#version 150

in vec3 position;
in vec4 color;
in float texCoord;

uniform mat4 projectionTransform;
uniform mat4 viewTransform;
uniform mat4 modelTransform;
uniform float time;
uniform float shimmerStrength;

out vec4 vertColor;
out float vertTexCoord;

float hueMix(float hue, float center) {
	hue = mod(hue - center + 3.0, 6.0);
	return min(hue, 1.0) - max(0.0, min(1.0, hue - 3.0));
}

vec4 colorWithHue(float hue) {
	vec4 color;
	color.r = hueMix(hue, 0.0);
	color.g = hueMix(hue, 2.0);
	color.b = hueMix(hue, 4.0);
	color.a = 1.0;
	return color;
}

void main() {
	vertColor = mix(color, colorWithHue(time), shimmerStrength * 0.25);
	vertTexCoord = texCoord - fract(time);
	gl_Position = projectionTransform * viewTransform * modelTransform * vec4(position, 1.0);
}