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feature: physically based bloom (#103)
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| Original file line number | Diff line number | Diff line change |
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| //! Physically based bloom. | ||
| //! | ||
| //! As described in [learnopengl.com's Physically Based Bloom article](https://learnopengl.com/Guest-Articles/2022/Phys.-Based-Bloom). | ||
| use crabslab::{Id, Slab, SlabItem}; | ||
| use glam::{UVec2, Vec2, Vec4, Vec4Swizzles}; | ||
| use spirv_std::{image::Image2d, spirv, Sampler}; | ||
|
|
||
| #[cfg(not(target_arch = "spirv"))] | ||
| mod cpu; | ||
| #[cfg(not(target_arch = "spirv"))] | ||
| pub use cpu::*; | ||
|
|
||
| #[derive(Clone, Copy, SlabItem)] | ||
| pub struct BloomConfig { | ||
| pub resolution: UVec2, | ||
| pub upsample_filter_radius: Vec2, | ||
| } | ||
|
|
||
| impl Default for BloomConfig { | ||
| fn default() -> Self { | ||
| Self { | ||
| resolution: UVec2::ONE, | ||
| upsample_filter_radius: Vec2::ONE, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| #[cfg(feature = "bloom_vertex")] | ||
| /// A passthru vertex shader to facilitate a bloom effect. | ||
| #[spirv(vertex)] | ||
| pub fn bloom_vertex( | ||
| #[spirv(vertex_index)] vertex_index: u32, | ||
| #[spirv(instance_index)] in_id: u32, | ||
| out_uv: &mut Vec2, | ||
| #[spirv(flat)] out_id: &mut u32, | ||
| #[spirv(position)] out_clip_pos: &mut Vec4, | ||
| ) { | ||
| let i = (vertex_index % 6) as usize; | ||
| *out_uv = crate::math::UV_COORD_QUAD_CCW[i]; | ||
| *out_clip_pos = crate::math::CLIP_SPACE_COORD_QUAD_CCW[i]; | ||
| *out_id = in_id; | ||
| } | ||
|
|
||
| #[cfg(feature = "bloom_downsample_fragment")] | ||
| /// Performs downsampling on a texture. | ||
| /// | ||
| /// As taken from Call Of Duty method - presented at ACM Siggraph 2014. | ||
| /// | ||
| /// This particular method was customly designed to eliminate | ||
| /// "pulsating artifacts and temporal stability issues". | ||
| #[spirv(fragment)] | ||
| pub fn bloom_downsample_fragment( | ||
| #[spirv(storage_buffer, descriptor_set = 0, binding = 0)] slab: &[u32], | ||
| // Remember to add bilinear minification filter for this texture! | ||
| // Remember to use a floating-point texture format (for HDR)! | ||
| // Remember to use edge clamping for this texture! | ||
| #[spirv(descriptor_set = 0, binding = 1)] texture: &Image2d, | ||
| #[spirv(descriptor_set = 0, binding = 2)] sampler: &Sampler, | ||
| in_uv: Vec2, | ||
| #[spirv(flat)] in_pixel_size_id: Id<Vec2>, | ||
| // frag_color | ||
| downsample: &mut Vec4, | ||
| ) { | ||
| use glam::Vec3; | ||
|
|
||
| let Vec2 { x, y } = slab.read(in_pixel_size_id); | ||
|
|
||
| // Take 13 samples around current texel: | ||
| // a - b - c | ||
| // - j - k - | ||
| // d - e - f | ||
| // - l - m - | ||
| // g - h - i | ||
| // === ('e' is the current texel) === | ||
| let a = texture.sample(*sampler, Vec2::new(in_uv.x - 2.0 * x, in_uv.y + 2.0 * y)); | ||
| let b = texture.sample(*sampler, Vec2::new(in_uv.x, in_uv.y + 2.0 * y)); | ||
| let c = texture.sample(*sampler, Vec2::new(in_uv.x + 2.0 * x, in_uv.y + 2.0 * y)); | ||
|
|
||
| let d = texture.sample(*sampler, Vec2::new(in_uv.x - 2.0 * x, in_uv.y)); | ||
| let e = texture.sample(*sampler, Vec2::new(in_uv.x, in_uv.y)); | ||
| let f = texture.sample(*sampler, Vec2::new(in_uv.x + 2.0 * x, in_uv.y)); | ||
|
|
||
| let g = texture.sample(*sampler, Vec2::new(in_uv.x - 2.0 * x, in_uv.y - 2.0 * y)); | ||
| let h = texture.sample(*sampler, Vec2::new(in_uv.x, in_uv.y - 2.0 * y)); | ||
| let i = texture.sample(*sampler, Vec2::new(in_uv.x + 2.0 * x, in_uv.y - 2.0 * y)); | ||
|
|
||
| let j = texture.sample(*sampler, Vec2::new(in_uv.x - x, in_uv.y + y)); | ||
| let k = texture.sample(*sampler, Vec2::new(in_uv.x + x, in_uv.y + y)); | ||
| let l = texture.sample(*sampler, Vec2::new(in_uv.x - x, in_uv.y - y)); | ||
| let m = texture.sample(*sampler, Vec2::new(in_uv.x + x, in_uv.y - y)); | ||
|
|
||
| // Apply weighted distribution: | ||
| // 0.5 + 0.125 + 0.125 + 0.125 + 0.125 = 1 | ||
| // a,b,d,e * 0.125 | ||
| // b,c,e,f * 0.125 | ||
| // d,e,g,h * 0.125 | ||
