Started work on MSAA with deferred rendering example

data/shaders/deferredmultisampling/debug.frag

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+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (binding = 1) uniform sampler2DMS samplerPosition;
+layout (binding = 2) uniform sampler2DMS samplerNormal;
+layout (binding = 3) uniform sampler2DMS samplerAlbedo;
+
+layout (location = 0) in vec3 inUV;
+
+layout (location = 0) out vec4 outFragColor;
+
+#define NUM_SAMPLES 8
+
+vec4 resolve(sampler2DMS tex, ivec2 uv)
+{
+	vec4 result = vec4(0.0);	   
+	int count = 0;
+	for (int i = 0; i < NUM_SAMPLES; i++)
+	{
+		vec4 val = texelFetch(tex, uv, i); 
+		result += val;
+		count++;
+	}    
+	return result / float(NUM_SAMPLES);
+}
+
+void main() 
+{
+	ivec2 attDim = textureSize(samplerPosition);
+	ivec2 UV = ivec2(inUV.st * attDim * 2.0);
+
+	highp int index = 0;
+	if (inUV.s > 0.5)
+	{
+		index = 1;
+		UV.s -= attDim.x;
+	}
+	if (inUV.t > 0.5)
+	{
+		index = 2;
+		UV.t -= attDim.y;
+	}
+
+	vec3 components[3];
+	components[0] = resolve(samplerPosition, UV).rgb;  
+	components[1] = resolve(samplerNormal, UV).rgb;  
+	components[2] = resolve(samplerAlbedo, UV).rgb;  
+	// Uncomment to display specular component
+	//components[2] = vec3(texture(samplerAlbedo, inUV.st).a);  
+	
+	// Select component depending on UV
+	outFragColor.rgb = components[index];
+}

data/shaders/deferredmultisampling/debug.vert

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+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (binding = 0) uniform UBO 
+{
+	mat4 projection;
+	mat4 model;
+} ubo;
+
+layout (location = 0) out vec3 outUV;
+
+out gl_PerVertex
+{
+	vec4 gl_Position;
+};
+
+void main() 
+{
+	outUV = vec3((gl_VertexIndex << 1) & 2, gl_VertexIndex & 2, 0.0);
+	gl_Position = vec4(outUV.st * 2.0f - 1.0f, 0.0f, 1.0f);
+}

data/shaders/deferredmultisampling/deferred.frag

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+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (binding = 1) uniform sampler2DMS samplerPosition;
+layout (binding = 2) uniform sampler2DMS samplerNormal;
+layout (binding = 3) uniform sampler2DMS samplerAlbedo;
+
+layout (location = 0) in vec2 inUV;
+
+layout (location = 0) out vec4 outFragcolor;
+
+struct Light {
+	vec4 position;
+	vec3 color;
+	float radius;
+};
+
+layout (binding = 4) uniform UBO 
+{
+	Light lights[6];
+	vec4 viewPos;
+	ivec2 windowSize;
+} ubo;
+
+layout (constant_id = 0) const int NUM_SAMPLES = 8;
+
+#define NUM_LIGHTS 6
+
+// Manual resolve for MSAA samples 
+vec4 resolve(sampler2DMS tex, ivec2 uv)
+{
+	vec4 result = vec4(0.0);	   
+	for (int i = 0; i < NUM_SAMPLES; i++)
+	{
+		vec4 val = texelFetch(tex, uv, i); 
+		result += val;
+	}    
+	// Average resolved samples
+	return result / float(NUM_SAMPLES);
+}
+
+vec3 calculateLighting(vec3 pos, vec3 normal, vec4 albedo)
+{
+	vec3 result = vec3(0.0);
+
+	for(int i = 0; i < NUM_LIGHTS; ++i)
+	{
+		// Vector to light
+		vec3 L = ubo.lights[i].position.xyz - pos;
+		// Distance from light to fragment position
+		float dist = length(L);
+
+		// Viewer to fragment
+		vec3 V = ubo.viewPos.xyz - pos;
+		V = normalize(V);
+		
+		// Light to fragment
+		L = normalize(L);
+
+		// Attenuation
+		float atten = ubo.lights[i].radius / (pow(dist, 2.0) + 1.0);
+
+		// Diffuse part
+		vec3 N = normalize(normal);
+		float NdotL = max(0.0, dot(N, L));
+		vec3 diff = ubo.lights[i].color * albedo.rgb * NdotL * atten;
+
+		// Specular part
+		vec3 R = reflect(-L, N);
+		float NdotR = max(0.0, dot(R, V));
+		vec3 spec = ubo.lights[i].color * albedo.a * pow(NdotR, 8.0) * atten;
+
+		result += diff + spec;	
+	}
+	return result;
+}
+
+void main() 
+{
+	ivec2 attDim = textureSize(samplerPosition);
+	ivec2 UV = ivec2(inUV * attDim);
+	
+	#define ambient 0.15
+
+	// Ambient part
+	vec4 alb = resolve(samplerAlbedo, UV);
+	vec3 fragColor = vec3(0.0);
+	
+	// Calualte lighting for every MSAA sample
+	for (int i = 0; i < NUM_SAMPLES; i++)
+	{ 
+		vec3 pos = texelFetch(samplerPosition, UV, i).rgb;
+		vec3 normal = texelFetch(samplerNormal, UV, i).rgb;
+		vec4 albedo = texelFetch(samplerAlbedo, UV, i);
+		fragColor += calculateLighting(pos, normal, albedo);
+	}
+
+	fragColor = (alb.rgb * ambient) + fragColor / float(NUM_SAMPLES);
+   
+	outFragcolor = vec4(fragColor, 1.0);	
+}

