Add dynamic exposure correction (#12959)

* Add uniform for frame delta time
* Adjust exposure in logarithmic (EV) space
* Add network support and LUA API
* Add testing mod

2 files changed, 15 insertions, 6 deletions

diff --git a/client/shaders/extract_bloom/opengl_fragment.glsl b/client/shaders/extract_bloom/opengl_fragment.glsl
index af320f9ab..45f5e9c6f 100644
--- a/client/shaders/extract_bloom/opengl_fragment.glsl
+++ b/client/shaders/extract_bloom/opengl_fragment.glsl
@@ -1,8 +1,12 @@
 #define rendered texture0
 
+struct ExposureParams {
+	float compensationFactor;
+};
+
 uniform sampler2D rendered;
-uniform mediump float exposureFactor;
 uniform mediump float bloomStrength;
+uniform ExposureParams exposureParams;
 
 #ifdef GL_ES
 varying mediump vec2 varTexCoord;
@@ -10,6 +14,7 @@ varying mediump vec2 varTexCoord;
 centroid varying vec2 varTexCoord;
 #endif
 
+varying float exposure;
 
 void main(void)
 {
@@ -18,10 +23,6 @@ void main(void)
 	// translate to linear colorspace (approximate)
 	color = pow(color, vec3(2.2));
 
-	// Scale colors by luminance to amplify bright colors
-	// in SDR textures.
-	float luminance = dot(color, vec3(0.213, 0.515, 0.072));
-	luminance *= luminance;
-	color *= luminance * exposureFactor * bloomStrength;
+	color *= pow(2., exposure) * exposureParams.compensationFactor * bloomStrength;
 	gl_FragColor = vec4(color, 1.0); // force full alpha to avoid holes in the image.
 }
diff --git a/client/shaders/extract_bloom/opengl_vertex.glsl b/client/shaders/extract_bloom/opengl_vertex.glsl
index 12692c296..479ae1079 100644
--- a/client/shaders/extract_bloom/opengl_vertex.glsl
+++ b/client/shaders/extract_bloom/opengl_vertex.glsl
@@ -1,11 +1,19 @@
+#define exposureMap texture1
+
+uniform sampler2D exposureMap;
+
 #ifdef GL_ES
 varying mediump vec2 varTexCoord;
 #else
 centroid varying vec2 varTexCoord;
 #endif
 
+varying float exposure;
+
 void main(void)
 {
+	exposure = texture2D(exposureMap, vec2(0.5)).r;
+
 	varTexCoord.st = inTexCoord0.st;
 	gl_Position = inVertexPosition;
 }