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Factor out up-choice in shadow cubemap sampling orthonormalize

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atlas 2025-07-09 00:33:16 -04:00
parent 0ee937784e
commit d1fce0d517
2 changed files with 9 additions and 19 deletions
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18
crates/bevy_pbr/src/render/shadow_sampling.wgsl
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@ -422,11 +422,7 @@ fn sample_shadow_cubemap_gaussian(
) -> f32 {
// Create an orthonormal basis so we can apply a 2D sampling pattern to a
// cubemap.
var up = vec3(0.0, 1.0, 0.0);
if (dot(up, normalize(light_local)) > 0.99) {
up = vec3(1.0, 0.0, 0.0); // Avoid creating a degenerate basis.
}
let basis = orthonormalize(light_local, up) * scale * distance_to_light;
let basis = orthonormalize(normalize(light_local)) * scale * distance_to_light;
var sum: f32 = 0.0;
sum += sample_shadow_cubemap_at_offset(
@ -469,11 +465,7 @@ fn sample_shadow_cubemap_jittered(
) -> f32 {
// Create an orthonormal basis so we can apply a 2D sampling pattern to a
// cubemap.
var up = vec3(0.0, 1.0, 0.0);
if (dot(up, normalize(light_local)) > 0.99) {
up = vec3(1.0, 0.0, 0.0); // Avoid creating a degenerate basis.
}
let basis = orthonormalize(light_local, up) * scale * distance_to_light;
let basis = orthonormalize(normalize(light_local)) * scale * distance_to_light;
let rotation_matrix = random_rotation_matrix(vec2(1.0), temporal);
@ -553,11 +545,7 @@ fn search_for_blockers_in_shadow_cubemap(
) -> f32 {
// Create an orthonormal basis so we can apply a 2D sampling pattern to a
// cubemap.
var up = vec3(0.0, 1.0, 0.0);
if (dot(up, normalize(light_local)) > 0.99) {
up = vec3(1.0, 0.0, 0.0); // Avoid creating a degenerate basis.
}
let basis = orthonormalize(light_local, up) * scale * distance_to_light;
let basis = orthonormalize(normalize(light_local)) * scale * distance_to_light;
var sum: vec2<f32> = vec2(0.0);
sum += search_for_blockers_in_shadow_cubemap_at_offset(

10
crates/bevy_render/src/maths.wgsl
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@ -63,14 +63,16 @@ fn mat4x4_to_mat3x3(m: mat4x4<f32>) -> mat3x3<f32> {
return mat3x3<f32>(m[0].xyz, m[1].xyz, m[2].xyz);
}
// Creates an orthonormal basis given a Z vector and an up vector (which becomes
// Y after orthonormalization).
// Creates an orthonormal basis given a normalized Z vector.
//
// The results are equivalent to the Gram-Schmidt process [1].
//
// [1]: https://math.stackexchange.com/a/1849294
fn orthonormalize(z_unnormalized: vec3<f32>, up: vec3<f32>) -> mat3x3<f32> {
let z_basis = normalize(z_unnormalized);
fn orthonormalize(z_basis: vec3<f32>) -> mat3x3<f32> {
var up = vec3(0.0, 1.0, 0.0);
if (dot(up, z_basis) > 0.99) {
up = vec3(1.0, 0.0, 0.0); // Avoid creating a degenerate basis.
}
let x_basis = normalize(cross(z_basis, up));
let y_basis = cross(z_basis, x_basis);
return mat3x3(x_basis, y_basis, z_basis);