Optimize fog

Now it gets me as much FPS as no fog! (370 fps; prior to this commit
fog reduced it to 230)

2 files changed, 12 insertions, 16 deletions

diff --git a/src/main/resources/shaders/chunk.vert b/src/main/resources/shaders/chunk.vert
index 9901ef3..75ee0ab 100644
--- a/src/main/resources/shaders/chunk.vert
+++ b/src/main/resources/shaders/chunk.vert
@@ -20,6 +20,7 @@ out vec4 Viewport;
 out mat4 ProjInv;
 out vec4 FogColor;
 out vec2 FogStartEnd;
+out float FogFactor;
 
 void main()
 {
@@ -30,5 +31,14 @@ void main()
 	Viewport = viewport;
 	ProjInv = projInv;
 	FogColor = fogColor;
+	
+	float s = fogStartEnd.x;
+	float e = fogStartEnd.y;
+	vec4 eyePos = (modelView * (vec4(aPos - playerPos, 1.0) + vec4(0, 0.12, 0, 0)));
+	
+	float fogFactor = clamp((e - length(eyePos)) / (e - s), 0, 1);
+	
+	FogFactor = fogFactor;
+	
 	FogStartEnd = fogStartEnd;
 }
\ No newline at end of file
diff --git a/src/main/resources/shaders/chunk_fog.frag b/src/main/resources/shaders/chunk_fog.frag
index 36c10af..160ae65 100644
--- a/src/main/resources/shaders/chunk_fog.frag
+++ b/src/main/resources/shaders/chunk_fog.frag
@@ -8,6 +8,7 @@ in vec4 Viewport;
 in mat4 ProjInv;
 in vec4 FogColor;
 in vec2 FogStartEnd;
+in float FogFactor;
 
 uniform sampler2D atlas;
 uniform sampler2D lightTex;
@@ -21,20 +22,5 @@ void main()
 	
 	vec4 rasterColor = ((texColor * colorMult) * lightyColor);
 	
-	float s = FogStartEnd.x;
-	float e = FogStartEnd.y;
-	
-	vec4 ndcPos;
-	ndcPos.xy = ((2.0 * gl_FragCoord.xy) - (2.0 * Viewport.xy)) / (Viewport.zw) - 1;
-	ndcPos.z = (2.0 * gl_FragCoord.z - gl_DepthRange.near - gl_DepthRange.far) /
-		(gl_DepthRange.far - gl_DepthRange.near);
-	ndcPos.w = 1.0;
-
-	vec4 clipPos = ndcPos / gl_FragCoord.w;
-	vec4 eyePos = ProjInv * clipPos;
-	
-	float z = length(eyePos);
-	float f = (e - z) / (e - s);
-	f = clamp(f, 0, 1);
-	FragColor = mix(FogColor, rasterColor, f);
+	FragColor = vec4(mix(FogColor.xyz, rasterColor.xyz, FogFactor), rasterColor.w);
 }