#version 150

uniform int curveType;
uniform float flatWidth;

in vec2 vertTexCoord;
in vec4 vertColor;

out vec4 fragColor;

#define CURVE_TYPE_LINEAR  0
#define CURVE_TYPE_CONVEX  1
#define CURVE_TYPE_CONCAVE 2
#define CURVE_TYPE_SMOOTH  3
#define M_PI 3.14159265358979323846

float sampleFunction(float position) {
	if (position < 0.0) {
		return 0.0;
	}
	if (position > 1.0) {
		return 1.0;
	}
	if (curveType == CURVE_TYPE_LINEAR) {
		return position;
	}
	if (curveType == CURVE_TYPE_CONVEX) {
		return sin(position * M_PI * 0.5);
	}
	if (curveType == CURVE_TYPE_CONCAVE) {
		return 1.0 - cos(position * M_PI * 0.5);
	}
	if (curveType == CURVE_TYPE_SMOOTH) {
		return 0.5 * sin(M_PI * (position - 0.5)) + 0.5;
	}
	return 0.0;
}

void main() {
	float distance = sqrt(vertTexCoord.x * vertTexCoord.x + vertTexCoord.y * vertTexCoord.y);
	distance = (distance - flatWidth) / (1.0 - flatWidth);
	float curveSample = sampleFunction(1.0 - distance);
	fragColor = vertColor * curveSample;
}