From 08b8d305899f4d09583df118cfe6ff8e522861c3 Mon Sep 17 00:00:00 2001
From: Flyinghead <raphael.jean@gmail.com>
Date: Wed, 2 May 2018 15:41:42 +0200
Subject: [PATCH] Implement clipping. Enabled by default.

---
 core/nullDC.cpp           |  1 +
 core/rend/gles/gldraw.cpp | 26 ++++++++++++++++++++------
 core/rend/gles/gles.cpp   | 15 ++++++++++++++-
 core/types.h              |  1 +
 4 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/core/nullDC.cpp b/core/nullDC.cpp
index c62db04e8..6c8ac67f0 100755
--- a/core/nullDC.cpp
+++ b/core/nullDC.cpp
@@ -244,6 +244,7 @@ void LoadSettings()
 	settings.rend.UseMipmaps		= cfgLoadInt("config","rend.UseMipmaps",1);
 	settings.rend.WideScreen		= cfgLoadInt("config","rend.WideScreen",0);
 	settings.rend.ModifierVolumes	= cfgLoadInt("config","rend.ModifierVolumes",1);
+	settings.rend.Clipping			= cfgLoadInt("config","rend.Clipping",1);
 	
 	settings.pvr.subdivide_transp	= cfgLoadInt("config","pvr.Subdivide",0);
 	
diff --git a/core/rend/gles/gldraw.cpp b/core/rend/gles/gldraw.cpp
index ed0ae7a3a..ded55e1d4 100644
--- a/core/rend/gles/gldraw.cpp
+++ b/core/rend/gles/gldraw.cpp
@@ -74,6 +74,8 @@ const static u32 SrcBlendGL[] =
 	GL_ONE_MINUS_DST_ALPHA
 };
 
+extern int screen_width;
+extern int screen_height;
 
 PipelineShader* CurrentShader;
 u32 gcflip;
@@ -106,6 +108,9 @@ static struct
 
 s32 SetTileClip(u32 val, bool set)
 {
+	if (!settings.rend.Clipping)
+		return 0;
+
 	/*
 	if (set)
 	{
@@ -121,9 +126,9 @@ s32 SetTileClip(u32 val, bool set)
 		clip_mode=0;    //always passes
 	}
 	else if (clipmode&1)
-		clip_mode=-1;   //render stuff inside the region
+		clip_mode=-1;   //render stuff outside the region
 	else
-		clip_mode=1;    //render stuff outside the region
+		clip_mode=1;    //render stuff inside the region
 
 	float csx=0,csy=0,cex=0,cey=0;
 
@@ -137,11 +142,20 @@ s32 SetTileClip(u32 val, bool set)
 	csy=csy*32;
 	cey=cey*32 +32;
 
-	if (csx==0 && csy==0 && cex==640 && cey==480)
+	if (csx <= 0 && csy <= 0 && cex >= 640 && cey >= 480)
 		return 0;
 	
-	if (set)
-		glUniform4f(CurrentShader->pp_ClipTest,-csx,-csy,-cex,-cey);		
+	if (set && clip_mode) {
+		csy = 480 - csy;
+		cey = 480 - cey;
+		float dc2s_scale_h = screen_height / 480.0f;
+		float ds2s_offs_x = (screen_width - dc2s_scale_h * 640) / 2;
+		csx = csx * dc2s_scale_h + ds2s_offs_x;
+		cex = cex * dc2s_scale_h + ds2s_offs_x;
+		csy = csy * dc2s_scale_h;
+		cey = cey * dc2s_scale_h;
+		glUniform4f(CurrentShader->pp_ClipTest, csx, cey, cex, csy);
+	}
 
 	return clip_mode;
 }
@@ -173,8 +187,8 @@ __forceinline
 	{
 		cache.program=CurrentShader->program;
 		glUseProgram(CurrentShader->program);
-		SetTileClip(gp->tileclip,true);
 	}
+	SetTileClip(gp->tileclip,true);
 
 	//This for some reason doesn't work properly
 	//So, shadow bit emulation is disabled.
diff --git a/core/rend/gles/gles.cpp b/core/rend/gles/gles.cpp
index ef16af4e9..f6c208eec 100755
--- a/core/rend/gles/gles.cpp
+++ b/core/rend/gles/gles.cpp
@@ -233,7 +233,7 @@ const char* PixelPipelineShader =
 "\
 \
 #define cp_AlphaTest %d \n\
-#define pp_ClipTestMode %d.0 \n\
+#define pp_ClipTestMode %d \n\
 #define pp_UseAlpha %d \n\
 #define pp_Texture %d \n\
 #define pp_IgnoreTexA %d \n\
@@ -259,6 +259,19 @@ lowp float fog_mode2(highp float val) \n\
 } \n\
 void main() \n\
 { \n\
+	// Clip outside the box \n\
+	#if pp_ClipTestMode==1 \n\
+		if (gl_FragCoord.x < pp_ClipTest.x || gl_FragCoord.x > pp_ClipTest.z \n\
+				|| gl_FragCoord.y < pp_ClipTest.y || gl_FragCoord.y > pp_ClipTest.w) \n\
+			discard; \n\
+	#endif \n\
+	// Clip inside the box \n\
+	#if pp_ClipTestMode==-1 \n\
+		if (gl_FragCoord.x >= pp_ClipTest.x && gl_FragCoord.x <= pp_ClipTest.z \n\
+				&& gl_FragCoord.y >= pp_ClipTest.y && gl_FragCoord.y <= pp_ClipTest.w) \n\
+			discard; \n\
+	#endif \n\
+	\n\
 	lowp vec4 color=vtx_base; \n\
 	#if pp_UseAlpha==0 \n\
 		color.a=1.0; \n\
diff --git a/core/types.h b/core/types.h
index 24df94bde..b9c6333c9 100644
--- a/core/types.h
+++ b/core/types.h
@@ -616,6 +616,7 @@ struct settings_t
 		bool UseMipmaps;
 		bool WideScreen;
 		bool ModifierVolumes;
+		bool Clipping;
 	} rend;
 
 	struct