Add factories for finer color management

src/drawables/shapes/circle-factory.ts

@@ -0,0 +1,61 @@
+import { mat2d, vec2, vec3, vec4 } from 'gl-matrix';
+import { codeForColorAccess } from '../../helper/code-for-color-access';
+import { DrawableDescriptor } from '../drawable-descriptor';
+import { EmptyDrawable } from '../empty-drawable';
+
+/**
+ * @category Drawable
+ */
+class CircleBase extends EmptyDrawable {
+  constructor(public center: vec2, public radius: number) {
+    super();
+  }
+}
+
+/**
+ * @category Drawable
+ */
+export const CircleFactory = (color: vec3 | vec4 | number): typeof CircleBase => {
+  class Circle extends CircleBase {
+    public static descriptor: DrawableDescriptor = {
+      sdf: {
+        shader: `
+            uniform vec2 circleCenters[CIRCLE_COUNT];
+            uniform float circleRadii[CIRCLE_COUNT];
+  
+            float circleMinDistance(vec2 target, out vec4 color) {
+              color = ${codeForColorAccess(color)};
+              float minDistance = 1000.0;
+              for (int i = 0; i < CIRCLE_COUNT; i++) {
+                float dist = distance(circleCenters[i], target) - circleRadii[i];
+                minDistance = min(minDistance, dist);
+              }
+  
+              return minDistance;
+            }
+          `,
+        distanceFunctionName: 'circleMinDistance',
+      },
+      propertyUniformMapping: {
+        center: 'circleCenters',
+        radius: 'circleRadii',
+      },
+      uniformCountMacroName: 'CIRCLE_COUNT',
+      shaderCombinationSteps: [0, 1, 2, 3, 8, 16],
+      empty: new Circle(vec2.create(), 0),
+    };
+
+    public minDistance(target: vec2): number {
+      return vec2.dist(this.center, target) - this.radius;
+    }
+
+    protected getObjectToSerialize(transform2d: mat2d, transform1d: number): any {
+      return {
+        center: vec2.transformMat2d(vec2.create(), this.center, transform2d),
+        radius: this.radius * transform1d,
+      };
+    }
+  }
+
+  return Circle;
+};