use actual view to clip segs in ogl instead of calculated fov

thx dsda-doom!
basically better performance in alot of cases and technically should fix any future issues if someone plays on weird aspect ratios

src/hardware/hw_clip.c

@@ -79,12 +79,6 @@
 #include "r_opengl/r_opengl.h"
 #include "../r_main.h"	// for cv_fov
 
-#ifdef HAVE_SPHEREFRUSTRUM
-static GLdouble viewMatrix[16];
-static GLdouble projMatrix[16];
-float frustum[6][4];
-#endif
-
 typedef struct clipnode_s
 	{
 		struct clipnode_s *prev, *next;
@@ -322,16 +316,14 @@ void gld_clipper_Clear(void)
 
 #define RMUL (1.6f/1.333333f)
 
-angle_t gld_FrustumAngle(float render_fov, angle_t tiltangle)
+angle_t gld_FrustumAngle(angle_t tiltangle)
 {
+	double clipfov;
 	double floatangle;
 	angle_t a1;
 
 	float tilt = (float)fabs(((double)(int)tiltangle) / ANG1);
 
-	float render_fovratio = (float)BASEVIDWIDTH / (float)BASEVIDHEIGHT; // SRB2CBTODO: NEWCLIPTODO: Is this right?
-	float render_multiplier = 64.0f / render_fovratio / RMUL;
-
 	if (tilt > 90.0f)
 		tilt = 90.0f;
 
@@ -341,10 +333,11 @@ angle_t gld_FrustumAngle(float render_fov, angle_t tiltangle)
 
 	// ok, this is a gross hack that barely works...
 	// but at least it doesn't overestimate too much...
-	floatangle = 2.0f + (45.0f + (tilt / 1.9f)) * (float)render_fov * 48.0f / render_multiplier / 90.0f;
-	a1 = ANG1 * (int)floatangle;
-	if (a1 >= ANGLE_180)
+	clipfov = atan(1 / projMatrix[0]) * 360 / M_PI; // use the actual view of the scene
+	floatangle = 2.0f + (45.0f + (tilt / 1.9f)) * clipfov / 90.0f;
+	if (floatangle >= ANGLE_180)
 		return 0xffffffff;
+	a1 = (angle_t)(ANG1 * (int)floatangle);
 	return a1;
 }
 
@@ -357,6 +350,10 @@ angle_t gld_FrustumAngle(float render_fov, angle_t tiltangle)
 // gld_FrustrumSetup
 //
 
+static GLdouble viewMatrix[16];
+static GLdouble projMatrix[16];
+float frustum[6][4];
+
 #define CALCMATRIX(a, b, c, d, e, f, g, h)\
 (float)(viewMatrix[a] * projMatrix[b] + \
 viewMatrix[c] * projMatrix[d] + \

src/hardware/hw_clip.h

@@ -24,7 +24,7 @@ extern "C" {
 boolean gld_clipper_SafeCheckRange(angle_t startAngle, angle_t endAngle);
 void gld_clipper_SafeAddClipRange(angle_t startangle, angle_t endangle);
 void gld_clipper_Clear(void);
-angle_t gld_FrustumAngle(float render_fov, angle_t tiltangle);
+angle_t gld_FrustumAngle(angle_t tiltangle);
 #ifdef HAVE_SPHEREFRUSTRUM
 void gld_FrustrumSetup(void);
 boolean gld_SphereInFrustum(float x, float y, float z, float radius);

src/hardware/hw_main.c

@@ -5901,6 +5901,16 @@ static void HWR_SetShaderState(void)
 	HWD.pfnSetShader(SHADER_DEFAULT);
 }
 
+static void HWR_ClearClipper(void)
+{
+	angle_t a1 = gld_FrustumAngle(gl_aimingangle);
+	gld_clipper_Clear();
+	gld_clipper_SafeAddClipRange(viewangle + a1, viewangle - a1);
+#ifdef HAVE_SPHEREFRUSTRUM
+	gld_FrustrumSetup();
+#endif
+}
+
 // ==========================================================================
 // Same as rendering the player view, but from the skybox object
 // ==========================================================================
@@ -5985,19 +5995,12 @@ void HWR_RenderSkyboxView(player_t *player)
 
 	drawcount = 0;
 
-	{
-		angle_t a1 = gld_FrustumAngle(fpov, gl_aimingangle);
-		gld_clipper_Clear();
-		gld_clipper_SafeAddClipRange(viewangle + a1, viewangle - a1);
-#ifdef HAVE_SPHEREFRUSTRUM
-		gld_FrustrumSetup();
-#endif
-	}
-
 	//04/01/2000: Hurdler: added for T&L
 	//                     Actually it only works on Walls and Planes
 	HWD.pfnSetTransform(&atransform);
 
+	HWR_ClearClipper();
+
 	// Reset the shader state.
 	HWR_SetShaderState();
 
@@ -6167,18 +6170,12 @@ void HWR_RenderPlayerView(void)
 
 	drawcount = 0;
 
-	{
-		angle_t a1 = gld_FrustumAngle(fpov, gl_aimingangle);
-		gld_clipper_Clear();
-		gld_clipper_SafeAddClipRange(viewangle + a1, viewangle - a1);
-#ifdef HAVE_SPHEREFRUSTRUM
-		gld_FrustrumSetup();
-#endif
-	}
 	//04/01/2000: Hurdler: added for T&L
 	//                     Actually it only works on Walls and Planes
 	HWD.pfnSetTransform(&atransform);
 
+	HWR_ClearClipper();
+
 	// Reset the shader state.
 	HWR_SetShaderState();
 

src/hardware/r_opengl/r_opengl.c

@@ -86,7 +86,7 @@ const GLubyte *gl_extensions = NULL;
 
 //Hurdler: 04/10/2000: added for the kick ass coronas as Boris wanted;-)
 static GLfloat modelMatrix[16];
-static GLfloat projMatrix[16];
+GLfloat projMatrix[16];
 static GLint   viewport[4];
 
 // Sryder:	NextTexAvail is broken for these because palette changes or changes to the texture filter or antialiasing

src/hardware/r_opengl/r_opengl.h

@@ -73,6 +73,8 @@ extern "C" {
 extern FILE             *gllogstream;
 #endif
 
+extern GLfloat projMatrix[16];
+
 // ==========================================================================
 //                                                                     PROTOS
 // ==========================================================================