#version 150

in vec4 vertColor;
in float vertOffset;
in float vertGray;
in vec2 vertTexCoord;
flat in float vertDark;
out vec4 fragColor;
uniform float depthOffset;
uniform float spacing;
uniform float time;
uniform float slant;
uniform float contrast;

uniform sampler2D colorTexture;

void main() {
	float borderLuminance = step(0.5, mod(gl_FragCoord.x * slant + gl_FragCoord.y + time * 2 * spacing, spacing) / spacing);
	fragColor = vec4(mix(vertColor, vertColor * vec4(vertDark, vertDark, vertDark, 1.0), borderLuminance));
	fragColor += vec4(vertGray);
	fragColor *= texture(colorTexture, vertTexCoord);
	gl_FragDepth = gl_FragCoord.z - depthOffset * vertOffset * gl_FragCoord.w;
}