shader
shader: string = `uniform vec2 circleCenters[CIRCLE_COUNT];uniform float circleRadii[CIRCLE_COUNT];float circleMinDistance(vec2 target, out float colorIndex) {colorIndex = 2.0;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;}`