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Fresnel should darken the SSR reflections instead of blending them with specular light.

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This commit is contained in:
mandryskowski 2023-07-26 13:39:10 +02:00
parent 202e4b2c1e
commit 5b2e54c17b
1 changed files with 29 additions and 18 deletions
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47
servers/rendering/renderer_rd/shaders/effects/screen_space_reflection.glsl
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@ -184,7 +184,7 @@ void main() {
vec4 test_normal_roughness = imageLoad(source_normal_roughness, test_pos);
vec3 test_normal = test_normal_roughness.xyz * 2.0 - 1.0;
test_normal = normalize(test_normal);
test_normal.y = -test_normal.y; //because this code reads flipped
test_normal.y = -test_normal.y; // Because this code reads flipped.
if (dot(ray_dir, test_normal) < 0.001) {
// if depth was surpassed
@ -203,6 +203,7 @@ void main() {
if (found) {
float margin_blend = 1.0;
vec2 final_pos = pos;
vec2 margin = vec2((params.screen_size.x + params.screen_size.y) * 0.05); // make a uniform margin
if (any(bvec4(lessThan(pos, vec2(0.0, 0.0)), greaterThan(pos, params.screen_size)))) {
@ -219,16 +220,40 @@ void main() {
//margin_blend = 1.0;
}
vec2 final_pos;
// Fade In / Fade Out
float grad = (steps_taken + 1.0) / float(params.num_steps);
float initial_fade = params.curve_fade_in == 0.0 ? 1.0 : pow(clamp(grad, 0.0, 1.0), params.curve_fade_in);
float fade = pow(clamp(1.0 - grad, 0.0, 1.0), params.distance_fade) * initial_fade;
// Ensure that precision errors do not introduce any fade. Even if it is just slightly below 1.0,
// strong specular light can leak through the reflection.
if (fade > 0.999) {
fade = 1.0;
}
// This is an ad-hoc term to fade out the SSR as roughness increases. Values used
// are meant to match the visual appearance of a ReflectionProbe.
float roughness_fade = smoothstep(0.4, 0.7, 1.0 - normal_roughness.w);
final_pos = pos;
vec4 final_color;
// Schlick term.
float metallic = texelFetch(source_metallic, ssC << 1, 0).w;
// F0 is the reflectance of normally incident light (perpendicular to the surface).
// Dielectric materials have a widely accepted default value of 0.04. We assume that metals reflect all light, so their F0 is 1.0.
float f0 = mix(0.04, 1.0, metallic);
float m = clamp(1.0 - dot(normal, -view_dir), 0.0, 1.0);
float m2 = m * m;
m = m2 * m2 * m; // pow(m,5)
float fresnel_term = f0 + (1.0 - f0) * m; // Fresnel Schlick term.
// The alpha value of final_color controls the blending with specular light in specular_merge.glsl.
// Note that the Fresnel term is multiplied with the RGB color instead of being a part of the alpha value.
// There is a key difference:
// - multiplying a term with RGB darkens the SSR light without introducing/taking away specular light.
// - combining a term into the Alpha value introduces specular light at the expense of the SSR light.
vec4 final_color = vec4(imageLoad(source_diffuse, ivec2(final_pos - 0.5)).rgb * fresnel_term, fade * margin_blend * roughness_fade);
imageStore(ssr_image, ssC, final_color);
#ifdef MODE_ROUGH
@ -259,20 +284,6 @@ void main() {
#endif // MODE_ROUGH
final_color = vec4(imageLoad(source_diffuse, ivec2(final_pos - 0.5)).rgb, fade * margin_blend * roughness_fade);
// Schlick term.
float metallic = texelFetch(source_metallic, ssC << 1, 0).w;
// F0 is the reflectance of normally incident light (perpendicular to the surface).
// Dielectric materials have a widely accepted default value of 0.04. We assume that metals reflect all light, so their F0 is 1.0.
float f0 = mix(0.04, 1.0, metallic);
float m = clamp(1.0 - dot(normal, -view_dir), 0.0, 1.0);
float m2 = m * m;
m = m2 * m2 * m; // pow(m,5)
final_color.a *= f0 + (1.0 - f0) * m; // Fresnel Schlick term.
imageStore(ssr_image, ssC, final_color);
} else {
#ifdef MODE_ROUGH
imageStore(blur_radius_image, ssC, vec4(0.0));