From f20adec008541b59e0000bdabf6cc262d6c92a80 Mon Sep 17 00:00:00 2001
From: havoc <havoc@d7cf8633-e32d-0410-b094-e92efae38249>
Date: Mon, 9 Apr 2018 05:58:15 +0000
Subject: [PATCH] Improved r_sky_scissor - scissor box is tighter as it now
 computes scissor box for each surface and combines them.

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@12380 d7cf8633-e32d-0410-b094-e92efae38249
---
 gl_rmain.c | 43 +++++++++++++++++++++++++++++++++----------
 r_sky.c    | 17 ++++++-----------
 render.h   |  4 +---
 3 files changed, 40 insertions(+), 24 deletions(-)

diff --git a/gl_rmain.c b/gl_rmain.c
index a51d300f..e02f6551 100644
--- a/gl_rmain.c
+++ b/gl_rmain.c
@@ -10529,25 +10529,48 @@ static void R_DrawTextureSurfaceList_Sky(int texturenumsurfaces, const msurface_
 			const msurface_t *surf = texturesurfacelist[i];
 			const float *v;
 			float p[3];
+			float mins[3], maxs[3];
+			int scissor[4];
 			for (j = 0, v = rsurface.batchvertex3f + 3 * surf->num_firstvertex; j < surf->num_vertices; j++, v += 3)
 			{
 				Matrix4x4_Transform(&rsurface.matrix, v, p);
-				if (skyscissor)
+				if (j > 0)
 				{
-					if (skyscissormins[0] > p[0]) skyscissormins[0] = p[0];
-					if (skyscissormins[1] > p[1]) skyscissormins[1] = p[1];
-					if (skyscissormins[2] > p[2]) skyscissormins[2] = p[2];
-					if (skyscissormaxs[0] < p[0]) skyscissormaxs[0] = p[0];
-					if (skyscissormaxs[1] < p[1]) skyscissormaxs[1] = p[1];
-					if (skyscissormaxs[2] < p[2]) skyscissormaxs[2] = p[2];
+					if (mins[0] > p[0]) mins[0] = p[0];
+					if (mins[1] > p[1]) mins[1] = p[1];
+					if (mins[2] > p[2]) mins[2] = p[2];
+					if (maxs[0] < p[0]) maxs[0] = p[0];
+					if (maxs[1] < p[1]) maxs[1] = p[1];
+					if (maxs[2] < p[2]) maxs[2] = p[2];
 				}
 				else
 				{
-					VectorCopy(p, skyscissormins);
-					VectorCopy(p, skyscissormaxs);
-					skyscissor = true;
+					VectorCopy(p, mins);
+					VectorCopy(p, maxs);
 				}
 			}
+			if (!R_ScissorForBBox(mins, maxs, scissor))
+			{
+				if (skyscissor[2])
+				{
+					if (skyscissor[0] > scissor[0])
+					{
+						skyscissor[2] += skyscissor[0] - scissor[0];
+						skyscissor[0] = scissor[0];
+					}
+					if (skyscissor[1] > scissor[1])
+					{
+						skyscissor[3] += skyscissor[1] - scissor[1];
+						skyscissor[1] = scissor[1];
+					}
+					if (skyscissor[0] + skyscissor[2] < scissor[0] + scissor[2])
+						skyscissor[2] = scissor[0] + scissor[2] - skyscissor[0];
+					if (skyscissor[1] + skyscissor[3] < scissor[1] + scissor[3])
+						skyscissor[3] = scissor[1] + scissor[3] - skyscissor[1];
+				}
+				else
+					Vector4Copy(scissor, skyscissor);
+			}
 		}
 	}
 
diff --git a/r_sky.c b/r_sky.c
index bf338240..17754782 100644
--- a/r_sky.c
+++ b/r_sky.c
@@ -9,9 +9,7 @@ cvar_t r_skyscroll2 = {CVAR_SAVE, "r_skyscroll2", "2", "speed at which lower clo
 cvar_t r_sky_scissor = {0, "r_sky_scissor", "1", "limit rendering of sky to approximately the area of the sky surfaces"};
 int skyrenderlater;
 int skyrendermasked;
-int skyscissor;
-float skyscissormins[3];
-float skyscissormaxs[3];
+int skyscissor[4];
 
 static int skyrendersphere;
 static int skyrenderbox;
@@ -64,9 +62,7 @@ void R_SkyStartFrame(void)
 	// for depth-masked sky, we need to know whether any sky was rendered
 	skyrenderlater = false;
 	// we can scissor the sky to just the relevant area
-	skyscissor = false;
-	VectorClear(skyscissormins);
-	VectorClear(skyscissormaxs);
+	Vector4Clear(skyscissor);
 	if (r_sky.integer)
 	{
 		if (skyboxskinframe[0] || skyboxskinframe[1] || skyboxskinframe[2] || skyboxskinframe[3] || skyboxskinframe[4] || skyboxskinframe[5])
@@ -406,16 +402,15 @@ static void R_SkySphere(void)
 
 void R_Sky(void)
 {
-	int scissor[4];
 	Matrix4x4_CreateFromQuakeEntity(&skymatrix, r_refdef.view.origin[0], r_refdef.view.origin[1], r_refdef.view.origin[2], 0, 0, 0, r_refdef.farclip * (0.5f / 16.0f));
 	Matrix4x4_Invert_Simple(&skyinversematrix, &skymatrix);
 
-	if (r_sky_scissor.integer && skyscissor)
+	if (r_sky_scissor.integer)
 	{
-		// compute the scissor, if it's offscreen just return
-		if (R_ScissorForBBox(skyscissormins, skyscissormaxs, scissor))
+		// if the scissor is empty just return
+		if (skyscissor[2] == 0 || skyscissor[3] == 0)
 			return;
-		GL_Scissor(scissor[0], scissor[1], scissor[2], scissor[3]);
+		GL_Scissor(skyscissor[0], skyscissor[1], skyscissor[2], skyscissor[3]);
 		GL_ScissorTest(true);
 	}
 	if (skyrendersphere)
diff --git a/render.h b/render.h
index 0b54c35f..1d606827 100644
--- a/render.h
+++ b/render.h
@@ -36,9 +36,7 @@ extern cvar_t r_skyscroll2;
 extern cvar_t r_sky_scissor;
 extern cvar_t r_q3bsp_renderskydepth;
 extern int skyrenderlater, skyrendermasked;
-extern int skyscissor;
-extern float skyscissormins[3];
-extern float skyscissormaxs[3];
+extern int skyscissor[4];
 int R_SetSkyBox(const char *sky);
 void R_SkyStartFrame(void);
 void R_Sky(void);
-- 
2.39.2