Quick attempt at skyrooms. Seems to work for me. Note that the server's pvs is not opened, nor have I tried to depthmask sky surfaces to avoid leakage. _skyroom "x y z" in worldspawn to use.

Quake/gl_rmain.c

@@ -530,7 +530,7 @@ void R_Clear (void)
 	// from mh -- if we get a stencil buffer, we should clear it, even though we don't use it
 	if (gl_stencilbits)
 		clearbits |= GL_STENCIL_BUFFER_BIT;
-	if (gl_clear.value)
+	if (gl_clear.value && !skyroom_drawn)
 		clearbits |= GL_COLOR_BUFFER_BIT;
 	glClear (clearbits);
 }
@@ -591,6 +591,7 @@ void R_SetupView (void)
 
 	R_CullSurfaces (); //johnfitz -- do after R_SetFrustum and R_MarkSurfaces
 
+	if (!skyroom_drawn)
 		R_UpdateWarpTextures (); //johnfitz -- do this before R_Clear
 
 	R_Clear ();
@@ -1069,6 +1070,22 @@ void R_ScaleView (void)
 	GL_ClearBindings ();
 }
 
+static qboolean R_SkyroomWasVisible(void)
+{
+	qmodel_t *model = cl.worldmodel;
+	texture_t *t;
+	size_t i;
+	if (!skyroom_enabled)
+		return false;
+	for (i=0 ; i<model->numtextures ; i++)
+	{
+		t = model->textures[i];
+		if (t && t->texturechains[chain_world] && t->texturechains[chain_world]->flags & SURF_DRAWSKY)
+			return true;
+	}
+	return false;
+}
+
 /*
 ================
 R_RenderView
@@ -1076,6 +1093,7 @@ R_RenderView
 */
 void R_RenderView (void)
 {
+	static qboolean skyroom_visible;
 	double	time1, time2;
 
 	if (r_norefresh.value)
@@ -1097,6 +1115,23 @@ void R_RenderView (void)
 	else if (gl_finish.value)
 		glFinish ();
 
+	//Spike -- quickly draw the world from the skyroom camera's point of view.
+	skyroom_drawn = false;
+	if (skyroom_enabled && skyroom_visible)
+	{
+		vec3_t vieworg;
+		VectorCopy(r_refdef.vieworg, vieworg);
+		VectorCopy(skyroom_origin, r_refdef.vieworg);
+		R_SetupView ();
+		//note: sky boxes are generally considered an 'infinite' distance away such that you'd not see paralax.
+		//that's my excuse for not handling r_stereo here, and I'm sticking to it.
+		R_RenderScene ();
+
+		VectorCopy(vieworg, r_refdef.vieworg);
+		skyroom_drawn = true;	//disable glClear(GL_COLOR_BUFFER_BIT)
+	}
+	//skyroom end
+
 	R_SetupView (); //johnfitz -- this does everything that should be done once per frame
 
 	//johnfitz -- stereo rendering -- full of hacky goodness
@@ -1135,6 +1170,14 @@ void R_RenderView (void)
 	}
 	//johnfitz
 
+	//Spike: flag whether the skyroom was actually visible, so we don't needlessly draw it when its not (1 frame's lag, hopefully not too noticable)
+	if (r_viewleaf->contents == CONTENTS_SOLID || r_drawflat_cheatsafe || r_lightmap_cheatsafe)
+		skyroom_visible = false;	//don't do skyrooms when the view is in the void, for framerate reasons while debugging.
+	else
+		skyroom_visible = R_SkyroomWasVisible();
+	skyroom_drawn = false;
+	//skyroom end
+
 	R_ScaleView ();
 
 	//johnfitz -- modified r_speeds output

Quake/gl_sky.c

@@ -35,6 +35,10 @@ extern	int rs_skypasses; //for r_speeds readout
 float	skyflatcolor[3];
 float	skymins[2][6], skymaxs[2][6];
 
+qboolean skyroom_drawn;
+qboolean skyroom_enabled;
+vec3_t skyroom_origin;
+
 char	skybox_name[1024]; //name of current skybox, or "" if no skybox
 
 gltexture_t	*skybox_textures[6];
@@ -225,6 +229,7 @@ void Sky_NewMap (void)
 	//
 	// initially no sky
 	//
+	skyroom_enabled = false;
 	skybox_name[0] = 0;
 	for (i=0; i<6; i++)
 		skybox_textures[i] = NULL;
@@ -263,8 +268,18 @@ void Sky_NewMap (void)
 
 		if (!strcmp("sky", key))
 			Sky_LoadSkyBox(value);
+		else if (!strcmp("skyroom", key))
+		{	//"_skyroom" "X Y Z". ideally the gamecode would do this with an entity, but people want to use the vanilla gamecode from 1996 for some reason.
+			const char *t = COM_Parse(value);
+			skyroom_origin[0] = atof(com_token);
+			t = COM_Parse(t);
+			skyroom_origin[1] = atof(com_token);
+			t = COM_Parse(t);
+			skyroom_origin[2] = atof(com_token);
+			skyroom_enabled = true;
+		}
 
-		if (!strcmp("skyfog", key))
+		else if (!strcmp("skyfog", key))
 			skyfog = atof(value);
 
 #if 1 //also accept non-standard keys
@@ -986,7 +1001,7 @@ void Sky_DrawSky (void)
 	int				i;
 
 	//in these special render modes, the sky faces are handled in the normal world/brush renderer
-	if (r_drawflat_cheatsafe || r_lightmap_cheatsafe )
+	if (r_drawflat_cheatsafe || r_lightmap_cheatsafe || skyroom_drawn)
 		return;
 
 	//

Quake/glquake.h

@@ -433,6 +433,9 @@ void Sky_DrawSky (void);
 void Sky_NewMap (void);
 void Sky_LoadTexture (texture_t *mt);
 void Sky_LoadSkyBox (const char *name);
+extern qboolean skyroom_drawn;		//we draw a skyroom this frame
+extern qboolean skyroom_enabled;	//we know where the skyroom is ...
+extern vec3_t skyroom_origin;		//... and it is here.
 
 void TexMgr_RecalcWarpImageSize (void);