/render/pbr.wgsl @@ -1,412 +1,11 @@ -// From the Filament design doc -// https://google.github.io/filament/Filament.html#table_symbols -// Symbol Definition -// v View unit vector -// l Incident light unit vector -// n Surface normal unit vector -// h Half unit vector between l and v -// f BRDF -// f_d Diffuse component of a BRDF -// f_r Specular component of a BRDF -// α Roughness, remapped from using input perceptualRoughness -// σ Diffuse reflectance -// Ω Spherical domain -// f0 Reflectance at normal incidence -// f90 Reflectance at grazing angle -// χ+(a) Heaviside function (1 if a>0 and 0 otherwise) -// nior Index of refraction (IOR) of an interface -// ⟨n⋅l⟩ Dot product clamped to [0..1] -// ⟨a⟩ Saturated value (clamped to [0..1]) - -// The Bidirectional Reflectance Distribution Function (BRDF) describes the surface response of a standard material -// and consists of two components, the diffuse component (f_d) and the specular component (f_r): -// f(v,l) = f_d(v,l) + f_r(v,l) -// -// The form of the microfacet model is the same for diffuse and specular -// f_r(v,l) = f_d(v,l) = 1 / { |n⋅v||n⋅l| } ∫_Ω D(m,α) G(v,l,m) f_m(v,l,m) (v⋅m) (l⋅m) dm -// -// In which: -// D, also called the Normal Distribution Function (NDF) models the distribution of the microfacets -// G models the visibility (or occlusion or shadow-masking) of the microfacets -// f_m is the microfacet BRDF and differs between specular and diffuse components -// -// The above integration needs to be approximated. - #import bevy_pbr::mesh_view_bindings #import bevy_pbr::pbr_bindings #import bevy_pbr::mesh_bindings -let PI: f32 = 3.141592653589793; - -fn saturate(value: f32) -> f32 { - return clamp(value, 0.0, 1.0); -} - -// distanceAttenuation is simply the square falloff of light intensity -// combined with a smooth attenuation at the edge of the light radius -// -// light radius is a non-physical construct for efficiency purposes, -// because otherwise every light affects every fragment in the scene -fn getDistanceAttenuation(distanceSquare: f32, inverseRangeSquared: f32) -> f32 { - let factor = distanceSquare * inverseRangeSquared; - let smoothFactor = saturate(1.0 - factor * factor); - let attenuation = smoothFactor * smoothFactor; - return attenuation * 1.0 / max(distanceSquare, 0.0001); -} - -// Normal distribution function (specular D) -// Based on https://google.github.io/filament/Filament.html#citation-walter07 - -// D_GGX(h,α) = α^2 / { π ((n⋅h)^2 (α2−1) + 1)^2 } - -// Simple implementation, has precision problems when using fp16 instead of fp32 -// see https://google.github.io/filament/Filament.html#listing_speculardfp16 -fn D_GGX(roughness: f32, NoH: f32, h: vec3) -> f32 { - let oneMinusNoHSquared = 1.0 - NoH * NoH; - let a = NoH * roughness; - let k = roughness / (oneMinusNoHSquared + a * a); - let d = k * k * (1.0 / PI); - return d; -} - -// Visibility function (Specular G) -// V(v,l,a) = G(v,l,α) / { 4 (n⋅v) (n⋅l) } -// such that f_r becomes -// f_r(v,l) = D(h,α) V(v,l,α) F(v,h,f0) -// where -// V(v,l,α) = 0.5 / { n⋅l sqrt((n⋅v)^2 (1−α2) + α2) + n⋅v sqrt((n⋅l)^2 (1−α2) + α2) } -// Note the two sqrt's, that may be slow on mobile, see https://google.github.io/filament/Filament.html#listing_approximatedspecularv -fn V_SmithGGXCorrelated(roughness: f32, NoV: f32, NoL: f32) -> f32 { - let a2 = roughness * roughness; - let lambdaV = NoL * sqrt((NoV - a2 * NoV) * NoV + a2); - let lambdaL = NoV * sqrt((NoL - a2 * NoL) * NoL + a2); - let v = 0.5 / (lambdaV + lambdaL); - return v; -} - -// Fresnel function -// see https://google.github.io/filament/Filament.html#citation-schlick94 -// F_Schlick(v,h,f_0,f_90) = f_0 + (f_90 − f_0) (1 − v⋅h)^5 -fn F_Schlick_vec(f0: vec3, f90: f32, VoH: f32) -> vec3 { - // not using mix to keep the vec3 and float versions identical - return f0 + (f90 - f0) * pow(1.0 - VoH, 5.0); -} - -fn F_Schlick(f0: f32, f90: f32, VoH: f32) -> f32 { - // not using mix to keep the vec3 and float versions identical - return f0 + (f90 - f0) * pow(1.0 - VoH, 5.0); -} - -fn fresnel(f0: vec3, LoH: f32) -> vec3 { - // f_90 suitable for ambient occlusion - // see https://google.github.io/filament/Filament.html#lighting/occlusion - let f90 = saturate(dot(f0, vec3(50.0 * 0.33))); - return F_Schlick_vec(f0, f90, LoH); -} - -// Specular BRDF -// https://google.github.io/filament/Filament.html#materialsystem/specularbrdf - -// Cook-Torrance approximation of the microfacet