So, I am working on a 2d tower defense game and need the enemy's sprite to rotate whenever they change direction. I understand this can be done easily using built-in java rotate/affine transform methods, but for the sake of optimization/performance, I want to know whether it's possible to do the rotation with an array of pixels instead.
thanks
GayLord, I'm not sure if you're still looking for an answer here but for the sake of other members, here is what I was able to use to solve a similar problem. I've been building a game engine that utilizes a similar graphical structure to what you are describing. The rotation function I use is this: All of the floats could be replaced by doubles and work perhaps better. I used floats to help with performance on lower end computers.
float cos = (float)Math.cos(-angle);//The angle you are rotating (in radians)
float sin = (float)Math.sin(-angle);//The angle you are rotating (in radians)
float sWidth = screenWidth/2;
float sHeight = screenHeight/2;
float pWidth = pixelArrayWidth/2;
float pHeight = pixelArrayHeight/2;
for each pixel in screen{
int xPosition = pixelIndexX - sWidth;
int yPosition = pixelIndexY - sHeight;
int tx = (int)(xPosition * cos - yPosition * sin);
int ty = (int)(xPosition * sin + yPosition * cos);
xPosition = tx + pWidth;
yPosition = ty + pHeight;
if((xPosition is out of bounds) or (yPosition is out of bounds)) continue;
setPixelAt(screenPixelX, screenPixelY, pixelArray[xPosition + yPosition * pixelArrayWidth] )
}
I know that it is patchy with psuedo code and java code but it should be understandable. If anyone needs some clarification just comment and ask about it.
