在OpenGL ES中正确转换位置

Question

I'm attempting to move a simple OpenGL Triangle rendered in android to the touch location.

I can only seem to get the triangle moving along in a grid sort of fashion. This is because despite my best efforts I am increasing X and Y coordinates by the same amount. I've attempted to use a sort of normalised value to alter the rate of movement so that either the X or Y change depending on which (X or Y) is closer to the target location, however this was to no avail. I'm wondering what it is I am missing and wondered if anyone can help as I am out of ideas as to how to get this to work.

Answer 1

PointF vector = new PointF();

vector.x = destination.getX() - origin.getX();
vector.y = destination.getY() - origin.getY();

float length = (float)Math.sqrt(vector.x * vector.x + vector.y * vector.y);

// Normalize
vector.x /= length;
vector.y /= length;

// when you move your rectangle:

PointF newPosition = new PointF();
newPosition.x = currentPosition.x + (millisecSinceLastAnimationTick / 1000f) * amountToMovePerSecond * vector.x;
newPosition.y = currentPosition.y + (millisecSinceLastAnimationTick / 1000f) * amountToMovePerSecond * vector.y;

glTranslate(newPosition.x, newPosition.y, 0);

currentPosition.set(newPosition);

This should get you started.