model integration using Fresnel law F to model f_m -// f_r(v,l) = { D(h,α) G(v,l,α) F(v,h,f0) } / { 4 (n⋅v) (n⋅l) } -fn specular(f0: vec3, roughness: f32, h: vec3, NoV: f32, NoL: f32, - NoH: f32, LoH: f32, specularIntensity: f32) -> vec3 { - let D = D_GGX(roughness, NoH, h); - let V = V_SmithGGXCorrelated(roughness, NoV, NoL); - let F = fresnel(f0, LoH); - - return (specularIntensity * D * V) * F; -} - -// Diffuse BRDF -// https://google.github.io/filament/Filament.html#materialsystem/diffusebrdf -// fd(v,l) = σ/π * 1 / { |n⋅v||n⋅l| } ∫Ω D(m,α) G(v,l,m) (v⋅m) (l⋅m) dm -// -// simplest approximation -// float Fd_Lambert() { -// return 1.0 / PI; -// } -// -// vec3 Fd = diffuseColor * Fd_Lambert(); -// -// Disney approximation -// See https://google.github.io/filament/Filament.html#citation-burley12 -// minimal quality difference -fn Fd_Burley(roughness: f32, NoV: f32, NoL: f32, LoH: f32) -> f32 { - let f90 = 0.5 + 2.0 * roughness * LoH * LoH; - let lightScatter = F_Schlick(1.0, f90, NoL); - let viewScatter = F_Schlick(1.0, f90, NoV); - return lightScatter * viewScatter * (1.0 / PI); -} - -// From https://www.unrealengine.com/en-US/blog/physically-based-shading-on-mobile -fn EnvBRDFApprox(f0: vec3, perceptual_roughness: f32, NoV: f32) -> vec3 { - let c0 = vec4(-1.0, -0.0275, -0.572, 0.022); - let c1 = vec4(1.0, 0.0425, 1.04, -0.04); - let r = perceptual_roughness * c0 + c1; - let a004 = min(r.x * r.x, exp2(-9.28 * NoV)) * r.x + r.y; - let AB = vec2(-1.04, 1.04) * a004 + r.zw; - return f0 * AB.x + AB.y; -} - -fn perceptualRoughnessToRoughness(perceptualRoughness: f32) -> f32 { - // clamp perceptual roughness to prevent precision problems - // According to Filament design 0.089 is recommended for mobile - // Filament uses 0.045 for non-mobile - let clampedPerceptualRoughness = clamp(perceptualRoughness, 0.089, 1.0); - return clampedPerceptualRoughness * clampedPerceptualRoughness; -} - -// from https://64.github.io/tonemapping/ -// reinhard on RGB oversaturates colors -fn reinhard(color: vec3) -> vec3 { - return color / (1.0 + color); -} - -fn reinhard_extended(color: vec3, max_white: f32) -> vec3 { - let numerator = color * (1.0 + (color / vec3(max_white * max_white))); - return numerator / (1.0 + color); -} - -// luminance coefficients from Rec. 709. -// https://en.wikipedia.org/wiki/Rec._709 -fn luminance(v: vec3) -> f32 { - return dot(v, vec3(0.2126, 0.7152, 0.0722)); -} - -fn change_luminance(c_in: vec3, l_out: f32) -> vec3 { - let l_in = luminance(c_in); - return c_in * (l_out / l_in); -} - -fn reinhard_luminance(color: vec3) -> vec3 { - let l_old = luminance(color); - let l_new = l_old / (1.0 + l_old); - return change_luminance(color, l_new); -} - -fn reinhard_extended_luminance(color: vec3, max_white_l: f32) -> vec3 { - let l_old = luminance(color); - let numerator = l_old * (1.0 + (l_old / (max_white_l * max_white_l))); - let l_new = numerator / (1.0 + l_old); - return change_luminance(color, l_new); -} - -// NOTE: Keep in sync with bevy_pbr/src/light.rs -fn view_z_to_z_slice(view_z: f32, is_orthographic: bool) -> u32 { - var z_slice: u32 = 0u; - if (is_orthographic) { - // NOTE: view_z is correct in the orthographic case - z_slice = u32(floor((view_z - lights.cluster_factors.z) * lights.cluster_factors.w)); - } else { - // NOTE: had to use -view_z to make it positive else log(negative) is nan - z_slice = u32(log(-view_z) * lights.cluster_factors.z - lights.cluster_factors.w + 1.0); - } - // 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. - return min(z_slice, lights.cluster_dimensions.z - 1u); -} - -fn fragment_cluster_index(frag_coord: vec2, view_z: f32, is_orthographic: bool) -> u32 { - let xy = vec2(floor(frag_coord * lights.cluster_factors.xy)); - let z_slice = view_z_to_z_slice(view_z, is_orthographic); - // NOTE: Restricting cluster index to avoid undefined behavior when accessing uniform buffer - // arrays based on the cluster index. - return min( - (xy.y * lights.cluster_dimensions.x + xy.x) * lights.cluster_dimensions.z + z_slice, - lights.cluster_dimensions.w - 1u - ); -} - -// this must match CLUSTER_COUNT_SIZE in light.rs -let CLUSTER_COUNT_SIZE = 13u; -fn unpack_offset_and_count(cluster_index: u32) -> vec2 { -#ifdef NO_STORAGE_BUFFERS_SUPPORT - let offset_and_count = cluster_offsets_and_counts.data[cluster_index >> 2u][cluster_index & ((1u << 2u) - 1u)]; - return vec2( - // The offset is stored in the upper 32 - CLUSTER_COUNT_SIZE = 19 bits - (offset_and_count >> CLUSTER_COUNT_SIZE) & ((1u << 32u - CLUSTER_COUNT_SIZE) - 1u), - // The count is stored in the lower CLUSTER_COUNT_SIZE = 13 bits - offset_and_count & ((1u << CLUSTER_COUNT_SIZE) - 1u) - ); -#else - return cluster_offsets_and_counts.data[cluster_index]; -#endif -} - -fn get_light_id(index: u32) -> u32 { -#ifdef NO_STORAGE_BUFFERS_SUPPORT - // The index is correct but in cluster_light_index_lists we pack 4 u8s into a u32 - // This means the index into cluster_light_index_lists is index / 4 - let indices = cluster_light_index_lists.data[index >> 4u][(index >> 2u) & ((1u << 2u) - 1u)]; - // And index % 4 gives the sub-index of the u8 within the u32 so we shift by 8 * sub-index - return (indices >> (8u * (index & ((1u << 2u) - 1u)))) & ((1u << 8u) - 1u); -#else - return cluster_light_index_lists.data[index]; -#endif -} - -fn point_light( - world_position: vec3, light: PointLight, roughness: f32, NdotV: f32, N: vec3, V: vec3, - R: vec3, F0: vec3, diffuseColor: vec3 -) -> vec3 { - let light_to_frag = light.position_radius.xyz - world_position.xyz; - let distance_square = dot(light_to_frag, light_to_frag); - let rangeAttenuation = - getDistanceAttenuation(distance_square, light.color_inverse_square_range.w); - - // Specular. - // Representative Point Area Lights. - // see http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf p14-16 - let a = roughness; - let centerToRay = dot(light_to_frag, R) * R - light_to_frag; - let closestPoint = light_to_frag + centerToRay * saturate(light.position_radius.w * inverseSqrt(dot(centerToRay, centerToRay))); - let LspecLengthInverse = inverseSqrt(dot(closestPoint, closestPoint)); - let normalizationFactor = a / saturate(a + (light.position_radius.w * 0.5 * LspecLengthInverse)); - let specularIntensity = normalizationFactor * normalizationFactor; - - var L: vec3 = closestPoint * LspecLengthInverse; // normalize() equivalent? - var H: vec3 = normalize(L + V); - var NoL: f32 = saturate(dot(N, L)); - var NoH: f32 = saturate(dot(N, H)); - var LoH: f32 = saturate(dot(L, H)); - - let specular_light = specular(F0, roughness, H, NdotV, NoL, NoH, LoH, specularIntensity); - - // Diffuse. - // Comes after specular since its NoL is used in the lighting equation. - L = normalize(light_to_frag); - H = normalize(L + V); - NoL = saturate(dot(N, L)); - NoH = saturate(dot(N, H)); - LoH = saturate(dot(L, H)); - - let diffuse = diffuseColor * Fd_Burley(roughness, NdotV, NoL, LoH); - - // See https://google.github.io/filament/Filament.html#mjx-eqn-pointLightLuminanceEquation - // Lout = f(v,l) Φ / { 4 π d^2 }⟨n⋅l⟩ - // where - // f(v,l) = (f_d(v,l) + f_r(v,l)) * light_color - // Φ is luminous power in lumens - // our rangeAttentuation = 1 / d^2 multiplied with an attenuation factor for smoothing at the edge of the non-physical maximum light radius - - // For a point light, luminous intensity, I, in lumens per steradian is given by: - // I = Φ / 4 π - // The derivation of this can be seen here: https://google.github.io/filament/Filament.html#mjx-eqn-pointLightLuminousPower - - // NOTE: light.color.rgb is premultiplied with light.intensity / 4 π (which would be the luminous intensity) on the CPU - - // TODO compensate for energy loss https://google.github.io/filament/Filament.html#materialsystem/improvingthebrdfs/energylossinspecularreflectance - - return ((diffuse + specular_light) * light.color_inverse_square_range.rgb) * (rangeAttenuation * NoL); -} - -fn directional_light(light: DirectionalLight, roughness: f32, NdotV: f32, normal: vec3, view: vec3, R: vec3, F0: vec3, diffuseColor: vec3) -> vec3 { - let incident_light = light.direction_to_light.xyz; - - let half_vector = normalize(incident_light + view); - let NoL = saturate(dot(normal, incident_light)); - let NoH = saturate(dot(normal, half_vector)); - let LoH = saturate(dot(incident_light, half_vector)); - - let diffuse = diffuseColor * Fd_Burley(roughness, NdotV, NoL, LoH); - let specularIntensity = 1.0; - let specular_light = specular(F0, roughness, half_vector, NdotV, NoL, NoH, LoH, specularIntensity); - - return (specular_light + diffuse) * light.color.rgb * NoL; -} - -fn fetch_point_shadow(light_id: u32, frag_position: vec4, surface_normal: vec3) -> f32 { - let light = point_lights.data[light_id]; - - // because the shadow maps align with the axes and the frustum planes are at 45 degrees - // we can get the worldspace depth by