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Receiver plane depth bias #10188

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Receiver plane depth bias #10188

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a8782ac
shadow_biases: Support moving the light position and resetting biases
superdump Oct 18, 2023
72e5f9c
Simplifications
robtfm Oct 19, 2023
4393d36
Use transparent background for text and every other sphere is on the …
superdump Oct 18, 2023
d791872
Implement Receiver Plane Depth Bias [Isidoro06]
superdump Oct 18, 2023
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118 changes: 95 additions & 23 deletions crates/bevy_pbr/src/render/shadow_sampling.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ fn sample_shadow_map_hardware(light_local: vec2<f32>, depth: f32, array_index: i
}

// https://web.archive.org/web/20230210095515/http://the-witness.net/news/2013/09/shadow-mapping-summary-part-1
fn sample_shadow_map_castano_thirteen(light_local: vec2<f32>, depth: f32, array_index: i32) -> f32 {
fn sample_shadow_map_castano_thirteen(light_local: vec2<f32>, depth: f32, receiver_plane_depth_bias: vec2<f32>, array_index: i32) -> f32 {
let shadow_map_size = vec2<f32>(textureDimensions(view_bindings::directional_shadow_textures));
let inv_shadow_map_size = 1.0 / shadow_map_size;

Expand Down Expand Up @@ -53,17 +53,26 @@ fn sample_shadow_map_castano_thirteen(light_local: vec2<f32>, depth: f32, array_

var sum = 0.0;

sum += uw0 * vw0 * sample_shadow_map_hardware(base_uv + (vec2(u0, v0) * inv_shadow_map_size), depth, array_index);
sum += uw1 * vw0 * sample_shadow_map_hardware(base_uv + (vec2(u1, v0) * inv_shadow_map_size), depth, array_index);
sum += uw2 * vw0 * sample_shadow_map_hardware(base_uv + (vec2(u2, v0) * inv_shadow_map_size), depth, array_index);

sum += uw0 * vw1 * sample_shadow_map_hardware(base_uv + (vec2(u0, v1) * inv_shadow_map_size), depth, array_index);
sum += uw1 * vw1 * sample_shadow_map_hardware(base_uv + (vec2(u1, v1) * inv_shadow_map_size), depth, array_index);
sum += uw2 * vw1 * sample_shadow_map_hardware(base_uv + (vec2(u2, v1) * inv_shadow_map_size), depth, array_index);

sum += uw0 * vw2 * sample_shadow_map_hardware(base_uv + (vec2(u0, v2) * inv_shadow_map_size), depth, array_index);
sum += uw1 * vw2 * sample_shadow_map_hardware(base_uv + (vec2(u1, v2) * inv_shadow_map_size), depth, array_index);
sum += uw2 * vw2 * sample_shadow_map_hardware(base_uv + (vec2(u2, v2) * inv_shadow_map_size), depth, array_index);
let sample_offset_u0_v0 = (vec2(u0, v0) * inv_shadow_map_size);
sum += uw0 * vw0 * sample_shadow_map_hardware(base_uv + sample_offset_u0_v0, depth + dot(sample_offset_u0_v0, receiver_plane_depth_bias), array_index);
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can we use a sample_shadow_map_offset(uv, offset, depth, bias, index) function?

let sample_offset_u1_v0 = (vec2(u1, v0) * inv_shadow_map_size);
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not directly related but we could make this a loop by putting uw, u, vw, v into vec3s (vecs don't have the constant index requirement apparently).

sum += uw1 * vw0 * sample_shadow_map_hardware(base_uv + sample_offset_u1_v0, depth + dot(sample_offset_u1_v0, receiver_plane_depth_bias), array_index);
let sample_offset_u2_v0 = (vec2(u2, v0) * inv_shadow_map_size);
sum += uw2 * vw0 * sample_shadow_map_hardware(base_uv + sample_offset_u2_v0, depth + dot(sample_offset_u2_v0, receiver_plane_depth_bias), array_index);

let sample_offset_u0_v1 = (vec2(u0, v1) * inv_shadow_map_size);
sum += uw0 * vw1 * sample_shadow_map_hardware(base_uv + sample_offset_u0_v1, depth + dot(sample_offset_u0_v1, receiver_plane_depth_bias), array_index);
let sample_offset_u1_v1 = (vec2(u1, v1) * inv_shadow_map_size);
sum += uw1 * vw1 * sample_shadow_map_hardware(base_uv + sample_offset_u1_v1, depth + dot(sample_offset_u1_v1, receiver_plane_depth_bias), array_index);
let sample_offset_u2_v1 = (vec2(u2, v1) * inv_shadow_map_size);
sum += uw2 * vw1 * sample_shadow_map_hardware(base_uv + sample_offset_u2_v1, depth + dot(sample_offset_u2_v1, receiver_plane_depth_bias), array_index);

let sample_offset_u0_v2 = (vec2(u0, v2) * inv_shadow_map_size);
sum += uw0 * vw2 * sample_shadow_map_hardware(base_uv + sample_offset_u0_v2, depth + dot(sample_offset_u0_v2, receiver_plane_depth_bias), array_index);
let sample_offset_u1_v2 = (vec2(u1, v2) * inv_shadow_map_size);
sum += uw1 * vw2 * sample_shadow_map_hardware(base_uv + sample_offset_u1_v2, depth + dot(sample_offset_u1_v2, receiver_plane_depth_bias), array_index);
let sample_offset_u2_v2 = (vec2(u2, v2) * inv_shadow_map_size);
sum += uw2 * vw2 * sample_shadow_map_hardware(base_uv + sample_offset_u2_v2, depth + dot(sample_offset_u2_v2, receiver_plane_depth_bias), array_index);

