Merge pull request #7069 from level99procrastinator/depth-range-hack-for-psp2

Workaround for graphics glitch in Phantasy Star Portable 2

Core/Config.cpp

@@ -451,6 +451,7 @@ static ConfigSetting graphicsSettings[] = {
 	ConfigSetting("VSyncInterval", &g_Config.bVSync, false),
 	ReportedConfigSetting("DisableStencilTest", &g_Config.bDisableStencilTest, false),
 	ReportedConfigSetting("AlwaysDepthWrite", &g_Config.bAlwaysDepthWrite, false),
+	ReportedConfigSetting("DepthRangeHack", &g_Config.bDepthRangeHack, false),
 
 	// Not really a graphics setting...
 	ReportedConfigSetting("TimerHack", &g_Config.bTimerHack, &DefaultTimerHack),

Core/Config.h

@@ -165,6 +165,7 @@ public:
 	bool bReloadCheats;
 	bool bDisableStencilTest;
 	bool bAlwaysDepthWrite;
+	bool bDepthRangeHack;
 	bool bTimerHack;
 	bool bAlphaMaskHack;
 	bool bBlockTransferGPU;

GPU/GLES/ShaderManager.cpp

@@ -388,6 +388,39 @@ void LinkedShader::UpdateUniforms(u32 vertType) {
 			flippedMatrix[0] = -flippedMatrix[0];
 			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 (g_Config.bDepthRangeHack) {
+			float zScale = getFloat24(gstate.viewportz1) / 65535.0f;
+			float zOff = getFloat24(gstate.viewportz2) / 65535.0f;
+
+			// if far depth range < 0
+			if (zOff + 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 + ((zOff + 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;
+					}
+				}
+			}
+		}
+
 		glUniformMatrix4fv(u_proj, 1, GL_FALSE, flippedMatrix);
 	}
 	if (dirty & DIRTY_PROJTHROUGHMATRIX)

UI/GameSettingsScreen.cpp

@@ -278,6 +278,9 @@ void GameSettingsScreen::CreateViews() {
 	CheckBox *prescale = graphicsSettings->Add(new CheckBox(&g_Config.bPrescaleUV, gs->T("Texture Coord Speedhack")));
 	prescale->SetDisabledPtr(&g_Config.bSoftwareRendering);
 
+	CheckBox *depthRange = graphicsSettings->Add(new CheckBox(&g_Config.bDepthRangeHack, gs->T("Depth Range Hack (Phantasy Star Portable 2)")));
+	depthRange->SetDisabledPtr(&g_Config.bSoftwareRendering);
+
 	graphicsSettings->Add(new ItemHeader(gs->T("Overlay Information")));
 	static const char *fpsChoices[] = {
 		"None", "Speed", "FPS", "Both"