taking the largest absolute axis - let surface_to_light = light.position_radius.xyz - frag_position.xyz; - let surface_to_light_abs = abs(surface_to_light); - let distance_to_light = max(surface_to_light_abs.x, max(surface_to_light_abs.y, surface_to_light_abs.z)); - - // The normal bias here is already scaled by the texel size at 1 world unit from the light. - // The texel size increases proportionally with distance from the light so multiplying by - // distance to light scales the normal bias to the texel size at the fragment distance. - let normal_offset = light.shadow_normal_bias * distance_to_light * surface_normal.xyz; - let depth_offset = light.shadow_depth_bias * normalize(surface_to_light.xyz); - let offset_position = frag_position.xyz + normal_offset + depth_offset; - - // similar largest-absolute-axis trick as above, but now with the offset fragment position - let frag_ls = light.position_radius.xyz - offset_position.xyz; - let abs_position_ls = abs(frag_ls); - let major_axis_magnitude = max(abs_position_ls.x, max(abs_position_ls.y, abs_position_ls.z)); - - // NOTE: These simplifications come from multiplying: - // projection * vec4(0, 0, -major_axis_magnitude, 1.0) - // and keeping only the terms that have any impact on the depth. - // Projection-agnostic approach: - let zw = -major_axis_magnitude * light.projection_lr.xy + light.projection_lr.zw; - let depth = zw.x / zw.y; - - // do the lookup, using HW PCF and comparison - // NOTE: Due to the non-uniform control flow above, we must use the Level variant of - // textureSampleCompare to avoid undefined behaviour due to some of the fragments in - // a quad (2x2 fragments) being processed not being sampled, and this messing with - // mip-mapping functionality. The shadow maps have no mipmaps so Level just samples - // from LOD 0. -#ifdef NO_ARRAY_TEXTURES_SUPPORT - return textureSampleCompare(point_shadow_textures, point_shadow_textures_sampler, frag_ls, depth); -#else - return textureSampleCompareLevel(point_shadow_textures, point_shadow_textures_sampler, frag_ls, i32(light_id), depth); -#endif -} - -fn fetch_directional_shadow(light_id: u32, frag_position: vec4, surface_normal: vec3) -> f32 { - let light = lights.directional_lights[light_id]; - - // The normal bias is scaled to the texel size. - let normal_offset = light.shadow_normal_bias * surface_normal.xyz; - let depth_offset = light.shadow_depth_bias * light.direction_to_light.xyz; - let offset_position = vec4(frag_position.xyz + normal_offset + depth_offset, frag_position.w); - - let offset_position_clip = light.view_projection * offset_position; - if (offset_position_clip.w <= 0.0) { - return 1.0; - } - let offset_position_ndc = offset_position_clip.xyz / offset_position_clip.w; - // No shadow outside the orthographic projection volume - if (any(offset_position_ndc.xy < vec2(-1.0)) || offset_position_ndc.z < 0.0 - || any(offset_position_ndc > vec3(1.0))) { - return 1.0; - } - - // compute texture coordinates for shadow lookup, compensating for the Y-flip difference - // between the NDC and texture coordinates - let flip_correction = vec2(0.5, -0.5); - let light_local = offset_position_ndc.xy * flip_correction + vec2(0.5, 0.5); - - let depth = offset_position_ndc.z; - // do the lookup, using HW PCF and comparison - // NOTE: Due to non-uniform control flow above, we must use the level variant of the texture - // sampler to avoid use of implicit derivatives causing possible undefined behavior. -#ifdef NO_ARRAY_TEXTURES_SUPPORT - return textureSampleCompareLevel(directional_shadow_textures, directional_shadow_textures_sampler, light_local, depth); -#else - return textureSampleCompareLevel(directional_shadow_textures, directional_shadow_textures_sampler, light_local, i32(light_id), depth); -#endif -} - -fn hsv2rgb(hue: f32, saturation: f32, value: f32) -> vec3 { - let rgb = clamp( - abs( - ((hue * 6.0 + vec3(0.0, 4.0, 2.0)) % 6.0) - 3.0 - ) - 1.0, - vec3(0.0), - vec3(1.0) - ); - - return value * mix( vec3(1.0), rgb, vec3(saturation)); -} - -fn random1D(s: f32) -> f32 { - return fract(sin(s * 12.9898) * 43758.5453123); -} +#import bevy_pbr::utils +#import bevy_pbr::clustered_forward +#import bevy_pbr::lighting +#import bevy_pbr::shadows struct FragmentInput { [[builtin(front_facing)]] is_front: bool; @@ -588,40 +187,13 @@ fn fragment(in: FragmentInput) -> [[location(0)]] vec4 { emissive.rgb * output_color.a, output_color.a); - // Cluster