GPU: Avoid clears for non-simple depth values.

Some drivers don't round depth the same way for a clear vs for drawing,
which can cause mismatches.  We only do this if we see equals-style depth
comparison funcs used in drawing.

GPU/Common/DrawEngineCommon.h

@@ -145,11 +145,28 @@ protected:
 		return 1;
 	}
 
+	inline void UpdateEverUsedEqualDepth(GEComparison comp) {
+		switch (comp) {
+		case GE_COMP_EQUAL:
+		case GE_COMP_NOTEQUAL:
+		case GE_COMP_LEQUAL:
+		case GE_COMP_GEQUAL:
+			everUsedEqualDepth_ = true;
+			break;
+
+		default:
+			break;
+		}
+	}
+
 	bool useHWTransform_ = false;
 	bool useHWTessellation_ = false;
 	// Used to prevent unnecessary flushing in softgpu.
 	bool flushOnParams_ = true;
 
+	// Set once a equal depth test is encountered.
+	bool everUsedEqualDepth_ = false;
+
 	// Vertex collector buffers
 	u8 *decoded = nullptr;
 	u16 *decIndex = nullptr;

GPU/D3D11/DrawEngineD3D11.cpp

@@ -643,6 +643,10 @@ rotateVBO:
 			swTransform.BuildDrawingParams(prim, indexGen.VertexCount(), dec_->VertexType(), inds, maxIndex, &result);
 		if (result.setSafeSize)
 			framebufferManager_->SetSafeSize(result.safeWidth, result.safeHeight);
+		// Non-zero depth clears are unusual, but some drivers don't match drawn depth values to cleared values.
+		// Games sometimes expect exact matches (see #12626, for example) for equal comparisons.
+		if (result.action == SW_CLEAR && everUsedEqualDepth_ && gstate.isClearModeDepthMask() && result.depth > 0.0f && result.depth < 1.0f)
+			result.action = SW_DRAW_PRIMITIVES;
 
 		ApplyDrawStateLate(result.setStencil, result.stencilValue);
 

GPU/D3D11/StateMappingD3D11.cpp

@@ -274,6 +274,7 @@ void DrawEngineD3D11::ApplyDrawState(int prim) {
 				keys_.depthStencil.depthTestEnable = true;
 				keys_.depthStencil.depthCompareOp = compareOps[gstate.getDepthTestFunction()];
 				keys_.depthStencil.depthWriteEnable = gstate.isDepthWriteEnabled();
+				UpdateEverUsedEqualDepth(gstate.getDepthTestFunction());
 			} else {
 				keys_.depthStencil.depthTestEnable = false;
 				keys_.depthStencil.depthWriteEnable = false;

GPU/Directx9/DrawEngineDX9.cpp

@@ -611,6 +611,10 @@ rotateVBO:
 			swTransform.BuildDrawingParams(prim, indexGen.VertexCount(), dec_->VertexType(), inds, maxIndex, &result);
 		if (result.setSafeSize)
 			framebufferManager_->SetSafeSize(result.safeWidth, result.safeHeight);
+		// Non-zero depth clears are unusual, but some drivers don't match drawn depth values to cleared values.
+		// Games sometimes expect exact matches (see #12626, for example) for equal comparisons.
+		if (result.action == SW_CLEAR && everUsedEqualDepth_ && gstate.isClearModeDepthMask() && result.depth > 0.0f && result.depth < 1.0f)
+			result.action = SW_DRAW_PRIMITIVES;
 
 		ApplyDrawStateLate();
 

GPU/Directx9/StateMappingDX9.cpp

@@ -232,6 +232,7 @@ void DrawEngineDX9::ApplyDrawState(int prim) {
 				dxstate.depthTest.enable();
 				dxstate.depthFunc.set(ztests[gstate.getDepthTestFunction()]);
 				dxstate.depthWrite.set(gstate.isDepthWriteEnabled());
+				UpdateEverUsedEqualDepth(gstate.getDepthTestFunction());
 			} else {
 				dxstate.depthTest.disable();
 			}

GPU/GLES/DrawEngineGLES.cpp

@@ -404,6 +404,10 @@ void DrawEngineGLES::DoFlush() {
 			swTransform.BuildDrawingParams(prim, vertexCount, dec_->VertexType(), inds, maxIndex, &result);
 		if (result.setSafeSize)
 			framebufferManager_->SetSafeSize(result.safeWidth, result.safeHeight);
+		// Non-zero depth clears are unusual, but some drivers don't match drawn depth values to cleared values.
+		// Games sometimes expect exact matches (see #12626, for example) for equal comparisons.
+		if (result.action == SW_CLEAR && everUsedEqualDepth_ && gstate.isClearModeDepthMask() && result.depth > 0.0f && result.depth < 1.0f)
+			result.action = SW_DRAW_PRIMITIVES;
 
 		ApplyDrawStateLate(result.setStencil, result.stencilValue);
 

GPU/GLES/StateMappingGLES.cpp

@@ -254,6 +254,8 @@ void DrawEngineGLES::ApplyDrawState(int prim) {
 		} else {
 			// Depth Test
 			renderManager->SetDepth(gstate.isDepthTestEnabled(), gstate.isDepthWriteEnabled(), compareOps[gstate.getDepthTestFunction()]);
+			if (gstate.isDepthTestEnabled())
+				UpdateEverUsedEqualDepth(gstate.getDepthTestFunction());
 
 			// Stencil Test
 			if (stencilState.enabled) {

GPU/Vulkan/DrawEngineVulkan.cpp

@@ -899,6 +899,10 @@ void DrawEngineVulkan::DoFlush() {
 
 		if (result.setSafeSize)
 			framebufferManager_->SetSafeSize(result.safeWidth, result.safeHeight);
+		// Non-zero depth clears are unusual, but some drivers don't match drawn depth values to cleared values.
+		// Games sometimes expect exact matches (see #12626, for example) for equal comparisons.
+		if (result.action == SW_CLEAR && everUsedEqualDepth_ && gstate.isClearModeDepthMask() && result.depth > 0.0f && result.depth < 1.0f)
+			result.action = SW_DRAW_PRIMITIVES;
 
 		// Only here, where we know whether to clear or to draw primitives, should we actually set the current framebuffer! Because that gives use the opportunity
 		// to use a "pre-clear" render pass, for high efficiency on tilers.

GPU/Vulkan/StateMappingVulkan.cpp

@@ -278,6 +278,7 @@ void DrawEngineVulkan::ConvertStateToVulkanKey(FramebufferManagerVulkan &fbManag
 				key.depthTestEnable = true;
 				key.depthCompareOp = compareOps[gstate.getDepthTestFunction()];
 				key.depthWriteEnable = gstate.isDepthWriteEnabled();
+				UpdateEverUsedEqualDepth(gstate.getDepthTestFunction());
 			} else {
 				key.depthTestEnable = false;
 				key.depthWriteEnable = false;