in vec4 uvcoordsvar;

out vec4 FragColor;

uniform sampler2D outlineColor;
uniform sampler2D outlineDepth;

uniform float alpha;
uniform bool doExpand;

void main()
{
	ivec2 uv = ivec2(gl_FragCoord.xy);
	FragColor = texelFetch(outlineColor, uv, 0).rgba;
	float depth = texelFetch(outlineDepth, uv, 0).r;

	vec4 color[4];
	color[0] = texelFetchOffset(outlineColor, uv, 0, ivec2( 1,  0)).rgba;
	color[1] = texelFetchOffset(outlineColor, uv, 0, ivec2( 0,  1)).rgba;
	color[2] = texelFetchOffset(outlineColor, uv, 0, ivec2(-1,  0)).rgba;
	color[3] = texelFetchOffset(outlineColor, uv, 0, ivec2( 0, -1)).rgba;

	vec4 values = vec4(color[0].a, color[1].a, color[2].a, color[3].a);

	bool is_blank_pixel = !(FragColor.a != 0.0 || (depth == 1.0 && !doExpand));
	vec4 tests = vec4(is_blank_pixel);
	tests *= step(vec4(1e-6), values); /* (color.a != 0.0) */
	tests *= (doExpand) ? vec4(1.0) : step(values, vec4(0.999)); /* (doExpand || color.a != 1.0) */
	bvec4 btests = equal(tests, vec4(1.0));

	FragColor = (btests.x) ? color[0] : FragColor;
	FragColor = (btests.y) ? color[1] : FragColor;
	FragColor = (btests.z) ? color[2] : FragColor;
	FragColor = (btests.w) ? color[3] : FragColor;

	FragColor *= (is_blank_pixel) ? alpha : 1.0;
}