allocation debug (using 'over' alpha blending) -#ifdef CLUSTERED_FORWARD_DEBUG_Z_SLICES - // NOTE: This debug mode visualises the z-slices - let cluster_overlay_alpha = 0.1; - var z_slice: u32 = view_z_to_z_slice(view_z, is_orthographic); - // A hack to make the colors alternate a bit more - if ((z_slice & 1u) == 1u) { - z_slice = z_slice + lights.cluster_dimensions.z / 2u; - } - let slice_color = hsv2rgb(f32(z_slice) / f32(lights.cluster_dimensions.z + 1u), 1.0, 0.5); - output_color = vec4( - (1.0 - cluster_overlay_alpha) * output_color.rgb + cluster_overlay_alpha * slice_color, - output_color.a + output_color = cluster_debug_visualization( + output_color, + view_z, + is_orthographic, + offset_and_count, + cluster_index, ); -#endif // CLUSTERED_FORWARD_DEBUG_Z_SLICES -#ifdef CLUSTERED_FORWARD_DEBUG_CLUSTER_LIGHT_COMPLEXITY - // NOTE: This debug mode visualises the number of lights within the cluster that contains - // the fragment. It shows a sort of lighting complexity measure. - let cluster_overlay_alpha = 0.1; - let max_light_complexity_per_cluster = 64.0; - output_color.r = (1.0 - cluster_overlay_alpha) * output_color.r - + cluster_overlay_alpha * smoothStep(0.0, max_light_complexity_per_cluster, f32(offset_and_count[1])); - output_color.g = (1.0 - cluster_overlay_alpha) * output_color.g - + cluster_overlay_alpha * (1.0 - smoothStep(0.0, max_light_complexity_per_cluster, f32(offset_and_count[1]))); -#endif // CLUSTERED_FORWARD_DEBUG_CLUSTER_LIGHT_COMPLEXITY -#ifdef CLUSTERED_FORWARD_DEBUG_CLUSTER_COHERENCY - // NOTE: Visualizes the cluster to which the fragment belongs - let cluster_overlay_alpha = 0.1; - let cluster_color = hsv2rgb(random1D(f32(cluster_index)), 1.0, 0.5); - output_color = vec4( - (1.0 - cluster_overlay_alpha) * output_color.rgb + cluster_overlay_alpha * cluster_color, - output_color.a - ); -#endif // CLUSTERED_FORWARD_DEBUG_CLUSTER_COHERENCY // tone_mapping output_color = vec4(reinhard_luminance(output_color.rgb), output_color.a); diff --git a/crates/bevy_pbr/src/render/pbr_lighting.wgsl b/crates/bevy_pbr/src/render/pbr_lighting.wgsl new file mode 100644 index 0000000000..79818bc837 --- /dev/null +++ b/crates/bevy_pbr/src/render/pbr_lighting.wgsl @@ -0,0 +1,255 @@ +#define_import_path bevy_pbr::lighting + +// From the Filament design doc +// https://google.github.io/filament/Filament.html#table_symbols +// Symbol Definition +// v View unit vector +// l Incident light unit vector +// n Surface normal unit vector +// h Half unit vector between l and v +// f BRDF +// f_d Diffuse component of a BRDF +// f_r Specular component of a BRDF +// α Roughness, remapped from using input perceptualRoughness +// σ Diffuse reflectance +// Ω Spherical domain +// f0 Reflectance at normal incidence +// f90 Reflectance at grazing angle +// χ+(a) Heaviside function (1 if a>0 and 0 otherwise) +// nior Index of refraction (IOR) of an interface +// ⟨n⋅l⟩ Dot product clamped to [0..1] +// ⟨a⟩ Saturated value (clamped to [0..1]) + +// The Bidirectional Reflectance Distribution Function (BRDF) describes the surface response of a standard material +// and consists of two components, the diffuse component (f_d) and the specular component (f_r): +// f(v,l) = f_d(v,l) + f_r(v,l) +// +// The form of the microfacet model is the same for diffuse and specular +// f_r(v,l) = f_d(v,l) = 1 / { |n⋅v||n⋅l| } ∫_Ω D(m,α) G(v,l,m) f_m(v,l,m) (v⋅m) (l⋅m) dm +// +// In which: +// D, also called the Normal Distribution Function (NDF) models the distribution of the microfacets +// G models the visibility (or occlusion or shadow-masking) of the microfacets +// f_m is the microfacet BRDF and differs between specular and diffuse components +// +// The above integration needs to be approximated. + +// distanceAttenuation is simply the square falloff of light intensity +// combined with a smooth attenuation at the edge of the light radius +// +// light radius is a non-physical construct for efficiency purposes, +// because otherwise every light affects every fragment in the scene +fn getDistanceAttenuation(distanceSquare: f32, inverseRangeSquared: f32) -> f32 { + let factor = distanceSquare * inverseRangeSquared; + let smoothFactor = saturate(1.0 - factor * factor); + let attenuation = smoothFactor * smoothFactor; + return attenuation * 1.0 / max(distanceSquare, 0.0001); +} + +// Normal distribution function (specular D) +// Based on