return sum * (1.0 / 144.0);
}
Expand All @@ -79,7 +88,7 @@ fn map(min1: f32, max1: f32, min2: f32, max2: f32, value: f32) -> f32 {
return min2 + (value - min1) * (max2 - min2) / (max1 - min1);
}

fn sample_shadow_map_jimenez_fourteen(light_local: vec2<f32>, depth: f32, array_index: i32, texel_size: f32) -> f32 {
fn sample_shadow_map_jimenez_fourteen(light_local: vec2<f32>, depth: f32, receiver_plane_depth_bias: vec2<f32>, array_index: i32, texel_size: f32) -> f32 {
let shadow_map_size = vec2<f32>(textureDimensions(view_bindings::directional_shadow_textures));

let random_angle = 2.0 * PI * interleaved_gradient_noise(light_local * shadow_map_size);
Expand All @@ -104,22 +113,85 @@ fn sample_shadow_map_jimenez_fourteen(light_local: vec2<f32>, depth: f32, array_
let sample_offset8 = (rotation_matrix * vec2( 0.1250, 0.0000)) * uv_offset_scale;

var sum = 0.0;
sum += sample_shadow_map_hardware(light_local + sample_offset1, depth, array_index);
sum += sample_shadow_map_hardware(light_local + sample_offset2, depth, array_index);
sum += sample_shadow_map_hardware(light_local + sample_offset3, depth, array_index);
sum += sample_shadow_map_hardware(light_local + sample_offset4, depth, array_index);
sum += sample_shadow_map_hardware(light_local + sample_offset5, depth, array_index);
sum += sample_shadow_map_hardware(light_local + sample_offset6, depth, array_index);
sum += sample_shadow_map_hardware(light_local + sample_offset7, depth, array_index);
sum += sample_shadow_map_hardware(light_local + sample_offset8, depth, array_index);
sum += sample_shadow_map_hardware(
light_local + sample_offset1,
depth + dot(sample_offset1, receiver_plane_depth_bias),
array_index,
);
sum += sample_shadow_map_hardware(
light_local + sample_offset2,
depth + dot(sample_offset2, receiver_plane_depth_bias),
array_index,
);
sum += sample_shadow_map_hardware(
light_local + sample_offset3,
depth + dot(sample_offset3, receiver_plane_depth_bias),
array_index,
);
sum += sample_shadow_map_hardware(
light_local + sample_offset4,
depth + dot(sample_offset4, receiver_plane_depth_bias),
array_index,
);
sum += sample_shadow_map_hardware(
light_local + sample_offset5,
depth + dot(sample_offset5, receiver_plane_depth_bias),
array_index,
);
sum += sample_shadow_map_hardware(
light_local + sample_offset6,
depth + dot(sample_offset6, receiver_plane_depth_bias),
array_index,
);
sum += sample_shadow_map_hardware(
light_local + sample_offset7,
depth + dot(sample_offset7, receiver_plane_depth_bias),
array_index,
);
sum += sample_shadow_map_hardware(
light_local + sample_offset8,
depth + dot(sample_offset8, receiver_plane_depth_bias),
array_index,
);
return sum / 8.0;
}

// Receiver Plane Depth Bias
// Isidoro06 - Slides 36-40 https://web.archive.org/web/20230309054654/http://developer.amd.com/wordpress/media/2012/10/Isidoro-ShadowMapping.pdf
// This implementation is from https://github.com/TheRealMJP/Shadows/blob/1a6d90c92ea58ccddb0dcd32b035c58b8f7784f4/Shadows/Mesh.hlsl#L102
fn compute_receiver_plane_depth_bias(tex_coord_dx: vec3<f32>, tex_coord_dy: vec3<f32>) -> vec2<f32> {
var bias_uv: vec2<f32> = vec2<f32>(
tex_coord_dy.y * tex_coord_dx.z - tex_coord_dx.y * tex_coord_dy.z,
tex_coord_dx.x * tex_coord_dy.z - tex_coord_dy.x * tex_coord_dx.z
);
bias_uv = bias_uv * 1.0 / ((tex_coord_dx.x * tex_coord_dy.y) - (tex_coord_dx.y * tex_coord_dy.x));
return bias_uv;
}

fn sample_shadow_map(light_local: vec2<f32>, depth: f32, array_index: i32, texel_size: f32) -> f32 {
#ifndef SHADOW_FILTER_METHOD_HARDWARE_2X2
let shadow_pos = vec3(light_local, depth);
let receiver_plane_depth_bias = compute_receiver_plane_depth_bias(
dpdx(shadow_pos),
dpdy(shadow_pos),
);
#endif

#ifdef SHADOW_FILTER_METHOD_CASTANO_13
return sample_shadow_map_castano_thirteen(light_local, depth, array_index);
return sample_shadow_map_castano_thirteen(
light_local,
depth,
receiver_plane_depth_bias,
array_index,
);
#else ifdef SHADOW_FILTER_METHOD_JIMENEZ_14
return sample_shadow_map_jimenez_fourteen(light_local, depth, array_index, texel_size);
return sample_shadow_map_jimenez_fourteen(
light_local,
depth,
receiver_plane_depth_bias,
array_index,
texel_size,
);
#else ifdef SHADOW_FILTER_METHOD_HARDWARE_2X2
return sample_shadow_map_hardware(light_local, depth, array_index);
#else
Expand Down
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