private void findMinMaxX(int y) {
		xMin = Integer.MAX_VALUE;
		xMax = Integer.MIN_VALUE;
		for (int i = rasterCount; --i >= 0;) {
			if (yRaster[i] == y) {
				int x = xRaster[i];
				if (x < xMin) {
					xMin = x;
					zXMin = zRaster[i];
				}
				if (x > xMax) {
					xMax = x;
					zXMax = zRaster[i];
				}
			}
			if (yRaster[i] == -y) { // 0 will run through here too
				int x = -xRaster[i];
				if (x < xMin) {
					xMin = x;
					zXMin = -zRaster[i];
				}
				if (x > xMax) {
					xMax = x;
					zXMax = -zRaster[i];
				}
			}
		}
	}