| // e,f,h,i * 0.125 | ||
| // j,k,l,m * 0.5 | ||
| // This shows 5 square areas that are being sampled. But some of them overlap, | ||
| // so to have an energy preserving downsample we need to make some adjustments. | ||
| // The weights are the distributed so that the sum of j,k,l,m (e.g.) | ||
| // contribute 0.5 to the final color output. The code below is written | ||
| // to effectively yield this sum. We get: | ||
| // 0.125*5 + 0.03125*4 + 0.0625*4 = 1 | ||
| let f1 = 0.125; | ||
| let f2 = 0.0625; | ||
| let f3 = 0.03125; | ||
| let center = e * f1; | ||
| let inner = (j + k + l + m) * f1; | ||
| let outer = (b + d + h + f) * f2; | ||
| let furthest = (a + c + g + i) * f3; | ||
| let min = Vec3::splat(f32::EPSILON).extend(1.0); | ||
| *downsample = (center + inner + outer + furthest).max(min); | ||
| } | ||
|
|
||
| #[cfg(feature = "bloom_upsample_fragment")] | ||
| /// This shader performs upsampling on a texture. | ||
| /// Taken from Call Of Duty method, presented at ACM Siggraph 2014. | ||
| #[spirv(fragment)] | ||
| pub fn bloom_upsample_fragment( | ||
| #[spirv(storage_buffer, descriptor_set = 0, binding = 0)] slab: &[u32], | ||
| // Remember to add bilinear minification filter for this texture! | ||
| // Remember to use a floating-point texture format (for HDR)! | ||
| // Remember to use edge clamping for this texture! | ||
| #[spirv(descriptor_set = 0, binding = 1)] texture: &Image2d, | ||
| #[spirv(descriptor_set = 0, binding = 2)] sampler: &Sampler, | ||
| in_uv: Vec2, | ||
| #[spirv(flat)] filter_radius_id: Id<Vec2>, | ||
| // frag_color | ||
| upsample: &mut Vec4, | ||
| ) { | ||
| // The filter kernel is applied with a radius, specified in texture | ||
| // coordinates, so that the radius will vary across mip resolutions. | ||
| let Vec2 { x, y } = slab.read(filter_radius_id); | ||
|
|
||
| // Take 9 samples around current texel: | ||
| // a - b - c | ||
| // d - e - f | ||
| // g - h - i | ||
| // === ('e' is the current texel) === | ||
| let a = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x - x, in_uv.y + y)) | ||
| .xyz(); | ||
| let b = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x, in_uv.y + y)) | ||
| .xyz(); | ||
| let c = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x + x, in_uv.y + y)) | ||
| .xyz(); | ||
|
|
||
| let d = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x - x, in_uv.y)) | ||
| .xyz(); | ||
| let e = texture.sample(*sampler, Vec2::new(in_uv.x, in_uv.y)).xyz(); | ||
| let f = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x + x, in_uv.y)) | ||
| .xyz(); | ||
|
|
||
| let g = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x - x, in_uv.y - y)) | ||
| .xyz(); | ||
| let h = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x, in_uv.y - y)) | ||
| .xyz(); | ||
| let i = texture | ||
| .sample(*sampler, Vec2::new(in_uv.x + x, in_uv.y - y)) | ||
| .xyz(); | ||
|
|
||
| // Apply weighted distribution, by using a 3x3 tent filter: | ||
| // 1 | 1 2 1 | | ||
| // -- * | 2 4 2 | | ||
| // 16 | 1 2 1 | | ||
| let mut sample = e * 4.0; | ||
| sample += (b + d + f + h) * 2.0; | ||
| sample += a + c + g + i; | ||
| sample *= 1.0 / 16.0; | ||
| *upsample = sample.extend(0.5); | ||
| } | ||
|
|
||
| #[cfg(feature = "bloom_mix_fragment")] | ||
| #[spirv(fragment)] | ||
| pub fn bloom_mix_fragment( | ||
| #[spirv(storage_buffer, descriptor_set = 0, binding = 0)] slab: &[u32], | ||
| #[spirv(descriptor_set = 0, binding = 1)] hdr_texture: &Image2d, | ||
| #[spirv(descriptor_set = 0, binding = 2)] hdr_sampler: &Sampler, | ||
| #[spirv(descriptor_set = 0, binding = 3)] bloom_texture: &Image2d, | ||
| #[spirv(descriptor_set = 0, binding = 4)] bloom_sampler: &Sampler, | ||
| in_uv: Vec2, | ||
| #[spirv(flat)] in_bloom_strength_id: Id<f32>, | ||
| frag_color: &mut Vec4, | ||
| ) { | ||
| let bloom_strength = slab.read(in_bloom_strength_id); | ||
| let hdr = hdr_texture.sample(*hdr_sampler, in_uv).xyz(); | ||
| let bloom = bloom_texture.sample(*bloom_sampler, in_uv).xyz(); | ||
| let color = hdr.lerp(bloom, bloom_strength); | ||
| *frag_color = color.extend(1.0) | ||
| } |
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