data/shaders/deferredmultisampling/deferred.vert

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+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (location = 0) in vec3 inPos;
+layout (location = 1) in vec2 inUV;
+
+layout (binding = 0) uniform UBO 
+{
+	mat4 projection;
+	mat4 model;
+} ubo;
+
+layout (location = 0) out vec2 outUV;
+
+out gl_PerVertex
+{
+	vec4 gl_Position;
+};
+
+void main() 
+{
+	outUV = vec2((gl_VertexIndex << 1) & 2, gl_VertexIndex & 2);
+	gl_Position = vec4(outUV * 2.0f - 1.0f, 0.0f, 1.0f);
+}

data/shaders/deferredmultisampling/mrt.frag

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+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (binding = 1) uniform sampler2D samplerColor;
+layout (binding = 2) uniform sampler2D samplerNormalMap;
+
+layout (location = 0) in vec3 inNormal;
+layout (location = 1) in vec2 inUV;
+layout (location = 2) in vec3 inColor;
+layout (location = 3) in vec3 inWorldPos;
+layout (location = 4) in vec3 inTangent;
+
+layout (location = 0) out vec4 outPosition;
+layout (location = 1) out vec4 outNormal;
+layout (location = 2) out vec4 outAlbedo;
+
+void main() 
+{
+	outPosition = vec4(inWorldPos, 1.0);
+
+	// Calculate normal in tangent space
+	vec3 N = normalize(inNormal);
+	N.y = -N.y;
+	vec3 T = normalize(inTangent);
+	vec3 B = cross(N, T);
+	mat3 TBN = mat3(T, B, N);
+	vec3 tnorm = TBN * normalize(texture(samplerNormalMap, inUV).xyz * 2.0 - vec3(1.0));
+	outNormal = vec4(tnorm, 1.0);
+
+	outAlbedo = texture(samplerColor, inUV);
+}

data/shaders/deferredmultisampling/mrt.vert

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+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (location = 0) in vec4 inPos;
+layout (location = 1) in vec2 inUV;
+layout (location = 2) in vec3 inColor;
+layout (location = 3) in vec3 inNormal;
+layout (location = 4) in vec3 inTangent;
+
+layout (binding = 0) uniform UBO 
+{
+	mat4 projection;
+	mat4 model;
+	mat4 view;
+	vec4 instancePos[3];
+} ubo;
+
+layout (location = 0) out vec3 outNormal;
+layout (location = 1) out vec2 outUV;
+layout (location = 2) out vec3 outColor;
+layout (location = 3) out vec3 outWorldPos;
+layout (location = 4) out vec3 outTangent;
+
+out gl_PerVertex
+{
+	vec4 gl_Position;
+};
+
+void main() 
+{
+	vec4 tmpPos = vec4(inPos.xyz, 1.0) + ubo.instancePos[gl_InstanceIndex];
+
+	gl_Position = ubo.projection * ubo.view * ubo.model * tmpPos;
+	
+	outUV = inUV;
+	outUV.t = 1.0 - outUV.t;
+
+	// Vertex position in world space
+	outWorldPos = vec3(ubo.model * tmpPos);
+	// GL to Vulkan coord space
+	outWorldPos.y = -outWorldPos.y;
+	
+	// Normal in world space
+	mat3 mNormal = transpose(inverse(mat3(ubo.model)));
+	outNormal = mNormal * normalize(inNormal);	
+	outTangent = mNormal * normalize(inTangent);
+	
+	// Currently just vertex color
+	outColor = inColor;
+}