ScreenBlit.frag

#version 300 es

precision highp float;
precision highp sampler2D;

in highp vec2 textureUV;

out highp vec4 FragColor;

uniform highp sampler2D rteTexture;
uniform highp sampler2D rteGUITexture;

vec4 texture2DAA(sampler2D tex, vec2 uv) {
	vec2 texsize = vec2(textureSize(tex, 0));
	vec2 uv_texspace = uv * texsize;
	vec2 seam = floor(uv_texspace + .5);
	uv_texspace = (uv_texspace - seam) / fwidth(uv_texspace) + seam;
	uv_texspace = clamp(uv_texspace, seam - .5, seam + .5);
	return texture(tex, uv_texspace / texsize);
}

void main() {
	vec4 guiColor = texture2DAA(rteGUITexture, textureUV);
	float guiSolid = step(0.00000001, guiColor.r + guiColor.g + guiColor.b);
	float blendRatio = max(guiColor.a, guiSolid);
	FragColor = (texture2DAA(rteTexture, textureUV) * (1.0F - blendRatio)) + guiColor * blendRatio;
}