Map color collision problem

Question

Hello i'm doing a game in WPF, 2D version (top view)

I have the map and i'm trying to check for color collision in pixel each time the timer is activated

Well...with 1 object it works fine but with more objects at same time it just slow down the process

This is my code every time the dispatchertimer activates and i loop to check for collision on every object

CroppedBitmap cb = new CroppedBitmap(source, new Int32Rect(x, y, 1, 1));
int px = 1 * (source.Format.BitsPerPixel / 8);
byte[] pixels = new byte[px * 1];
cb.CopyPixels(pixels, px, 0);
Color c = Color.FromArgb(pixels[3], pixels[2], pixels[1], pixels[0]);
if (c.R == 255 && c.B == 255 && c.G == 255) {
   pixels = null;
   return true;
}

Any help to simplify the process? I really want to do it in WPF

PS: The map is 1018x731

bummzack · Accepted Answer · 2013-12-09 14:55:37Z

0

I think your main problem here is that you continuously allocate new memory. Instead of creating small buffers for each pixel you want to read, why not create a buffer from all the image pixels and the read directly from there?

Here's how I would modify your code. Disclaimer: I've never used WPF before, so take this with a grain of salt. I don't know how the pixel data is ordered in the array etc.

// -- Don't do this inside the loop, but somewhere else 
// and keep a pointer to the pixels array
// read the entire image into a buffer
CroppedBitmap cb = new CroppedBitmap(source, new Int32Rect(0, 0, 1018, 731));
int px = 1018 * 731 * (source.Format.BitsPerPixel / 8);
byte[] pixels = new byte[px];
cb.CopyPixels(pixels, px, 0);

// -- do this inside your loop
// calculate the offset into the array
int offset = (y * 1018 + x) * 4;
Color c = Color.FromArgb(
    pixels[offset + 3], pixels[offset + 2], pixels[offset + 1], pixels[offset]);

if (c.R == 255 && c.B == 255 && c.G == 255) {
   pixels = null;
   return true;
}

answered Dec 9, 2013 at 14:55

bummzack

22.7k5 gold badges64 silver badges87 bronze badges

\$\begingroup\$ Thanks a lot it worked. The only problem is that the offset throws a exception but i will take care of it, apart of that is awesome :) Well i have one other question, Is appropriate to loop for 51 items and check the collision for each one? Is there any alternative? Because I already did the dumb test and the application don't move :P Well, i'm just new at game development (graphical interface) \$\endgroup\$

GameDev
– GameDev

2013-12-09 21:53:39 +00:00
Commented Dec 9, 2013 at 21:53
\$\begingroup\$ @GameDev checking 51 items per update should not be a problem. But that really depends on what your check actually does... Just implement it and if it's slow, then profile it to find the problem. That's all the advice I can give you. \$\endgroup\$

bummzack
– bummzack

2013-12-09 23:10:27 +00:00
Commented Dec 9, 2013 at 23:10
\$\begingroup\$ should the problem be wpf and to not be a good plataform to develop such a game or it's programming problems like above? \$\endgroup\$

GameDev
– GameDev

2013-12-09 23:11:39 +00:00
Commented Dec 9, 2013 at 23:11

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