Added tessellation evaluation shader frustum culling and pipeline stats for dynamic terrain tessellation example

data/shaders/terraintessellation/terrain.frag

@@ -54,4 +54,6 @@ void main()
 	outFragColor = vec4((IAmbient + IDiffuse) * vec4(texture(terrainLayers, vec3(inUV, 0.0)).rgb, 1.0));	
 */
 	outFragColor = sampleTerrainLayer();
-}
+
+	//outFragColor.rgb = normalize(inNormal);
+}

data/shaders/terraintessellation/terrain.tesc

@@ -8,13 +8,14 @@ layout(set = 0, binding = 0) uniform UBO
 	mat4 projection;
 	mat4 modelview;
 	vec4 lightPos;
+	vec4 frustumPlanes[6];
 	float displacementFactor;
 	float tessellationFactor;
 	vec2 viewportDim;
 	float tessellatedEdgeSize;
 } ubo;
 
-layout(set = 0, binding = 2) uniform sampler2D samplerHeight;
+layout(set = 0, binding = 1) uniform sampler2D samplerHeight;
 
 layout (vertices = 4) out;
  
@@ -31,7 +32,7 @@ float screenSpaceTessFactor(vec4 p0, vec4 p1)
 	// Calculate edge mid point
 	vec4 midPoint = 0.5 * (p0 + p1);
 	// Sphere radius as distance between the control points
-	float radius = distance(p0, p1) / 2;
+	float radius = distance(p0, p1) / 2.0;
 
 	// View space
 	vec4 v0 = ubo.modelview  * midPoint;
@@ -54,30 +55,62 @@ float screenSpaceTessFactor(vec4 p0, vec4 p1)
 	return clamp(distance(clip0, clip1) / ubo.tessellatedEdgeSize * ubo.tessellationFactor, 1.0, 64.0);
 }
 
+// Checks the current's patch visibility against the frustum using a sphere check
+// Sphere radius is given by the patch size
+bool frustumCheck()
+{
+	// Fixed radius (increase if patch size is increased in example)
+	const float radius = 8.0f;
+	vec4 pos = gl_in[gl_InvocationID].gl_Position;
+	pos.y -= textureLod(samplerHeight, inUV[0], 0.0).r * ubo.displacementFactor;
+
+	// Check sphere against frustum planes
+	for (int i = 0; i < 6; i++) {
+		if (dot(pos, ubo.frustumPlanes[i]) + radius < 0.0)
+		{
+			return false;
+		}
+	}
+	return true;
+}
+
 void main()
 {
 	if (gl_InvocationID == 0)
 	{
-		if (ubo.tessellationFactor > 0.0)
+		if (!frustumCheck())
 		{
-			gl_TessLevelOuter[0] = screenSpaceTessFactor(gl_in[3].gl_Position, gl_in[0].gl_Position);
-			gl_TessLevelOuter[1] = screenSpaceTessFactor(gl_in[0].gl_Position, gl_in[1].gl_Position);
-			gl_TessLevelOuter[2] = screenSpaceTessFactor(gl_in[1].gl_Position, gl_in[2].gl_Position);
-			gl_TessLevelOuter[3] = screenSpaceTessFactor(gl_in[2].gl_Position, gl_in[3].gl_Position);
-			gl_TessLevelInner[0] = mix(gl_TessLevelOuter[0], gl_TessLevelOuter[3], 0.5);
-			gl_TessLevelInner[1] = mix(gl_TessLevelOuter[2], gl_TessLevelOuter[1], 0.5);
+			gl_TessLevelInner[0] = 0.0;
+			gl_TessLevelInner[1] = 0.0;
+			gl_TessLevelOuter[0] = 0.0;
+			gl_TessLevelOuter[1] = 0.0;
+			gl_TessLevelOuter[2] = 0.0;
+			gl_TessLevelOuter[3] = 0.0;
 		}
 		else
 		{
-			// Tessellation factor can be set to zero by example
-			// to demonstrate a simple passthrough
-			gl_TessLevelInner[0] = 1.0;
-			gl_TessLevelInner[1] = 1.0;
-			gl_TessLevelOuter[0] = 1.0;
-			gl_TessLevelOuter[1] = 1.0;
-			gl_TessLevelOuter[2] = 1.0;
-			gl_TessLevelOuter[3] = 1.0;
+			if (ubo.tessellationFactor > 0.0)
+			{
+				gl_TessLevelOuter[0] = screenSpaceTessFactor(gl_in[3].gl_Position, gl_in[0].gl_Position);
+				gl_TessLevelOuter[1] = screenSpaceTessFactor(gl_in[0].gl_Position, gl_in[1].gl_Position);
+				gl_TessLevelOuter[2] = screenSpaceTessFactor(gl_in[1].gl_Position, gl_in[2].gl_Position);
+				gl_TessLevelOuter[3] = screenSpaceTessFactor(gl_in[2].gl_Position, gl_in[3].gl_Position);
+				gl_TessLevelInner[0] = mix(gl_TessLevelOuter[0], gl_TessLevelOuter[3], 0.5);
+				gl_TessLevelInner[1] = mix(gl_TessLevelOuter[2], gl_TessLevelOuter[1], 0.5);
+			}
+			else
+			{
+				// Tessellation factor can be set to zero by example
+				// to demonstrate a simple passthrough
+				gl_TessLevelInner[0] = 1.0;
+				gl_TessLevelInner[1] = 1.0;
+				gl_TessLevelOuter[0] = 1.0;
+				gl_TessLevelOuter[1] = 1.0;
+				gl_TessLevelOuter[2] = 1.0;
+				gl_TessLevelOuter[3] = 1.0;
+			}
 		}
+
 	}
 
 	gl_out[gl_InvocationID].gl_Position =  gl_in[gl_InvocationID].gl_Position;

data/shaders/terraintessellation/terrain.tese

@@ -8,8 +8,11 @@ layout (set = 0, binding = 0) uniform UBO
 	mat4 projection;
 	mat4 modelview;
 	vec4 lightPos;
+	vec4 frustumPlanes[6];
 	float displacementFactor;
-	float tessellationFalloff;
+	float tessellationFactor;
+	vec2 viewportDim;
+	float tessellatedEdgeSize;
 } ubo; 
 
 layout (set = 0, binding = 1) uniform sampler2D displacementMap;