package org.openrndr.extra.shadestyles

import org.openrndr.color.ColorRGBa
import org.openrndr.draw.ShadeStyle
import org.openrndr.extra.parameters.ColorParameter
import org.openrndr.extra.parameters.Description
import org.openrndr.extra.parameters.DoubleParameter
import org.openrndr.math.Vector2

@Description("Half-angular gradient")
class HalfAngularGradient(color0: ColorRGBa, color1: ColorRGBa, offset: Vector2 = Vector2.ZERO, rotation: Double = 0.0) : ShadeStyle() {
    @ColorParameter("start color", order = 0)
    var color0: ColorRGBa by Parameter()
    @ColorParameter("end color", order = 1)
    var color1: ColorRGBa by Parameter()
    var offset: Vector2 by Parameter()
    @DoubleParameter("rotation", -180.0, 180.0, order = 2)
    var rotation: Double by Parameter()
    @DoubleParameter("length", 0.0, 10.0, order = 3)
    var length: Double by Parameter()

    init {
        this.color0 = color0
        this.color1 = color1
        this.offset = offset
        this.rotation = rotation
        this.length = length

        fragmentTransform = """
            vec2 coord = (c_boundsPosition.xy - vec2(0.5) + p_offset/2.0) * 2.0;
            
            float cr = cos(radians(p_rotation));
            float sr = sin(radians(p_rotation));
            mat2 rm = mat2(cr, -sr, sr, cr);
            vec2 rc = rm * coord;
            float f = abs(atan(rc.y, rc.x)) / (3.1415926536);
            
            //float f = abs(atan(rc.y/rc.x))  / (3.1415926536/2.0);
            //float f = (atan(rc.y/rc.x) + 3.1415926536/2.0) / (3.1415926536);            
                   
            vec4 color0 = p_color0 * vec4(p_color0.aaa, 1.0);
            vec4 color1 = p_color1 * vec4(p_color1.aaa, 1.0);
                       
            vec4 gradient = color0 * (1.0-f) + color1 * f;
            vec4 fn = vec4(x_fill.rgb, 1.0) * x_fill.a;            
            x_fill = fn * gradient;
            if (x_fill.a !=0) {
                x_fill.rgb /= x_fill.a;
            }        
    }
    """
    }
}

fun halfAngularGradient(color0: ColorRGBa, color1: ColorRGBa, offset: Vector2 = Vector2.ZERO, rotation: Double = 0.0): ShadeStyle {
    return HalfAngularGradient(color0, color1, offset, rotation)
}