 uniform vec4 uCrevasPointsY[CREVAS_POINTS_MAXN/4];
 uniform vec4 uCrevasUnitVecsX[CREVAS_POINTS_MAXN/4];
 uniform vec4 uCrevasUnitVecsY[CREVAS_POINTS_MAXN/4];
-uniform int  uCrevasPointsN;
 
 varying vec3 vColor;
 varying vec3 vTextureCoord;


vec3 calculateColor(vec2 shift) {
	vec3 color;
	for (int i = 0; i < uParticleN; i++) {
		vec2 p = uParticleCoords[i];
		vec4 pcol = uParticleColors[i];
		float d2 = dot(aCoord - p, aCoord - p);

	vec4 shiftx = vec4(0.0);
	vec4 shifty = vec4(0.0);

	for (int i = 0; i < CREVAS_POINTS_MAXN/4; i++) {
		/*
		There are a point A and a line segment PQ.
		Here, calculating `weight` by following:
