Add a config setting to control depth quality.

For those who want 1x PSP like behavior.

Core/Config.cpp

@@ -442,6 +442,7 @@ static ConfigSetting graphicsSettings[] = {
 	ReportedConfigSetting("BufferFiltering", &g_Config.iBufFilter, 1, true, true),
 	ReportedConfigSetting("InternalResolution", &g_Config.iInternalResolution, &DefaultInternalResolution, true, true),
 	ReportedConfigSetting("AndroidHwScale", &g_Config.iAndroidHwScale, &DefaultAndroidHwScale),
+	ReportedConfigSetting("HighQualityDepth", &g_Config.bHighQualityDepth, true, true, true),
 	ReportedConfigSetting("FrameSkip", &g_Config.iFrameSkip, 0, true, true),
 	ReportedConfigSetting("AutoFrameSkip", &g_Config.bAutoFrameSkip, false, true, true),
 	ReportedConfigSetting("FrameRate", &g_Config.iFpsLimit, 0, true, true),

Core/Config.h

@@ -173,6 +173,7 @@ public:
 	bool bFullScreen;
 	int iInternalResolution;  // 0 = Auto (native), 1 = 1x (480x272), 2 = 2x, 3 = 3x, 4 = 4x and so on.
 	int iAnisotropyLevel;  // 0 - 5, powers of 2: 0 = 1x = no aniso
+	int bHighQualityDepth;
 	bool bTrueColor;
 	bool bMipMap;
 	int iTexScalingLevel; // 1 = off, 2 = 2x, ..., 5 = 5x

GPU/Common/GPUStateUtils.cpp

@@ -498,10 +498,19 @@ LogicOpReplaceType ReplaceLogicOpType() {
 	return LOGICOPTYPE_NORMAL;
 }
 
-static const float depthSliceFactor = 4.0f;
+static const float DEPTH_SLICE_FACTOR_HIGH = 4.0f;
+static const float DEPTH_SLICE_FACTOR_16BIT = 256.0f;
+
+float DepthSliceFactor() {
+	if (gstate_c.Supports(GPU_SCALE_DEPTH_FROM_24BIT_TO_16BIT)) {
+		return DEPTH_SLICE_FACTOR_16BIT;
+	}
+	return DEPTH_SLICE_FACTOR_HIGH;
+}
 
 // This is used for float values which might not be integers, but are in the integer scale of 65535.
 static float ToScaledDepthFromInteger(float z) {
+	const float depthSliceFactor = DepthSliceFactor();
 	const float offset = 0.5f * (depthSliceFactor - 1.0f) * (1.0f / depthSliceFactor);
 	return z * (1.0f / depthSliceFactor) * (1.0f / 65535.0f) + offset;
 }
@@ -511,14 +520,11 @@ float ToScaledDepth(u16 z) {
 }
 
 float FromScaledDepth(float z) {
+	const float depthSliceFactor = DepthSliceFactor();
 	const float offset = 0.5f * (depthSliceFactor - 1.0f) * (1.0f / depthSliceFactor);
 	return (z - offset) * depthSliceFactor * 65535.0f;
 }
 
-float DepthSliceFactor() {
-	return depthSliceFactor;
-}
-
 void ConvertViewportAndScissor(bool useBufferedRendering, float renderWidth, float renderHeight, int bufferWidth, int bufferHeight, ViewportAndScissor &out) {
 	bool throughmode = gstate.isModeThrough();
 	out.dirtyProj = false;
@@ -662,7 +668,7 @@ void ConvertViewportAndScissor(bool useBufferedRendering, float renderWidth, flo
 			// Here, we should "clamp."  But clamping per fragment would be slow.
 			// So, instead, we just increase the available range and hope.
 			// If depthSliceFactor is 4, it means (75% / 2) of the depth lies in each direction.
-			float fullDepthRange = 65535.0f * (depthSliceFactor - 1.0f) * (1.0f / 2.0f);
+			float fullDepthRange = 65535.0f * (DepthSliceFactor() - 1.0f) * (1.0f / 2.0f);
 			if (minz == 0) {
 				minz -= fullDepthRange;
 			}

GPU/Directx9/GPU_DX9.cpp

@@ -478,7 +478,9 @@ void DIRECTX9_GPU::CheckGPUFeatures() {
 	features |= GPU_SUPPORTS_TEXTURE_LOD_CONTROL;
 	features |= GPU_PREFER_CPU_DOWNLOAD;
 
-	if (PSP_CoreParameter().compat.flags().VertexDepthRounding) {
+	if (!g_Config.bHighQualityDepth) {
+		features |= GPU_SCALE_DEPTH_FROM_24BIT_TO_16BIT;
+	} else if (PSP_CoreParameter().compat.flags().VertexDepthRounding) {
 		features |= GPU_ROUND_DEPTH_TO_16BIT;
 	}
 

GPU/GLES/GLES_GPU.cpp

@@ -565,13 +565,15 @@ void GLES_GPU::CheckGPUFeatures() {
 	if (gl_extensions.GLES3 || !gl_extensions.IsGLES)
 		features |= GPU_SUPPORTS_TEXTURE_LOD_CONTROL;
 
-	// In the future, also disable this when we get a proper 16-bit depth buffer.
+	if (!g_Config.bHighQualityDepth) {
-	if ((!gl_extensions.IsGLES || gl_extensions.GLES3) && PSP_CoreParameter().compat.flags().PixelDepthRounding) {
+		features |= GPU_SCALE_DEPTH_FROM_24BIT_TO_16BIT;
-		features |= GPU_ROUND_FRAGMENT_DEPTH_TO_16BIT;
+	} else if (PSP_CoreParameter().compat.flags().PixelDepthRounding) {
-	} else {
+		if (!gl_extensions.IsGLES || gl_extensions.GLES3) {
-		if (PSP_CoreParameter().compat.flags().VertexDepthRounding) {
+			// Use fragment rounding on desktop and GLES3, most accurate.
-			features |= GPU_ROUND_DEPTH_TO_16BIT;
+			features |= GPU_ROUND_FRAGMENT_DEPTH_TO_16BIT;
 		}
+	} else if (PSP_CoreParameter().compat.flags().VertexDepthRounding) {
+		features |= GPU_ROUND_DEPTH_TO_16BIT;
 	}
 
 #ifdef MOBILE_DEVICE

GPU/GPUState.h

@@ -458,6 +458,7 @@ enum {
 	GPU_SUPPORTS_VAO = FLAG_BIT(18),
 	GPU_SUPPORTS_ANY_COPY_IMAGE = FLAG_BIT(19),
 	GPU_SUPPORTS_ANY_FRAMEBUFFER_FETCH = FLAG_BIT(20),
+	GPU_SCALE_DEPTH_FROM_24BIT_TO_16BIT = FLAG_BIT(21),
 	GPU_ROUND_FRAGMENT_DEPTH_TO_16BIT = FLAG_BIT(22),
 	GPU_ROUND_DEPTH_TO_16BIT = FLAG_BIT(23),  // Can be disabled either per game or if we use a real 16-bit depth buffer
 	GPU_SUPPORTS_TEXTURE_LOD_CONTROL = FLAG_BIT(24),