Collision between sprites in game programming?
- by Lyn Maxino
I've since just started coding for an android game using eclipse. I've read Beginning Android Game Programming and various other e-books. Recently, I've encountered a problem with collision between sprites. I've used this code template for my program.
package com.project.CAI_test;
import java.util.Random;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Rect;
public class Sprite {
// direction = 0 up, 1 left, 2 down, 3 right,
// animation = 3 back, 1 left, 0 front, 2 right
int[] DIRECTION_TO_ANIMATION_MAP = { 3, 1, 0, 2 };
private static final int BMP_ROWS = 4;
private static final int BMP_COLUMNS = 3;
private static final int MAX_SPEED = 5;
private GameView gameView;
private Bitmap bmp;
private int x = 0;
private int y = 0;
private int xSpeed;
private int ySpeed;
private int currentFrame = 0;
private int width;
private int height;
public Sprite(GameView gameView, Bitmap bmp) {
this.width = bmp.getWidth() / BMP_COLUMNS;
this.height = bmp.getHeight() / BMP_ROWS;
this.gameView = gameView;
this.bmp = bmp;
Random rnd = new Random();
x = rnd.nextInt(gameView.getWidth() - width);
y = rnd.nextInt(gameView.getHeight() - height);
xSpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED;
ySpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED;
}
private void update() {
if (x >= gameView.getWidth() - width - xSpeed || x + xSpeed <= 0) {
xSpeed = -xSpeed;
}
x = x + xSpeed;
if (y >= gameView.getHeight() - height - ySpeed || y + ySpeed <= 0) {
ySpeed = -ySpeed;
}
y = y + ySpeed;
currentFrame = ++currentFrame % BMP_COLUMNS;
}
public void onDraw(Canvas canvas) {
update();
int srcX = currentFrame * width;
int srcY = getAnimationRow() * height;
Rect src = new Rect(srcX, srcY, srcX + width, srcY + height);
Rect dst = new Rect(x, y, x + width, y + height);
canvas.drawBitmap(bmp, src, dst, null);
}
private int getAnimationRow() {
double dirDouble = (Math.atan2(xSpeed, ySpeed) / (Math.PI / 2) + 2);
int direction = (int) Math.round(dirDouble) % BMP_ROWS;
return DIRECTION_TO_ANIMATION_MAP[direction];
}
public boolean isCollition(float x2, float y2) {
return x2 > x && x2 < x + width && y2 > y && y2 < y + height;
}
}
The above code only detects collision between the generated sprites and the surface border. What I want to achieve is a collision detection that is controlled by the update function without having to change much of the coding. Probably several lines placed in the update() function. Tnx for any comment/suggestion.
