mirror of
https://github.com/bevyengine/bevy
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aa626e4f0b
# Objective - Prepare for streaming by storing vertex data per-meshlet, rather than per-mesh (this means duplicating vertices per-meshlet) - Compress vertex data to reduce the cost of this ## Solution The important parts are in from_mesh.rs, the changes to the Meshlet type in asset.rs, and the changes in meshlet_bindings.wgsl. Everything else is pretty secondary/boilerplate/straightforward changes. - Positions are quantized in centimeters with a user-provided power of 2 factor (ideally auto-determined, but that's a TODO for the future), encoded as an offset relative to the minimum value within the meshlet, and then stored as a packed list of bits using the minimum number of bits needed for each vertex position channel for that meshlet - E.g. quantize positions (lossly, throws away precision that's not needed leading to using less bits in the bitstream encoding) - Get the min/max quantized value of each X/Y/Z channel of the quantized positions within a meshlet - Encode values relative to the min value of the meshlet. E.g. convert from [min, max] to [0, max - min] - The new max value in the meshlet is (max - min), which only takes N bits, so we only need N bits to store each channel within the meshlet (lossless) - We can store the min value and that it takes N bits per channel in the meshlet metadata, and reconstruct the position from the bitstream - Normals are octahedral encoded and than snorm2x16 packed and stored as a single u32. - Would be better to implement the precise variant of octhedral encoding for extra precision (no extra decode cost), but decided to keep it simple for now and leave that as a followup - Tried doing a quantizing and bitstream encoding scheme like I did for positions, but struggled to get it smaller. Decided to go with this for simplicity for now - UVs are uncompressed and take a full 64bits per vertex which is expensive - In the future this should be improved - Tangents, as of the previous PR, are not explicitly stored and are instead derived from screen space gradients - While I'm here, split up MeshletMeshSaverLoader into two separate types Other future changes include implementing a smaller encoding of triangle data (3 u8 indices = 24 bits per triangle currently), and more disk-oriented compression schemes. References: * "A Deep Dive into UE5's Nanite Virtualized Geometry" https://advances.realtimerendering.com/s2021/Karis_Nanite_SIGGRAPH_Advances_2021_final.pdf#page=128 (also available on youtube) * "Towards Practical Meshlet Compression" https://arxiv.org/pdf/2404.06359 * "Vertex quantization in Omniforce Game Engine" https://daniilvinn.github.io/2024/05/04/omniforce-vertex-quantization.html ## Testing - Did you test these changes? If so, how? - Converted the stanford bunny, and rendered it with a debug material showing normals, and confirmed that it's identical to what's on main. EDIT: See additional testing in the comments below. - Are there any parts that need more testing? - Could use some more size comparisons on various meshes, and testing different quantization factors. Not sure if 4 is a good default. EDIT: See additional testing in the comments below. - Also did not test runtime performance of the shaders. EDIT: See additional testing in the comments below. - How can other people (reviewers) test your changes? Is there anything specific they need to know? - Use my unholy script, replacing the meshlet example https://paste.rs/7xQHk.rs (must make MeshletMesh fields pub instead of pub crate, must add lz4_flex as a dev-dependency) (must compile with meshlet and meshlet_processor features, mesh must have only positions, normals, and UVs, no vertex colors or tangents) --- ## Migration Guide - TBD by JMS55 at the end of the release
75 lines
2.5 KiB
TOML
75 lines
2.5 KiB
TOML
[package]
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name = "bevy_pbr"
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version = "0.15.0-dev"
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edition = "2021"
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description = "Adds PBR rendering to Bevy Engine"
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homepage = "https://bevyengine.org"
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repository = "https://github.com/bevyengine/bevy"
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license = "MIT OR Apache-2.0"
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keywords = ["bevy"]
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[features]
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webgl = []
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webgpu = []
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pbr_transmission_textures = []
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pbr_multi_layer_material_textures = []
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pbr_anisotropy_texture = []
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shader_format_glsl = ["bevy_render/shader_format_glsl"]
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trace = ["bevy_render/trace"]
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ios_simulator = ["bevy_render/ios_simulator"]
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# Enables the meshlet renderer for dense high-poly scenes (experimental)
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meshlet = ["dep:lz4_flex", "dep:thiserror", "dep:range-alloc", "dep:bevy_tasks"]
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# Enables processing meshes into meshlet meshes
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meshlet_processor = [
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"meshlet",
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"dep:meshopt",
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"dep:metis",
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"dep:itertools",
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"dep:bitvec",
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]
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[dependencies]
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# bevy
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bevy_app = { path = "../bevy_app", version = "0.15.0-dev" }
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bevy_asset = { path = "../bevy_asset", version = "0.15.0-dev" }
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bevy_color = { path = "../bevy_color", version = "0.15.0-dev" }
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bevy_core_pipeline = { path = "../bevy_core_pipeline", version = "0.15.0-dev" }
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bevy_derive = { path = "../bevy_derive", version = "0.15.0-dev" }
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bevy_ecs = { path = "../bevy_ecs", version = "0.15.0-dev" }
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bevy_math = { path = "../bevy_math", version = "0.15.0-dev" }
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bevy_reflect = { path = "../bevy_reflect", version = "0.15.0-dev", features = [
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"bevy",
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] }
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bevy_render = { path = "../bevy_render", version = "0.15.0-dev" }
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bevy_tasks = { path = "../bevy_tasks", version = "0.15.0-dev", optional = true }
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bevy_transform = { path = "../bevy_transform", version = "0.15.0-dev" }
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bevy_utils = { path = "../bevy_utils", version = "0.15.0-dev" }
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bevy_window = { path = "../bevy_window", version = "0.15.0-dev" }
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# other
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bitflags = "2.3"
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fixedbitset = "0.5"
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# meshlet
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lz4_flex = { version = "0.11", default-features = false, features = [
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"frame",
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], optional = true }
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thiserror = { version = "1", optional = true }
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range-alloc = { version = "0.1.3", optional = true }
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meshopt = { version = "0.3.0", optional = true }
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metis = { version = "0.2", optional = true }
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itertools = { version = "0.13", optional = true }
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bitvec = { version = "1", optional = true }
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# direct dependency required for derive macro
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bytemuck = { version = "1", features = ["derive", "must_cast"] }
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radsort = "0.1"
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smallvec = "1.6"
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nonmax = "0.5"
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static_assertions = "1"
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[lints]
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workspace = true
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[package.metadata.docs.rs]
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rustdoc-args = ["-Zunstable-options", "--generate-link-to-definition"]
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all-features = true
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