Merge pull request #113956 from allenwp/colour/remove-LinearToSRGB-clamping

Remove clamping from LinearToSRGB visual shader node.

doc/classes/VisualShaderNodeColorFunc.xml

@@ -43,11 +43,10 @@
 		<constant name="FUNC_LINEAR_TO_SRGB" value="4" enum="Function">
 			Converts color from linear encoding to nonlinear sRGB encoding using the following formula:
 			[codeblock]
-			vec3 c = clamp(c, vec3(0.0), vec3(1.0));
 			const vec3 a = vec3(0.055f);
 			return mix((vec3(1.0f) + a) * pow(c.rgb, vec3(1.0f / 2.4f)) - a, 12.92f * c.rgb, lessThan(c.rgb, vec3(0.0031308f)));
 			[/codeblock]
-			The Compatibility renderer uses a simpler formula:
+			The Compatibility renderer uses a simpler formula that may produce undefined behavior with negative input values:
 			[codeblock]
 			vec3 c = input;
 			return max(vec3(1.055) * pow(c, vec3(0.416666667)) - vec3(0.055), vec3(0.0));
@@ -59,7 +58,7 @@
 			vec3 c = input;
 			return mix(pow((c.rgb + vec3(0.055)) * (1.0 / (1.0 + 0.055)), vec3(2.4)), c.rgb * (1.0 / 12.92), lessThan(c.rgb, vec3(0.04045)));
 			[/codeblock]
-			The Compatibility renderer uses a simpler formula:
+			The Compatibility renderer uses a simpler formula that behaves poorly with negative input values:
 			[codeblock]
 			vec3 c = input;
 			return c * (c * (c * 0.305306011 + 0.682171111) + 0.012522878);

drivers/gles3/shaders/effects/copy.glsl

@@ -106,13 +106,13 @@ uniform float aspect_ratio;
 
 layout(location = 0) out vec4 frag_color;
 
-// This expects 0-1 range input, outside that range it behaves poorly.
+// This approximation expects non-negative input; negative input behaves poorly.
 vec3 srgb_to_linear(vec3 color) {
 	// Approximation from http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
 	return color * (color * (color * 0.305306011 + 0.682171111) + 0.012522878);
 }
 
-// This expects 0-1 range input.
+// This approximation expects non-negative input; negative input is undefined behavior.
 vec3 linear_to_srgb(vec3 color) {
 	// Approximation from http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
 	return max(vec3(1.055) * pow(color, vec3(0.416666667)) - vec3(0.055), vec3(0.0));

drivers/gles3/shaders/effects/cubemap_filter.glsl

@@ -43,10 +43,12 @@ layout(location = 0) out vec4 frag_color;
 #define M_PI 3.14159265359
 
 // Don't include tonemap_inc.glsl because all we want is these functions, we don't want the uniforms
+// This approximation expects non-negative input; negative input is undefined behavior.
 vec3 linear_to_srgb(vec3 color) {
 	return max(vec3(1.055) * pow(color, vec3(0.416666667)) - vec3(0.055), vec3(0.0));
 }
 
+// This approximation expects non-negative input; negative input behaves poorly.
 vec3 srgb_to_linear(vec3 color) {
 	return color * (color * (color * 0.305306011 + 0.682171111) + 0.012522878);
 }

drivers/gles3/shaders/tonemap_inc.glsl

@@ -10,16 +10,15 @@ layout(std140) uniform TonemapData { //ubo:0
 	int pad3;
 };
 
-// This expects 0-1 range input.
+// This approximation expects non-negative input; negative input is undefined behavior.
 vec3 linear_to_srgb(vec3 color) {
-	//color = clamp(color, vec3(0.0), vec3(1.0));
 	//const vec3 a = vec3(0.055f);
 	//return mix((vec3(1.0f) + a) * pow(color.rgb, vec3(1.0f / 2.4f)) - a, 12.92f * color.rgb, lessThan(color.rgb, vec3(0.0031308f)));
 	// Approximation from http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
 	return max(vec3(1.055) * pow(color, vec3(0.416666667)) - vec3(0.055), vec3(0.0));
 }
 
-// This expects 0-1 range input, outside that range it behaves poorly.
+// This approximation expects non-negative input; negative input behaves poorly.
 vec3 srgb_to_linear(vec3 color) {
 	// Approximation from http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
 	return color * (color * (color * 0.305306011 + 0.682171111) + 0.012522878);

scene/resources/visual_shader_nodes.cpp

@@ -3263,7 +3263,7 @@ String VisualShaderNodeColorFunc::generate_code(Shader::Mode p_mode, VisualShade
 				code += "		vec3 c = " + p_input_vars[0] + ";\n";
 				code += "		" + p_output_vars[0] + " = max(vec3(1.055) * pow(c, vec3(0.416666667)) - vec3(0.055), vec3(0.0));\n";
 			} else {
-				code += "		vec3 c = clamp(" + p_input_vars[0] + ", vec3(0.0), vec3(1.0));\n";
+				code += "		vec3 c = " + p_input_vars[0] + ";\n";
 				code += "		const vec3 a = vec3(0.055f);\n";
 				code += "		" + p_output_vars[0] + " = mix((vec3(1.0f) + a) * pow(c.rgb, vec3(1.0f / 2.4f)) - a, 12.92f * c.rgb, lessThan(c.rgb, vec3(0.0031308f)));\n";
 			}

servers/rendering/renderer_rd/shaders/effects/copy_to_fb.glsl

@@ -106,8 +106,6 @@ layout(set = 1, binding = 0) uniform sampler2D source_color2;
 layout(location = 0) out vec4 frag_color;
 
 vec3 linear_to_srgb(vec3 color) {
-	//if going to srgb, clamp from 0 to 1.
-	color = clamp(color, vec3(0.0), vec3(1.0));
 	const vec3 a = vec3(0.055f);
 	return mix((vec3(1.0f) + a) * pow(color.rgb, vec3(1.0f / 2.4f)) - a, 12.92f * color.rgb, lessThan(color.rgb, vec3(0.0031308f)));
 }
@@ -179,6 +177,7 @@ void main() {
 	}
 	if (bool(params.flags & FLAG_SRGB)) {
 		color.rgb = linear_to_srgb(color.rgb);
+		color.rgb = clamp(color.rgb, vec3(0.0), vec3(1.0));
 	}
 	if (bool(params.flags & FLAG_ALPHA_TO_ONE)) {
 		color.a = 1.0;

servers/rendering/renderer_rd/shaders/environment/sdfgi_debug.glsl

@@ -50,8 +50,6 @@ layout(push_constant, std430) uniform Params {
 params;
 
 vec3 linear_to_srgb(vec3 color) {
-	//if going to srgb, clamp from 0 to 1.
-	color = clamp(color, vec3(0.0), vec3(1.0));
 	const vec3 a = vec3(0.055f);
 	return mix((vec3(1.0f) + a) * pow(color.rgb, vec3(1.0f / 2.4f)) - a, 12.92f * color.rgb, lessThan(color.rgb, vec3(0.0031308f)));
 }
@@ -181,5 +179,5 @@ void main() {
 
 #endif
 
-	imageStore(screen_buffer, screen_pos, vec4(linear_to_srgb(light), 1.0));
+	imageStore(screen_buffer, screen_pos, vec4(clamp(linear_to_srgb(light), vec3(0.0), vec3(1.0)), 1.0));
 }