gzdoom/wadsrc/static/shaders/glsl/main.vp

in vec4 aPosition;
in vec2 aTexCoord;
in vec4 aColor;
#ifndef SIMPLE	// we do not need these for simple shaders
in vec4 aVertex2;
out vec4 pixelpos;
out vec2 glowdist;
#endif

out vec4 vTexCoord;
out vec4 vColor;

void main()
{
	vec2 parmTexCoord;
	vec4 parmPosition;
	
	#ifndef USE_QUAD_DRAWER
		parmTexCoord = aTexCoord;
		parmPosition = aPosition;
	#else
		if (uQuadMode == 0)
		{
			parmTexCoord = aTexCoord;
			parmPosition = aPosition;
		}
		else
		{
			parmPosition = uQuadVertices[int(aPosition.x)];
			parmTexCoord = uQuadTexCoords[int(aPosition.x)].st;
		}
	#endif
	
	#ifndef SIMPLE
		vec4 worldcoord = ModelMatrix * mix(parmPosition, aVertex2, uInterpolationFactor);
	#else
		vec4 worldcoord = ModelMatrix * parmPosition;
	#endif

	vec4 eyeCoordPos = ViewMatrix * worldcoord;

	vColor = aColor;

	#ifndef SIMPLE
		pixelpos.xyz = eyeCoordPos.xyz;
		pixelpos.w = -eyeCoordPos.z/eyeCoordPos.w;

		glowdist.x = -((uGlowTopPlane.w + uGlowTopPlane.x * worldcoord.x + uGlowTopPlane.y * worldcoord.z) * uGlowTopPlane.z) - worldcoord.y;
		glowdist.y = worldcoord.y + ((uGlowBottomPlane.w + uGlowBottomPlane.x * worldcoord.x + uGlowBottomPlane.y * worldcoord.z) * uGlowBottomPlane.z);

		if (uSplitBottomPlane.z != 0.0)
		{
			gl_ClipDistance[3] = -((uSplitTopPlane.w + uSplitTopPlane.x * worldcoord.x + uSplitTopPlane.y * worldcoord.z) * uSplitTopPlane.z) - worldcoord.y;
			gl_ClipDistance[4] = worldcoord.y + ((uSplitBottomPlane.w + uSplitBottomPlane.x * worldcoord.x + uSplitBottomPlane.y * worldcoord.z) * uSplitBottomPlane.z);
		}
	#endif
	
	#ifdef SPHEREMAP
		vec3 u = normalize(eyeCoordPos.xyz);
		vec4 n = normalize(TextureMatrix * vec4(parmTexCoord.x, 0.0, parmTexCoord.y, 0.0));	// use texture matrix and coordinates for our normal. Since this is only used on walls, the normal's y coordinate is always 0.
		vec3 r = reflect(u, n.xyz);
		float m = 2.0 * sqrt( r.x*r.x + r.y*r.y + (r.z+1.0)*(r.z+1.0) );
		vec2 sst = vec2(r.x/m + 0.5,  r.y/m + 0.5);
		vTexCoord.xy = sst;
	#else
		vTexCoord = TextureMatrix * vec4(parmTexCoord, 0.0, 1.0);
	#endif
	
	gl_Position = ProjectionMatrix * eyeCoordPos;
		
	if (uClipHeightDirection != 0.0) // clip planes used for reflective flats
	{
		gl_ClipDistance[0] = (worldcoord.y - uClipHeight) * uClipHeightDirection;
	}
	else if (uClipLine.x > -1000000.0) // and for line portals - this will never be active at the same time as the reflective planes clipping so it can use the same hardware clip plane.
	{
		gl_ClipDistance[0] = -( (worldcoord.z - uClipLine.y) * uClipLine.z + (uClipLine.x - worldcoord.x) * uClipLine.w ) + 1.0/32768.0;	// allow a tiny bit of imprecisions for colinear linedefs.
	}

	// clip planes used for translucency splitting
	gl_ClipDistance[1] = worldcoord.y - uClipSplit.x;
	gl_ClipDistance[2] = uClipSplit.y - worldcoord.y;
	
}