diff --git a/engine/client/render.h b/engine/client/render.h
index 74917d786..e286e22e1 100644
--- a/engine/client/render.h
+++ b/engine/client/render.h
@@ -302,6 +302,7 @@ typedef struct
 	int			recurse;			/*in a mirror/portal/half way through drawing something else*/
 	qboolean	forcevis;			/*if true, vis comes from the forcedvis field instead of recalculated*/
 	unsigned int	flipcull;		/*reflected/flipped view, requires inverted culling (should be set to SHADER_CULL_FLIPPED or 0 - its implemented as a xor)*/
+	unsigned int	colourmask;		/*shaderbits mask. anything not here will be forced to 0. this is for red/green type stereo*/
 	qboolean	useperspective;		/*not orthographic*/
 
 	stereomethod_t stereomethod;
diff --git a/engine/gl/gl_backend.c b/engine/gl/gl_backend.c
index 169473b05..14d4d4926 100644
--- a/engine/gl/gl_backend.c
+++ b/engine/gl/gl_backend.c
@@ -410,6 +410,9 @@ void GL_ForceDepthWritable(void)
 		shaderstate.shaderbits |= SBITS_MISC_DEPTHWRITE;
 		qglDepthMask(GL_TRUE);
 	}
+
+	qglColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+	shaderstate.shaderbits |= SBITS_MASK_BITS;
 }
 
 void GL_SetShaderState2D(qboolean is2d)
@@ -2915,6 +2918,7 @@ static void BE_SendPassBlendDepthMask(unsigned int sbits)
 				sbits |= SBITS_MISC_DEPTHWRITE;
 		}
 	}
+	sbits |= r_refdef.colourmask;
 
 
 	delta = sbits^shaderstate.shaderbits;
diff --git a/engine/gl/gl_draw.c b/engine/gl/gl_draw.c
index c06900e5b..f8338c7cb 100644
--- a/engine/gl/gl_draw.c
+++ b/engine/gl/gl_draw.c
@@ -689,6 +689,7 @@ void GL_Set2D (qboolean flipped)
 		r_refdef.flipcull = SHADER_CULL_FLIP;
 	else
 		r_refdef.flipcull = 0;
+	r_refdef.colourmask = 0u;
 
 	GL_SetShaderState2D(true);
 }
diff --git a/engine/gl/gl_rmain.c b/engine/gl/gl_rmain.c
index 8ee50e5f3..e2a76f450 100644
--- a/engine/gl/gl_rmain.c
+++ b/engine/gl/gl_rmain.c
@@ -705,6 +705,7 @@ r_refdef must be set before the first call
 */
 static void R_RenderScene_Internal(void)
 {
+	extern qboolean depthcleared;
 	int tmpvisents = cl_numvisedicts;
 	TRACE(("dbg: calling R_SetFrustrum\n"));
 	if (!r_refdef.recurse)
@@ -728,9 +729,12 @@ static void R_RenderScene_Internal(void)
 		RQ_RenderBatchClear();
 
 	cl_numvisedicts = tmpvisents;
+
+	depthcleared = false;	//whatever is in the depth buffer is no longer useful.
 }
 static void R_RenderEyeScene (texid_t rendertarget, vec4_t fovoverride, vec3_t axisorigin[4])
 {
+	extern qboolean depthcleared;
 	refdef_t refdef = r_refdef;
 	int pw = vid.fbpwidth;
 	int ph = vid.fbpheight;
@@ -741,6 +745,7 @@ static void R_RenderEyeScene (texid_t rendertarget, vec4_t fovoverride, vec3_t a
 		r = GLBE_FBO_Update(&fbo_vr, FBO_RB_DEPTH, &rendertarget, 1, r_nulltex,  rendertarget->width, rendertarget->height, 0);
 		GL_ForceDepthWritable();
 		qglClear (GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
+		depthcleared = true;
 		vid.fbpwidth = rendertarget->width;
 		vid.fbpheight = rendertarget->height;
 	}
@@ -766,8 +771,11 @@ static void R_RenderScene (void)
 	int stereomode;
 	int i;
 	int cull = r_refdef.flipcull;
+	unsigned int colourmask = r_refdef.colourmask;
 	vec3_t axisorg[4], ang;
+	extern qboolean		depthcleared;
 
+	r_refdef.colourmask = 0u;
 	stereomode = r_refdef.stereomethod;
 	if (stereomode == STEREO_QUAD)
 	{
@@ -780,7 +788,7 @@ static void R_RenderScene (void)
 	}
 
 
-	if (r_refdef.recurse || !stereomode || !r_stereo_separation.value)
+	if (r_refdef.recurse || !stereomode)// || !(r_stereo_separation.value||r_stereo_convergence.value))
 	{
 		stereooffset[0] = 0;
 		stereoframes = 1;
@@ -800,7 +808,6 @@ static void R_RenderScene (void)
 	{
 		GL_ForceDepthWritable();
 		qglClear (GL_DEPTH_BUFFER_BIT);
-		r_framecount++;
 
