in vec2 Texcoord;
in vec4 Color;

uniform sampler2D tex;
uniform sampler2D texZBuf;
uniform UBOOL textured;
uniform UBOOL hasZBuffer;
uniform vec2 texcropZBuf;
uniform vec2 screenSize;
uniform float alphaRef;

const float offsetY = 0.0;

OUTPUT

void checkZBuffer() {
	vec2 zCoord = vec2((gl_FragCoord.x - 0.5) / screenSize.x, 1.0 - (gl_FragCoord.y - offsetY - 0.5) / screenSize.y);
	vec2 sampled = texture(texZBuf, zCoord * texcropZBuf).ra;
	float sceneZ = sampled.y + sampled.x / 256.0;

	if (gl_FragCoord.z * 1.0039 > sceneZ)
		discard;
}

void main() {
	if (UBOOL_TEST(hasZBuffer))
		checkZBuffer();
	outColor = Color;
	if (UBOOL_TEST(textured)) {
		outColor *= texture(tex, Texcoord);
	}

	if (outColor.a < alphaRef)
		discard;
}