Move debanding into internal sky shader code so that it is applied after everything else.

This ensures that the debanding does not scale with exposure or any other effect.

3 files changed, 15 insertions, 0 deletions

diff --git a/servers/rendering/renderer_rd/environment/sky.cpp b/servers/rendering/renderer_rd/environment/sky.cpp
index 65d1d9e705..ceba43ae8f 100644
--- a/servers/rendering/renderer_rd/environment/sky.cpp
+++ b/servers/rendering/renderer_rd/environment/sky.cpp
@@ -907,6 +907,7 @@ void SkyRD::init() {
 		actions.usage_defines["HALF_RES_COLOR"] = "\n#define USES_HALF_RES_COLOR\n";
 		actions.usage_defines["QUARTER_RES_COLOR"] = "\n#define USES_QUARTER_RES_COLOR\n";
 		actions.render_mode_defines["disable_fog"] = "#define DISABLE_FOG\n";
+		actions.render_mode_defines["use_debanding"] = "#define USE_DEBANDING\n";
 
 		actions.sampler_array_name = "material_samplers";
 		actions.base_texture_binding_index = 1;
diff --git a/servers/rendering/renderer_rd/shaders/environment/sky.glsl b/servers/rendering/renderer_rd/shaders/environment/sky.glsl
index 0eb0f5f8fd..d523461600 100644
--- a/servers/rendering/renderer_rd/shaders/environment/sky.glsl
+++ b/servers/rendering/renderer_rd/shaders/environment/sky.glsl
@@ -153,6 +153,15 @@ layout(set = 3, binding = 0) uniform texture3D volumetric_fog_texture;
 
 layout(location = 0) out vec4 frag_color;
 
+#ifdef USE_DEBANDING
+// https://www.iryoku.com/next-generation-post-processing-in-call-of-duty-advanced-warfare
+vec3 interleaved_gradient_noise(vec2 pos) {
+	const vec3 magic = vec3(0.06711056f, 0.00583715f, 52.9829189f);
+	float res = fract(magic.z * fract(dot(pos, magic.xy))) * 2.0 - 1.0;
+	return vec3(res, -res, res) / 255.0;
+}
+#endif
+
 vec4 volumetric_fog_process(vec2 screen_uv) {
 	vec3 fog_pos = vec3(screen_uv, 1.0);
 
@@ -252,4 +261,8 @@ void main() {
 	// For mobile renderer we're multiplying by 0.5 as we're using a UNORM buffer.
 	// For both mobile and clustered, we also bake in the exposure value for the environment and camera.
 	frag_color.rgb = frag_color.rgb * params.luminance_multiplier;
+
+#ifdef USE_DEBANDING
+	frag_color.rgb += interleaved_gradient_noise(gl_FragCoord.xy);
+#endif
 }
diff --git a/servers/rendering/shader_types.cpp b/servers/rendering/shader_types.cpp
index 43c483a00d..47cb38f268 100644
--- a/servers/rendering/shader_types.cpp
+++ b/servers/rendering/shader_types.cpp
@@ -444,6 +444,7 @@ ShaderTypes::ShaderTypes() {
 		shader_modes[RS::SHADER_SKY].modes.push_back({ PNAME("use_half_res_pass") });
 		shader_modes[RS::SHADER_SKY].modes.push_back({ PNAME("use_quarter_res_pass") });
 		shader_modes[RS::SHADER_SKY].modes.push_back({ PNAME("disable_fog") });
+		shader_modes[RS::SHADER_SKY].modes.push_back({ PNAME("use_debanding") });
 	}
 
 	/************ FOG **************************/