Pixel perfect collision detection?

Newbie & Debugging Questions
#1

This is something i need for my game as collision detection is not as accurtate as it needs to be… so, do you guys have any idea how to do this? I do not … :’(

#2

2 topics alone on the first page of the Game Mechanics board.

http://www.java-gaming.org/topics/perfect-colision-system-in-lwjgl/27836/view.html

#3

Im not using the LWJGL since im on android
and the other one does not have an actual answer

#4

There are many different solutions suited for many different situations. Could you link to a screenshot explaining what you’re dealing with?

There’s the brute force method, but it is rarely good on its own. Then you’d use quad-trees as a broad-phase tester.
But if you have a simple platformer, you could make do with bitmasks, or even just have an array of ints representing the y-height of each x-width in each ground-tile.

#5

how do i post images? i only see an option by linking it to a website

#6

The first link has a post (by yours truly) at the bottom of the thread detailing how one goes about implementing pixel-perfect collision. The second link contains a simple method for basic collision detection in games. The basics behind 2D pixel-perfect collision detection methods don’t exactly change from engine to engine.

#7

Ok so after reviewing your thread i noticed this code

public static boolean intersectsByte(byte[][] a1, byte[][] a2, int x, int y) {
    for (int i = 0; i < a1.length; i++) {
        for (int j = 0; j < a1[0].length; j++) {
            if (a1[i][j] == 1) {
                for (int k = 0; k < a1.length; k++) {
                    for (int l = 0; l < a1[0].length; l++) {
                        if (((k - x) >= 0) && ((k - x) < a2.length) && ((l - y) >= 0) && ((l - y) < a2[0].length)) {
                            if (a2[k - x][l - y] == 1) {
                                return true; } } } } } } }
    return false; }

I need some help understanding this however. If i already have two bitmaps setup how to I use this code to detect pixel perfect collision.?

#8

One method that would work would be to simply convert both of your images to byte[][] arrays, where 1 represents an opaque pixel and 0 represents a transparent pixel. That may not be the best method, though.