https://google.github.io/filament/Filament.html#citation-walter07 + +// D_GGX(h,α) = α^2 / { π ((n⋅h)^2 (α2−1) + 1)^2 } + +// Simple implementation, has precision problems when using fp16 instead of fp32 +// see https://google.github.io/filament/Filament.html#listing_speculardfp16 +fn D_GGX(roughness: f32, NoH: f32, h: vec3) -> f32 { + let oneMinusNoHSquared = 1.0 - NoH * NoH; + let a = NoH * roughness; + let k = roughness / (oneMinusNoHSquared + a * a); + let d = k * k * (1.0 / PI); + return d; +} + +// Visibility function (Specular G) +// V(v,l,a) = G(v,l,α) / { 4 (n⋅v) (n⋅l) } +// such that f_r becomes +// f_r(v,l) = D(h,α) V(v,l,α) F(v,h,f0) +// where +// V(v,l,α) = 0.5 / { n⋅l sqrt((n⋅v)^2 (1−α2) + α2) + n⋅v sqrt((n⋅l)^2 (1−α2) + α2) } +// Note the two sqrt's, that may be slow on mobile, see https://google.github.io/filament/Filament.html#listing_approximatedspecularv +fn V_SmithGGXCorrelated(roughness: f32, NoV: f32, NoL: f32) -> f32 { + let a2 = roughness * roughness; + let lambdaV = NoL * sqrt((NoV - a2 * NoV) * NoV + a2); + let lambdaL = NoV * sqrt((NoL - a2 * NoL) * NoL + a2); + let v = 0.5 / (lambdaV + lambdaL); + return v; +} + +// Fresnel function +// see https://google.github.io/filament/Filament.html#citation-schlick94 +// F_Schlick(v,h,f_0,f_90) = f_0 + (f_90 − f_0) (1 − v⋅h)^5 +fn F_Schlick_vec(f0: vec3, f90: f32, VoH: f32) -> vec3 { + // not using mix to keep the vec3 and float versions identical + return f0 + (f90 - f0) * pow(1.0 - VoH, 5.0); +} + +fn F_Schlick(f0: f32, f90: f32, VoH: f32) -> f32 { + // not using mix to keep the vec3 and float versions identical + return f0 + (f90 - f0) * pow(1.0 - VoH, 5.0); +} + +fn fresnel(f0: vec3, LoH: f32) -> vec3 { + // f_90 suitable for ambient occlusion + // see https://google.github.io/filament/Filament.html#lighting/occlusion + let f90 = saturate(dot(f0, vec3(50.0 * 0.33))); + return F_Schlick_vec(f0, f90, LoH); +} + +// Specular BRDF +// https://google.github.io/filament/Filament.html#materialsystem/specularbrdf + +// Cook-Torrance approximation of the microfacet model integration using Fresnel law F to model f_m +// f_r(v,l) = { D(h,α) G(v,l,α) F(v,h,f0) } / { 4 (n⋅v) (n⋅l) } +fn specular(f0: vec3, roughness: f32, h: vec3, NoV: f32, NoL: f32, + NoH: f32, LoH: f32, specularIntensity: f32) -> vec3 { + let D = D_GGX(roughness, NoH, h); + let V = V_SmithGGXCorrelated(roughness, NoV, NoL); + let F = fresnel(f0, LoH); + + return (specularIntensity * D * V) * F; +} + +// Diffuse BRDF +// https://google.github.io/filament/Filament.html#materialsystem/diffusebrdf +// fd(v,l) = σ/π * 1 / { |n⋅v||n⋅l| } ∫Ω D(m,α) G(v,l,m) (v⋅m) (l⋅m) dm +// +// simplest approximation +// float Fd_Lambert() { +// return 1.0 / PI; +// } +// +// vec3 Fd = diffuseColor * Fd_Lambert(); +// +// Disney approximation +// See https://google.github.io/filament/Filament.html#citation-burley12 +// minimal quality difference +fn Fd_Burley(roughness: f32, NoV: f32, NoL: f32, LoH: f32) -> f32 { + let f90 = 0.5 + 2.0 * roughness * LoH * LoH; + let lightScatter = F_Schlick(1.0, f90, NoL); + let viewScatter = F_Schlick(1.0, f90, NoV); + return lightScatter * viewScatter * (1.0 / PI); +} + +// From https://www.unrealengine.com/en-US/blog/physically-based-shading-on-mobile +fn EnvBRDFApprox(f0: vec3, perceptual_roughness: f32, NoV: f32) -> vec3 { + let c0 = vec4(-1.0, -0.0275, -0.572, 0.022); + let c1 = vec4(1.0, 0.0425, 1.04, -0.04); + let r = perceptual_roughness * c0 + c1; + let a004 = min(r.x * r.x, exp2(-9.28 * NoV)) * r.x + r.y; + let AB = vec2(-1.04, 1.04) * a004 + r.zw; + return f0 * AB.x + AB.y; +} + +fn perceptualRoughnessToRoughness(perceptualRoughness: f32) -> f32 { + // clamp perceptual roughness to prevent precision problems + // According to Filament design 0.089 is recommended for mobile + // Filament uses 0.045 for non-mobile + let clampedPerceptualRoughness = clamp(perceptualRoughness, 0.089, 1.0); + return clampedPerceptualRoughness * clampedPerceptualRoughness; +} + +// from https://64.github.io/tonemapping/ +// reinhard on RGB oversaturates colors +fn reinhard(color: vec3) -> vec3 { + return color / (1.0 + color); +} + +fn reinhard_extended(color: vec3, max_white: f32) -> vec3 { + let numerator = color * (1.0 + (color / vec3(max_white * max_white))); + return numerator / (1.0 + color); +} + +// luminance coefficients from Rec. 709. +// https://en.wikipedia.org/wiki/Rec._709 +fn luminance(v: vec3) -> f32 { + return dot(v, vec3(0.2126, 