 		R_SetupGL (NULL, NULL, NULL, NULL);
 		R_RenderScene_Internal();
@@ -823,6 +830,7 @@ static void R_RenderScene (void)
 #endif
 	else for (i = 0; i < stereoframes; i++)
 	{
+		r_refdef.colourmask = 0u;
 		switch (stereomode)
 		{
 		default:
@@ -840,21 +848,21 @@ static void R_RenderScene (void)
 #endif
 		case STEREO_RED_CYAN:	//red/cyan(green+blue)
 			if (stereooffset[i] < 0)
-				qglColorMask(GL_TRUE, GL_FALSE, GL_FALSE, GL_TRUE);
+				r_refdef.colourmask = (SBITS_MASK_GREEN|SBITS_MASK_BLUE);
 			else
-				qglColorMask(GL_FALSE, GL_TRUE, GL_TRUE, GL_TRUE);
+				r_refdef.colourmask = SBITS_MASK_RED;
 			break;
 		case STEREO_RED_BLUE: //red/blue
 			if (stereooffset[i] < 0)
-				qglColorMask(GL_TRUE, GL_FALSE, GL_FALSE, GL_TRUE);
+				r_refdef.colourmask = (SBITS_MASK_GREEN|SBITS_MASK_BLUE);
 			else
-				qglColorMask(GL_FALSE, GL_FALSE, GL_TRUE, GL_TRUE);
+				r_refdef.colourmask = (SBITS_MASK_RED|SBITS_MASK_GREEN);
 			break;
 		case STEREO_RED_GREEN:	//red/green
 			if (stereooffset[i] < 0)
-				qglColorMask(GL_TRUE, GL_FALSE, GL_FALSE, GL_TRUE);
+				r_refdef.colourmask = (SBITS_MASK_GREEN|SBITS_MASK_BLUE);
 			else
-				qglColorMask(GL_FALSE, GL_TRUE, GL_FALSE, GL_TRUE);
+				r_refdef.colourmask = (SBITS_MASK_RED|SBITS_MASK_BLUE);
 			break;
 #ifdef FTE_TARGET_WEB
 		case STEREO_WEBVR:
@@ -873,17 +881,19 @@ static void R_RenderScene (void)
 			//fixme: depth buffer doesn't need clearing
 			break;
 		}
-		if (i)
+
+		if (!depthcleared)
 		{
 			GL_ForceDepthWritable();
 			qglClear (GL_DEPTH_BUFFER_BIT);
-			r_framecount++;
+			depthcleared = true;
 		}
+		r_framecount++;	//view position changes, if only slightly. which means we need to rebuild vis info. :(
 
 		ang[0] = 0;
 		ang[1] = r_stereo_convergence.value * (i?0.5:-0.5);
-		ang[2] = 0;;
-		AngleVectors(ang, axisorg[0], axisorg[1], axisorg[2]);
+		ang[2] = 0;
+		AngleVectorsFLU(ang, axisorg[0], axisorg[1], axisorg[2]);
 		axisorg[3][0] = 0;
 		axisorg[3][1] = stereooffset[i];
 		axisorg[3][2] = 0;
@@ -904,13 +914,13 @@ static void R_RenderScene (void)
 	case STEREO_RED_BLUE:	//green should have already been cleared.
 	case STEREO_RED_GREEN:	//blue should have already been cleared.
 	case STEREO_RED_CYAN:
-		qglColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 		break;
 	case 5:
 		break;
 	}
 
 	r_refdef.flipcull = cull;
+	r_refdef.colourmask = colourmask;
 }
 /*generates a new modelview matrix, as well as vpn vectors*/
 static void R_MirrorMatrix(plane_t *plane)
@@ -1459,7 +1469,6 @@ void R_Clear (qboolean fbo)
 {
 	/*tbh, this entire function should be in the backend*/
 	{
-		qglColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);	//FIXME: breaks backend!
 		if (!depthcleared || fbo)
 		{
 			GL_ForceDepthWritable();
@@ -1468,7 +1477,10 @@ void R_Clear (qboolean fbo)
 			//but for multiple scenes, we do need to clear depth still.
 			//fbos always get cleared depth, just in case (colour fbos may contain junk, but hey).
 			if ((fbo && r_clear.ival) || r_refdef.stereomethod==STEREO_RED_BLUE||r_refdef.stereomethod==STEREO_RED_GREEN)
+			{
+				qglClearColor(0, 0, 0, 1);
 				qglClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
+			}
 			else
 				qglClear (GL_DEPTH_BUFFER_BIT);
 		}
diff --git a/engine/gl/gl_shadow.c b/engine/gl/gl_shadow.c
index 364ade9f6..3016044b6 100644
--- a/engine/gl/gl_shadow.c
+++ b/engine/gl/gl_shadow.c
@@ -2331,6 +2331,7 @@ static void Sh_GenShadowFace(dlight_t *l, vec3_t axis[3], int lighttype, shadowm
 
 	if (lighttype & LSHADER_FAKESHADOWS)
 		r_refdef.flipcull ^= SHADER_CULL_FLIP;
+	r_refdef.colourmask = 0u;
 
 #ifdef SHADOWDBG_COLOURNOTDEPTH
 	BE_SelectMode(BEM_STANDARD);
@@ -2448,6 +2449,7 @@ qboolean Sh_GenShadowMap (dlight_t *l, int lighttype, vec3_t axis[3], qbyte *lvi
 	shadowmesh_t *smesh;
 	int sidevisible;
 	int oldflip = r_refdef.flipcull;
+	unsigned int oldcolourmask = r_refdef.colourmask;
 	int oldexternalview = r_refdef.externalview;
 	int twidth;
 	int theight;
@@ -2593,6 +2595,7 @@ qboolean Sh_GenShadowMap (dlight_t *l, int lighttype, vec3_t axis[3], qbyte *lvi
 	r_refdef.pxrect = oprect;
 
 	r_refdef.flipcull = oldflip;
+	r_refdef.colourmask = oldcolourmask;
 	r_refdef.externalview = oldexternalview;
 	R_SetFrustum(r_refdef.m_projection_std, r_refdef.m_view);