[orx-shade-styles] convert to MPP

orx-shade-styles/src/commonMain/kotlin/NPointRadialGradient.kt

@@ -0,0 +1,63 @@
+package org.openrndr.extra.shadestyles
+
+import org.openrndr.color.ColorRGBa
+import org.openrndr.draw.ShadeStyle
+import org.openrndr.extra.parameters.Description
+import org.openrndr.math.Vector2
+
+@Description("Multicolor radial gradient")
+class NPointRadialGradient(
+        colors: Array<ColorRGBa>,
+        points: Array<Double> = Array(colors.size) { it / (colors.size - 1.0) },
+        offset: Vector2 = Vector2.ZERO,
+        rotation: Double = 0.0,
+        length: Double = 1.0) : ShadeStyle()
+
+
+{
+
+    var colors: Array<ColorRGBa> by Parameter()
+
+    // Sorted normalized values defining relative positions of colors
+    var points: Array<Double> by Parameter()
+    var offset: Vector2 by Parameter()
+    var rotation: Double by Parameter()
+    var length: Double by Parameter()
+
+    init {
+        this.colors = colors
+        this.points = points
+        this.offset = offset
+        this.rotation = rotation
+        this.length = length
+
+        fragmentTransform = """
+            vec2 coord = (c_boundsPosition.xy - 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 = clamp(p_length * length(rc), 0.0, 1.0);            
+
+            int i=0;
+            while(i < p_points_SIZE - 1 && f >= p_points[i+1]) { i++; }
+
+            vec4 color0 = p_colors[i];
+            color0.rgb *= color0.a;
+
+            vec4 color1 = p_colors[i+1]; 
+            color1.rgb *= color1.a;
+
+            float g = (f - p_points[i]) / (p_points[i+1] - p_points[i]);
+            vec4 gradient = mix(color0, color1, clamp(g, 0.0, 1.0)); 
+            
+            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;
+            }
+        """
+    }
+}