0.7152, 0.0722)); +} + +fn change_luminance(c_in: vec3, l_out: f32) -> vec3 { + let l_in = luminance(c_in); + return c_in * (l_out / l_in); +} + +fn reinhard_luminance(color: vec3) -> vec3 { + let l_old = luminance(color); + let l_new = l_old / (1.0 + l_old); + return change_luminance(color, l_new); +} + +fn reinhard_extended_luminance(color: vec3, max_white_l: f32) -> vec3 { + let l_old = luminance(color); + let numerator = l_old * (1.0 + (l_old / (max_white_l * max_white_l))); + let l_new = numerator / (1.0 + l_old); + return change_luminance(color, l_new); +} + +fn point_light( + world_position: vec3, light: PointLight, roughness: f32, NdotV: f32, N: vec3, V: vec3, + R: vec3, F0: vec3, diffuseColor: vec3 +) -> vec3 { + let light_to_frag = light.position_radius.xyz - world_position.xyz; + let distance_square = dot(light_to_frag, light_to_frag); + let rangeAttenuation = + getDistanceAttenuation(distance_square, light.color_inverse_square_range.w); + + // Specular. + // Representative Point Area Lights. + // see http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf p14-16 + let a = roughness; + let centerToRay = dot(light_to_frag, R) * R - light_to_frag; + let closestPoint = light_to_frag + centerToRay * saturate(light.position_radius.w * inverseSqrt(dot(centerToRay, centerToRay))); + let LspecLengthInverse = inverseSqrt(dot(closestPoint, closestPoint)); + let normalizationFactor = a / saturate(a + (light.position_radius.w * 0.5 * LspecLengthInverse)); + let specularIntensity = normalizationFactor * normalizationFactor; + + var L: vec3 = closestPoint * LspecLengthInverse; // normalize() equivalent? + var H: vec3 = normalize(L + V); + var NoL: f32 = saturate(dot(N, L)); + var NoH: f32 = saturate(dot(N, H)); + var LoH: f32 = saturate(dot(L, H)); + + let specular_light = specular(F0, roughness, H, NdotV, NoL, NoH, LoH, specularIntensity); + + // Diffuse. + // Comes after specular since its NoL is used in the lighting equation. + L = normalize(light_to_frag); + H = normalize(L + V); + NoL = saturate(dot(N, L)); + NoH = saturate(dot(N, H)); + LoH = saturate(dot(L, H)); + + let diffuse = diffuseColor * Fd_Burley(roughness, NdotV, NoL, LoH); + + // See https://google.github.io/filament/Filament.html#mjx-eqn-pointLightLuminanceEquation + // Lout = f(v,l) Φ / { 4 π d^2 }⟨n⋅l⟩ + // where + // f(v,l) = (f_d(v,l) + f_r(v,l)) * light_color + // Φ is luminous power in lumens + // our rangeAttentuation = 1 / d^2 multiplied with an attenuation factor for smoothing at the edge of the non-physical maximum light radius + + // For a point light, luminous intensity, I, in lumens per steradian is given by: + // I = Φ / 4 π + // The derivation of this can be seen here: https://google.github.io/filament/Filament.html#mjx-eqn-pointLightLuminousPower + + // NOTE: light.color.rgb is premultiplied with light.intensity / 4 π (which would be the luminous intensity) on the CPU + + // TODO compensate for energy loss https://google.github.io/filament/Filament.html#materialsystem/improvingthebrdfs/energylossinspecularreflectance + + return ((diffuse + specular_light) * light.color_inverse_square_range.rgb) * (rangeAttenuation * NoL); +} + +fn directional_light(light: DirectionalLight, roughness: f32, NdotV: f32, normal: vec3, view: vec3, R: vec3, F0: vec3, diffuseColor: vec3) -> vec3 { + let incident_light = light.direction_to_light.xyz; + + let half_vector = normalize(incident_light + view); + let NoL = saturate(dot(normal, incident_light)); + let NoH = saturate(dot(normal, half_vector)); + let LoH = saturate(dot(incident_light, half_vector)); + + let diffuse = diffuseColor * Fd_Burley(roughness, NdotV, NoL, LoH); + let specularIntensity = 1.0; + let specular_light = specular(F0, roughness, half_vector, NdotV, NoL, NoH, LoH, specularIntensity); + + return (specular_light + diffuse) * light.color.rgb * NoL; +} diff --git a/crates/bevy_pbr/src/render/shadows.wgsl b/crates/bevy_pbr/src/render/shadows.wgsl new file mode 100644 index 0000000000..9cc2c7e84d --- /dev/null +++ b/crates/bevy_pbr/src/render/shadows.wgsl @@ -0,0 +1,77 @@ +#define_import_path bevy_pbr::shadows + +fn fetch_point_shadow(light_id: u32, frag_position: vec4, surface_normal: vec3) -> f32 { + let light = point_lights.data[light_id]; + + // because the shadow maps align with the axes and the frustum planes are at 45 degrees + // we can get the worldspace depth by taking the largest absolute axis + let