Move Fog matrix inversion to the CPU

core/src/main/java/com/seibel/distanthorizons/core/render/renderer/shaders/FogShader.java

@@ -21,7 +21,7 @@ public class FogShader extends AbstractShaderRenderer
 	private static final IVersionConstants VERSION_CONSTANTS = SingletonInjector.INSTANCE.get(IVersionConstants.class);
 	
 	
-	public final int gModelViewProjectionUniform;
+	public final int gInvertedModelViewProjectionUniform;
 	public final int gDepthMapUniform;
 	
 	// Fog Uniforms
@@ -48,7 +48,7 @@ public class FogShader extends AbstractShaderRenderer
 		// because disabling fog can cause the GLSL to optimize out most (if not all) uniforms
 		
 		
-		this.gModelViewProjectionUniform = this.shader.tryGetUniformLocation("gMvmProj");
+		this.gInvertedModelViewProjectionUniform = this.shader.tryGetUniformLocation("gInvMvmProj");
 		this.gDepthMapUniform = this.shader.tryGetUniformLocation("gDepthMap");
 		
 		// Fog uniforms
@@ -119,7 +119,11 @@ public class FogShader extends AbstractShaderRenderer
 	public void setModelViewProjectionMatrix(Mat4f combinedModelViewProjectionMatrix)
 	{
 		this.shader.bind();
-		this.shader.setUniform(this.gModelViewProjectionUniform, combinedModelViewProjectionMatrix);
+		
+		Mat4f inverseMvmProjMatrix = new Mat4f(combinedModelViewProjectionMatrix);
+		inverseMvmProjMatrix.invert();
+		this.shader.setUniform(this.gInvertedModelViewProjectionUniform, inverseMvmProjMatrix);
+		
 		this.shader.unbind();
 	}
 	

core/src/main/resources/shaders/fog/fog.frag

@@ -4,8 +4,8 @@ in vec2 TexCoord;
 out vec4 fragColor;
 
 uniform sampler2D gDepthMap;
-// model view matrix and projection matrix
-uniform mat4 gMvmProj;
+// inverted model view matrix and projection matrix
+uniform mat4 gInvMvmProj;
 
 uniform float fogScale;
 uniform float fogVerticalScale;
@@ -62,8 +62,7 @@ vec3 calcViewPosition(float fragmentDepth)
     vec4 ndc = vec4(TexCoord.xy, fragmentDepth, 1.0);
     ndc.xyz = ndc.xyz * 2.0 - 1.0;
 
-    // TODO: This inverse() should be moved CPU side
-    vec4 eyeCoord = inverse(gMvmProj) * ndc;
+    vec4 eyeCoord = gInvMvmProj * ndc;
     return eyeCoord.xyz / eyeCoord.w;
 }