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#ifdef GL_FRAGMENT_PRECISION_HIGH
precision highp float;
#else
precision mediump float;
#endif
varying vec4 v_color;
varying vec2 v_texcoord;
uniform vec4 colors[LEN];
uniform vec2 size;
uniform float degree;
uniform vec2 grad_box;
uniform vec2 origin;
uniform bool linear;
uniform bool blend;
uniform int count;
vec4 gradient(){
float step;
vec2 normal = (gl_FragCoord.xy - grad_box)/size;
vec2 uv = normal - origin;
float rad = radians(degree);
if(linear){
uv *= vec2(1.0)/vec2(abs(cos(rad)) + abs(sin(rad)));
vec2 rotated = vec2(uv.x * cos(rad) - uv.y * sin(rad) + origin.x,
uv.x * sin(rad) + uv.y * cos(rad) + origin.y);
step = rotated.x;
} else {
vec2 uv = normal - origin;
uv = vec2(uv.x * cos(rad) - uv.y * sin(rad),
uv.x * sin(rad) + uv.y * cos(rad));
uv = vec2(-atan(uv.y, uv.x)/3.14159265 * 0.5 + 0.5, 0.0);
step = uv.x;
}
if(!blend){
float smooth = 1.0/float(count);
int ind = int(step/smooth);
return colors[ind];
}
float smooth = 1.0/float(count - 1);
int ind = int(step/smooth);
float at = float(ind)*smooth;
vec4 color = colors[ind];
if(ind > 0) color = mix(colors[ind - 1], color, smoothstep(at - smooth, at, step));
if(ind <= count - 1) color = mix(color, colors[ind + 1], smoothstep(at, at + smooth, step));
return color;
}
void main(){
gl_FragColor = gradient();
}
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