surface_to_light = light.position_radius.xyz - frag_position.xyz; + let surface_to_light_abs = abs(surface_to_light); + let distance_to_light = max(surface_to_light_abs.x, max(surface_to_light_abs.y, surface_to_light_abs.z)); + + // The normal bias here is already scaled by the texel size at 1 world unit from the light. + // The texel size increases proportionally with distance from the light so multiplying by + // distance to light scales the normal bias to the texel size at the fragment distance. + let normal_offset = light.shadow_normal_bias * distance_to_light * surface_normal.xyz; + let depth_offset = light.shadow_depth_bias * normalize(surface_to_light.xyz); + let offset_position = frag_position.xyz + normal_offset + depth_offset; + + // similar largest-absolute-axis trick as above, but now with the offset fragment position + let frag_ls = light.position_radius.xyz - offset_position.xyz; + let abs_position_ls = abs(frag_ls); + let major_axis_magnitude = max(abs_position_ls.x, max(abs_position_ls.y, abs_position_ls.z)); + + // NOTE: These simplifications come from multiplying: + // projection * vec4(0, 0, -major_axis_magnitude, 1.0) + // and keeping only the terms that have any impact on the depth. + // Projection-agnostic approach: + let zw = -major_axis_magnitude * light.projection_lr.xy + light.projection_lr.zw; + let depth = zw.x / zw.y; + + // do the lookup, using HW PCF and comparison + // NOTE: Due to the non-uniform control flow above, we must use the Level variant of + // textureSampleCompare to avoid undefined behaviour due to some of the fragments in + // a quad (2x2 fragments) being processed not being sampled, and this messing with + // mip-mapping functionality. The shadow maps have no mipmaps so Level just samples + // from LOD 0. +#ifdef NO_ARRAY_TEXTURES_SUPPORT + return textureSampleCompare(point_shadow_textures, point_shadow_textures_sampler, frag_ls, depth); +#else + return textureSampleCompareLevel(point_shadow_textures, point_shadow_textures_sampler, frag_ls, i32(light_id), depth); +#endif +} + +fn fetch_directional_shadow(light_id: u32, frag_position: vec4, surface_normal: vec3) -> f32 { + let light = lights.directional_lights[light_id]; + + // The normal bias is scaled to the texel size. + let normal_offset = light.shadow_normal_bias * surface_normal.xyz; + let depth_offset = light.shadow_depth_bias * light.direction_to_light.xyz; + let offset_position = vec4(frag_position.xyz + normal_offset + depth_offset, frag_position.w); + + let offset_position_clip = light.view_projection * offset_position; + if (offset_position_clip.w <= 0.0) { + return 1.0; + } + let offset_position_ndc = offset_position_clip.xyz / offset_position_clip.w; + // No shadow outside the orthographic projection volume + if (any(offset_position_ndc.xy < vec2(-1.0)) || offset_position_ndc.z < 0.0 + || any(offset_position_ndc > vec3(1.0))) { + return 1.0; + } + + // compute texture coordinates for shadow lookup, compensating for the Y-flip difference + // between the NDC and texture coordinates + let flip_correction = vec2(0.5, -0.5); + let light_local = offset_position_ndc.xy * flip_correction + vec2(0.5, 0.5); + + let depth = offset_position_ndc.z; + // do the lookup, using HW PCF and comparison + // NOTE: Due to non-uniform control flow above, we must use the level variant of the texture + // sampler to avoid use of implicit derivatives causing possible undefined behavior. +#ifdef NO_ARRAY_TEXTURES_SUPPORT + return textureSampleCompareLevel(directional_shadow_textures, directional_shadow_textures_sampler, light_local, depth); +#else + return textureSampleCompareLevel(directional_shadow_textures, directional_shadow_textures_sampler, light_local, i32(light_id), depth); +#endif +} diff --git a/crates/bevy_pbr/src/render/utils.wgsl b/crates/bevy_pbr/src/render/utils.wgsl new file mode 100644 index 0000000000..ac13af027d --- /dev/null +++ b/crates/bevy_pbr/src/render/utils.wgsl @@ -0,0 +1,23 @@ +#define_import_path bevy_pbr::utils + +let PI: f32 = 3.141592653589793; + +fn saturate(value: f32) -> f32 { + return clamp(value, 0.0, 1.0); +} + +fn hsv2rgb(hue: f32, saturation: f32, value: f32) -> vec3 { + let rgb = clamp( + abs( + ((hue * 6.0 + vec3(0.0, 4.0, 2.0)) % 6.0) - 3.0 + ) - 1.0, + vec3(0.0), + vec3(1.0) + ); + + return value * mix( vec3(1.0), rgb, vec3(saturation)); +} + +fn random1D(s: f32) -> f32 { + return fract(sin(s * 12.9898) * 43758.5453123); +}