function applyToImageData(imageData, effect) {
var width = imageData.width;
var height = imageData.height;
var data = imageData.data;
for(var i = 0; i < width * height; i++) {
vec4.set(tmpPixel, data[i*4+0]/255, data[i*4+1]/255, data[i*4+2]/255, data[i*4+3]/255);
applyToPixel(tmpPixel, effect, tmpPixel);
data[i*4+0] = tmpPixel[0]*255;
data[i*4+1] = tmpPixel[1]*255;
data[i*4+2] = tmpPixel[2]*255;
data[i*4+3] = tmpPixel[3]*255;
}
}
CubeGeometry.prototype._closestTile = function(view, level) {
var ray = this._vec;
// Compute a view ray into the central screen point.
vec4.set(ray, 0, 0, 1, 1);
vec4.transformMat4(ray, ray, view.inverseProjection());
var minAngle = Infinity;
var closestFace = null;
// Find the face whose vector makes a minimal angle with the view ray.
// This is the face into which the view ray points.
for (var face in faceVectors) {
var vector = faceVectors[face];
// For a small angle between two normalized vectors, angle ~ 1-cos(angle).
var angle = 1 - vec3.dot(vector, ray);
if (angle < minAngle) {
minAngle = angle;
closestFace = face;
}
}
// Project view ray onto cube, i.e., normalize the coordinate with
// largest absolute value to ±0.5.
var max = Math.max(Math.abs(ray[0]), Math.abs(ray[1]), Math.abs(ray[2])) / 0.5;
for (var i = 0; i < 3; i++) {
ray[i] = ray[i] / max;
}
// Rotate view ray into front face.
var rot = faceRotation[closestFace];
rotateVector(ray, 0, -rot.x, -rot.y);
// Get the desired zoom level.
var tileZ = this.levelList.indexOf(level);
var numX = level.numHorizontalTiles();
var numY = level.numVerticalTiles();
// Find the coordinates of the tile that the view ray points into.
var tileX = clamp(Math.floor((0.5 + ray[0]) * numX), 0, numX - 1);
var tileY = clamp(Math.floor((0.5 - ray[1]) * numY), 0, numY - 1);
return new CubeTile(closestFace, tileX, tileY, tileZ, this);
};