Bring back the depth range hack.

Core/Compatibility.cpp

@@ -47,6 +47,7 @@ void Compatibility::Clear() {
 void Compatibility::CheckSettings(IniFile &iniFile, const std::string &gameID) {
 	CheckSetting(iniFile, gameID, "VertexDepthRounding", flags_.VertexDepthRounding);
 	CheckSetting(iniFile, gameID, "PixelDepthRounding", flags_.PixelDepthRounding);
+	CheckSetting(iniFile, gameID, "DepthRangeHack", flags_.DepthRangeHack);
 }
 
 void Compatibility::CheckSetting(IniFile &iniFile, const std::string &gameID, const char *option, bool &flag) {

Core/Compatibility.h

@@ -47,6 +47,7 @@
 struct CompatFlags {
 	bool VertexDepthRounding;
 	bool PixelDepthRounding;
+	bool DepthRangeHack;
 };
 
 class IniFile;

GPU/GLES/GLES_GPU.cpp

@@ -586,6 +586,11 @@ void GLES_GPU::CheckGPUFeatures() {
 		}
 	}
 
+	// The Phantasy Star hack :(
+	if (PSP_CoreParameter().compat.flags().DepthRangeHack && (features & GPU_SUPPORTS_ACCURATE_DEPTH) == 0) {
+		features |= GPU_USE_DEPTH_RANGE_HACK;
+	}
+
 #ifdef MOBILE_DEVICE
 	// Arguably, we should turn off GPU_IS_MOBILE on like modern Tegras, etc.
 	features |= GPU_IS_MOBILE;

GPU/GLES/ShaderManager.cpp

@@ -437,6 +437,38 @@ void LinkedShader::UpdateUniforms(u32 vertType, const ShaderID &vsid) {
 			flippedMatrix[12] = -flippedMatrix[12];
 		}
 
+		// In Phantasy Star Portable 2, depth range sometimes goes negative and is clamped by glDepthRange to 0,
+		// causing graphics clipping glitch (issue #1788). This hack modifies the projection matrix to work around it.
+		if (gstate_c.Supports(GPU_USE_DEPTH_RANGE_HACK)) {
+			float zScale = gstate.getViewportZScale() / 65535.0f;
+			float zCenter = gstate.getViewportZCenter() / 65535.0f;
+
+			// if far depth range < 0
+			if (zCenter + zScale < 0.0f) {
+				// if perspective projection
+				if (flippedMatrix[11] < 0.0f) {
+					float depthMax = gstate.getDepthRangeMax() / 65535.0f;
+					float depthMin = gstate.getDepthRangeMin() / 65535.0f;
+
+					float a = flippedMatrix[10];
+					float b = flippedMatrix[14];
+
+					float n = b / (a - 1.0f);
+					float f = b / (a + 1.0f);
+
+					f = (n * f) / (n + ((zCenter + zScale) * (n - f) / (depthMax - depthMin)));
+
+					a = (n + f) / (n - f);
+					b = (2.0f * n * f) / (n - f);
+
+					if (!my_isnan(a) && !my_isnan(b)) {
+						flippedMatrix[10] = a;
+						flippedMatrix[14] = b;
+					}
+				}
+			}
+		}
+
 		ScaleProjMatrix(flippedMatrix);
 
 		glUniformMatrix4fv(u_proj, 1, GL_FALSE, flippedMatrix.m);

GPU/GPUState.h

@@ -455,6 +455,7 @@ enum {
 	GPU_SUPPORTS_UNPACK_SUBIMAGE = FLAG_BIT(3),
 	GPU_SUPPORTS_BLEND_MINMAX = FLAG_BIT(4),
 	GPU_SUPPORTS_LOGIC_OP = FLAG_BIT(5),
+	GPU_USE_DEPTH_RANGE_HACK = FLAG_BIT(6),
 	GPU_SUPPORTS_ACCURATE_DEPTH = FLAG_BIT(17),
 	GPU_SUPPORTS_VAO = FLAG_BIT(18),
 	GPU_SUPPORTS_ANY_COPY_IMAGE = FLAG_BIT(19),

assets/compat.ini

@@ -87,3 +87,17 @@ NPJH90002 = true
 # Phantasy Star Portable 2 JP Demo
 ULJM91018 = true
 NPJH90062 = true
+
+[DepthRangeHack]
+# Phantasy Star Portable 2 and Infinity both use viewport depth outside [0, 1].
+# This gets clamped in our current implementation, but attempts to fix it run into
+# Other bugs, so we've restored this hack for now.
+ULJM05493 = true
+NPJH50043 = true
+ULJM08030 = true
+ULES01439 = true
+ULUS10529 = true
+ULJM91018 = true  # Infinity demo disc?
+NPJH90157 = true  # Infinity demo
+ULJM05732 = true
+NPJH50332 = true