JMS55 af9c945f40 Screen Space Ambient Occlusion (SSAO) MVP (#7402) ...  # Objective - Add Screen space ambient occlusion (SSAO). SSAO approximates small-scale, local occlusion of _indirect_ diffuse light between objects. SSAO does not apply to direct lighting, such as point or directional lights. - This darkens creases, e.g. on staircases, and gives nice contact shadows where objects meet, giving entities a more "grounded" feel. - Closes https://github.com/bevyengine/bevy/issues/3632. ## Solution - Implement the GTAO algorithm. - https://www.activision.com/cdn/research/Practical_Real_Time_Strategies_for_Accurate_Indirect_Occlusion_NEW%20VERSION_COLOR.pdf - https://blog.selfshadow.com/publications/s2016-shading-course/activision/s2016_pbs_activision_occlusion.pdf - Source code heavily based on [Intel's XeGTAO](0d177ce06b/Source/Rendering/Shaders/XeGTAO.hlsli). - Add an SSAO bevy example. ## Algorithm Overview * Run a depth and normal prepass * Create downscaled mips of the depth texture (preprocess_depths pass) * GTAO pass - for each pixel, take several random samples from the depth+normal buffers, reconstruct world position, raytrace in screen space to estimate occlusion. Rather then doing completely random samples on a hemisphere, you choose random _slices_ of the hemisphere, and then can analytically compute the full occlusion of that slice. Also compute edges based on depth differences here. * Spatial denoise pass - bilateral blur, using edge detection to not blur over edges. This is the final SSAO result. * Main pass - if SSAO exists, sample the SSAO texture, and set occlusion to be the minimum of ssao/material occlusion. This then feeds into the rest of the PBR shader as normal. --- ## Future Improvements - Maybe remove the low quality preset for now (too noisy) - WebGPU fallback (see below) - Faster depth->world position (see reverted code) - Bent normals - Try interleaved gradient noise or spatiotemporal blue noise - Replace the spatial denoiser with a combined spatial+temporal denoiser - Render at half resolution and use a bilateral upsample - Better multibounce approximation (https://drive.google.com/file/d/1SyagcEVplIm2KkRD3WQYSO9O0Iyi1hfy/view) ## Far-Future Performance Improvements - F16 math (missing naga-wgsl support https://github.com/gfx-rs/naga/issues/1884) - Faster coordinate space conversion for normals - Faster depth mipchain creation (https://github.com/GPUOpen-Effects/FidelityFX-SPD) (wgpu/naga does not currently support subgroup ops) - Deinterleaved SSAO for better cache efficiency (https://developer.nvidia.com/sites/default/files/akamai/gameworks/samples/DeinterleavedTexturing.pdf) ## Other Interesting Papers - Visibility bitmask (https://link.springer.com/article/10.1007/s00371-022-02703-y, https://cdrinmatane.github.io/posts/cgspotlight-slides/) - Screen space diffuse lighting (https://github.com/Patapom/GodComplex/blob/master/Tests/TestHBIL/2018%20Mayaux%20-%20Horizon-Based%20Indirect%20Lighting%20(HBIL).pdf) ## Platform Support * SSAO currently does not work on DirectX12 due to issues with wgpu and naga: * https://github.com/gfx-rs/wgpu/pull/3798 * https://github.com/gfx-rs/naga/pull/2353 * SSAO currently does not work on WebGPU because r16float is not a valid storage texture format https://gpuweb.github.io/gpuweb/wgsl/#storage-texel-formats. We can fix this with a fallback to r32float. --- ## Changelog - Added ScreenSpaceAmbientOcclusionSettings, ScreenSpaceAmbientOcclusionQualityLevel, and ScreenSpaceAmbientOcclusionBundle --------- Co-authored-by: IceSentry <c.giguere42@gmail.com> Co-authored-by: IceSentry <IceSentry@users.noreply.github.com> Co-authored-by: Daniel Chia <danstryder@gmail.com> Co-authored-by: Elabajaba <Elabajaba@users.noreply.github.com> Co-authored-by: Robert Swain <robert.swain@gmail.com> Co-authored-by: robtfm <50659922+robtfm@users.noreply.github.com> Co-authored-by: Brandon Dyer <brandondyer64@gmail.com> Co-authored-by: Edgar Geier <geieredgar@gmail.com> Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>		2023-06-18 21:05:55 +00:00
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3d_gizmos.rs	Instanced line rendering for gizmos based on bevy_polyline (#8427)	2023-06-13 06:49:47 +00:00
3d_scene.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
3d_shapes.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
anti_aliasing.rs	standardize instructions in examples (#8478)	2023-04-26 19:52:31 +00:00
atmospheric_fog.rs	standardize instructions in examples (#8478)	2023-04-26 19:52:31 +00:00
blend_modes.rs	fix new clippy lints before they reach stable (#8700)	2023-05-29 07:23:50 +00:00
bloom_3d.rs	standardize instructions in examples (#8478)	2023-04-26 19:52:31 +00:00
fog.rs	Rename keys like LAlt to AltLeft (#8792)	2023-06-15 01:37:04 +00:00
lighting.rs	standardize instructions in examples (#8478)	2023-04-26 19:52:31 +00:00
lines.rs	reflect: stable type path v2 (#7184)	2023-06-05 20:31:20 +00:00
load_gltf.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
orthographic.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
parallax_mapping.rs	fix new clippy lints before they reach stable (#8700)	2023-05-29 07:23:50 +00:00
parenting.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
pbr.rs	add a default font (#8445)	2023-04-21 22:30:18 +00:00
render_to_texture.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
shadow_biases.rs	Rename keys like LAlt to AltLeft (#8792)	2023-06-15 01:37:04 +00:00
shadow_caster_receiver.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
skybox.rs	Rename keys like LAlt to AltLeft (#8792)	2023-06-15 01:37:04 +00:00
spherical_area_lights.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
split_screen.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
spotlight.rs	fix new clippy lints before they reach stable (#8700)	2023-05-29 07:23:50 +00:00
ssao.rs	Screen Space Ambient Occlusion (SSAO) MVP (#7402)	2023-06-18 21:05:55 +00:00
texture.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
tonemapping.rs	reflect: stable type path v2 (#7184)	2023-06-05 20:31:20 +00:00
transparency_3d.rs	Fixed several missing links in docs. (#8117)	2023-04-23 17:28:36 +00:00
two_passes.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
update_gltf_scene.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
vertex_colors.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00
wireframe.rs	Schedule-First: the new and improved add_systems (#8079)	2023-03-18 01:45:34 +00:00