intersect/collision with bitmap and rectangles

Question

I've been trying to write code when the coordinates cx/cy intersect with a rectangle/s the rectangle changes color. This has been driving me up the wall. Here is my code for the rectangles.

for(int k = 0; k<=15; k++){
        k = k * 55;
        for(int i=0;i<=9;i++){
             i = i*55;  
             bounds.set(left+i,top+k,right+i,bottom+k);
             paint.setColor(Color.WHITE);
             canvas.drawRect(bounds, paint);
             if (cx == left || cx == right || cy==top|| cy == bottom){
                 paint.setColor(Color.DKGRAY);
                 canvas.drawRect(bounds, paint);
             }
             i=i/55;
            }    
        k = k/55;
    }

You could use the Rectangle class like this: Rectangle r1 = new Rectangle(x, y, width, height); ... if(r1.intersects(r2)).... — Bene, Nov 30 '14 at 23:35

Andrew Shepherd · Accepted Answer · 2014-12-01T00:30:03.530

Are you trying to inflate a rectangle, and change color when the intersection occurs?

Note that the values of left, right, top and bottom never actually change, so the if the check doesn't trigger in the first iteration of the loop, it never will.

Also, note that, in the case where it does intersect, it will set the color to DKGRAY, but then set it straight back to WHITE again on the next loop. Is this what you want?

I think you mean to do something like this. Here, we are comparing with the actual changing values.

for(int k = 0; k<=15; k++){
    k = k * 55;
    for(int i=0;i<=9;i++){
         i = i*55;  
         int boundsLeft = left + i;
         int boundsTop = top + k;
         int boundsRight = right + i;
         int boundsBottom = bottom + k;
         bounds.set(boundsLeft, boundsTop, boundsRight, boundsBottom);
         paint.setColor(Color.WHITE);
         canvas.drawRect(bounds, paint);
         if (cx == boundsLeft|| cx == boundsRight || cy==boundsTop || cy == boundsBottom ){
             paint.setColor(Color.DKGRAY);
             canvas.drawRect(bounds, paint);
         }
         i=i/55;
        }    
    k = k/55;
}

I would like it to be a permanent rectangle by rectangle change. This is great input, it now runs row by row or column by column. If it runs left or right it changes the color change an entire column if it goes top to bottom it changes the color of the row to Dark Grey. — Mag, Dec 01 '14 at 05:12

score 0 · Answer 2 · answered Dec 02 '14 at 22:13

             for(int i=0;i<=9;i++){
             i = i*55;  
             int boundsLeft = left + i;
             int boundsTop = top + k;
             int boundsRight = right + i;
             int boundsBottom = bottom + k;
             bounds.set(boundsLeft, boundsTop, boundsRight, boundsBottom);
             if(boxes[k][i]==0){
                 paint.setColor(Color.GREEN);
                 canvas.drawRect(bounds, paint);
             }
             else{
                 paint.setColor(Color.DKGRAY);
                 canvas.drawRect(bounds, paint);
             }
             if (cx >= boundsLeft && cx <= boundsRight && cy>=boundsTop && cy <= boundsBottom ){
                 plow.set(boundsLeft, boundsTop, boundsRight, boundsBottom);
                 paint.setColor(Color.DKGRAY);
                 canvas.drawRect(plow, paint);
                 boxes[k][i]=1;
             }
              i=i/55;

            }

intersect/collision with bitmap and rectangles

2 Answers2