Add detection/support for reverse-z projection matrices. Refs #169

renderdoc/driver/d3d11/d3d11_debug.cpp

@@ -4118,6 +4118,8 @@ void D3D11DebugManager::InitPostVSBuffers(uint32_t frameID, uint32_t eventID)
 
 		Vec4f *pos0 = (Vec4f *)byteData;
 
+		bool found = false;
+
 		for(UINT64 i=1; numPosComponents == 4 && i < numPrims.NumPrimitivesWritten; i++)
 		{
 			//////////////////////////////////////////////////////////////////////////////////
@@ -4140,7 +4142,7 @@ void D3D11DebugManager::InitPostVSBuffers(uint32_t frameID, uint32_t eventID)
 
 			Vec4f *pos = (Vec4f *)(byteData + i*stride);
 
-			if(fabs(pos->w - pos0->w) > 0.01f)
+			if(fabs(pos->w - pos0->w) > 0.01f && fabs(pos->z - pos0->z) > 0.01f)
 			{
 				Vec2f A(pos0->w, pos0->z);
 				Vec2f B(pos->w, pos->z);
@@ -4153,10 +4155,21 @@ void D3D11DebugManager::InitPostVSBuffers(uint32_t frameID, uint32_t eventID)
 				nearp = -c/m;
 				farp = c/(1-m);
 
+				found = true;
+
 				break;
 			}
 		}
 
+		// if we didn't find anything, all z's and w's were identical.
+		// If the z is positive and w greater for the first element then
+		// we detect this projection as reversed z with infinite far plane
+		if(!found && pos0->z > 0.0f && pos0->w > pos0->z)
+		{
+			nearp = pos0->z;
+			farp = FLT_MAX;
+		}
+
 		m_pImmediateContext->Unmap(m_SOStagingBuffer, 0);
 
 		m_PostVSData[idx].vsin.topo = topo;
@@ -4698,7 +4711,9 @@ void D3D11DebugManager::RenderMesh(uint32_t frameID, uint32_t eventID, const vec
 		{
 			// the derivation of the projection matrix might not be right (hell, it could be an
 			// orthographic projection). But it'll be close enough likely.
-			Matrix4f guessProj = Matrix4f::Perspective(cfg.fov, cfg.position.nearPlane, cfg.position.farPlane, cfg.aspect);
+			Matrix4f guessProj = cfg.position.farPlane != FLT_MAX
+				? Matrix4f::Perspective(cfg.fov, cfg.position.nearPlane, cfg.position.farPlane, cfg.aspect)
+				: Matrix4f::ReversePerspective(cfg.fov, cfg.position.nearPlane, cfg.aspect);
 
 			if(cfg.ortho)
 			{

renderdoc/driver/gl/gl_debug.cpp

@@ -2795,6 +2795,8 @@ void GLReplay::InitPostVSBuffers(uint32_t frameID, uint32_t eventID)
 
 	Vec4f *pos0 = (Vec4f *)byteData;
 
+	bool found = false;
+
 	for(GLuint i=1; posidx != -1 && i < primsWritten; i++)
 	{
 		//////////////////////////////////////////////////////////////////////////////////
@@ -2817,7 +2819,7 @@ void GLReplay::InitPostVSBuffers(uint32_t frameID, uint32_t eventID)
 
 		Vec4f *pos = (Vec4f *)(byteData + i*stride);
 
-		if(fabs(pos->w - pos0->w) > 0.01f)
+		if(fabs(pos->w - pos0->w) > 0.01f && fabs(pos->z - pos0->z) > 0.01f)
 		{
 			Vec2f A(pos0->w, pos0->z);
 			Vec2f B(pos->w, pos->z);
@@ -2829,11 +2831,22 @@ void GLReplay::InitPostVSBuffers(uint32_t frameID, uint32_t eventID)
 
 			nearp = -c/m;
 			farp = c/(1-m);
+			
+			found = true;
 
 			break;
 		}
 	}
 
+	// if we didn't find anything, all z's and w's were identical.
+	// If the z is positive and w greater for the first element then
+	// we detect this projection as reversed z with infinite far plane
+	if(!found && pos0->z > 0.0f && pos0->w > pos0->z)
+	{
+		nearp = pos0->z;
+		farp = FLT_MAX;
+	}
+
 	gl.glUnmapNamedBufferEXT(DebugData.feedbackBuffer);
 
 	// store everything out to the PostVS data cache
@@ -3426,7 +3439,9 @@ void GLReplay::RenderMesh(uint32_t frameID, uint32_t eventID, const vector<MeshF
 	{
 		// the derivation of the projection matrix might not be right (hell, it could be an
 		// orthographic projection). But it'll be close enough likely.
-		Matrix4f guessProj = Matrix4f::Perspective(cfg.fov, cfg.position.nearPlane, cfg.position.farPlane, cfg.aspect);
+		Matrix4f guessProj = cfg.position.farPlane != FLT_MAX
+			? Matrix4f::Perspective(cfg.fov, cfg.position.nearPlane, cfg.position.farPlane, cfg.aspect)
+			: Matrix4f::ReversePerspective(cfg.fov, cfg.position.nearPlane, cfg.aspect);
 
 		if(cfg.ortho)
 		{

renderdoc/maths/matrix.cpp

@@ -391,3 +391,17 @@ Matrix4f Matrix4f::Perspective(const float degfov, const float N, const float F,
 	
 	return Matrix4f(persp);
 }
+
+Matrix4f Matrix4f::ReversePerspective(const float degfov, const float N, const float A)
+{
+	const float radfov = degfov * (3.1415926535f/180.0f);
+	float S = 1/tanf(radfov * 0.5f);
+	
+	float persp[16] = { S/A, 0.0f, 0.0f, 0.0f,
+						0.0f, S, 0.0f, 0.0f,
+						0.0f, 0.0f, 0.0f, 1.0f,
+						0.0f, 0.0f, N, 0.0f,
+						};
+	
+	return Matrix4f(persp);
+}

renderdoc/maths/matrix.h

@@ -60,6 +60,7 @@ class Matrix4f
 		static Matrix4f RotationZYX(const Vec3f &rot);
 		static Matrix4f Orthographic(const float nearplane, const float farplane);
 		static Matrix4f Perspective(const float degfov, const float nearplane, const float farplane, const float aspect);
+		static Matrix4f ReversePerspective(const float degfov, const float nearplane, const float aspect);
 
 		inline float operator[](const size_t i) const
 		{