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This thread is locked; no one can reply to it.
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| Comparing Colors works sometimes |
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InfiniteLoop
Member #8,434
March 2007
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Hello everyone, here is the scenario. Making a 2D platformer, I have my standard background image, and a completely black and white version also loaded into memory. The black and white image is almost completely white, with the platforms themselves being completely black (no gradiant). Every cycle, I am comparing the color on my BW background against the color black to determine if I am standing on the ground. This works, until randomnly my avatar falls through the ground. It seems to be random at any given place and I cannot figure out why. Can you tell me what I am doing wrong? Furthermore, is there a better way to handle platforming? 1int color_equiv(ALLEGRO_COLOR c1, ALLEGRO_COLOR c2) {
2
3 unsigned char r1, g1, b1, r2, g2, b2;
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5 al_unmap_rgb(c1, &r1, &g1, &b1);
6 al_unmap_rgb(c2, &r2, &g2, &b2);
7
8 if (r1 != r2 || g1 != g2 || b1 != b2)
9 return 0;
10 else
11 return 1;
12
13}
14
15//in my update
16if(!color_equiv(al_get_pixel(image, x, tempY + 6), al_map_rgb(0, 0, 0)))
17{
18y = tempY;
19}
The color_equiv function was by another user on these forums. Thanks for your help EDIT: Nevermind, figured it out. The question still stands though whether or not there is a better way to handle this |
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l j
Member #10,584
January 2009
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Why not use tilemaps. Or a list of bounding boxes or maybe a list of polygons? The only game where I can imagine a bitmap to be truly useful for collision detection is a game like worms.
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InfiniteLoop
Member #8,434
March 2007
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I figured tilemaps would not be accurate enough. Also, I figured that collision detection against many, large, bounding boxes would be less efficient that comparing a single point. Finally, I figured using bitmaps would allow for rapid map development. Am I wrong? |
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l j
Member #10,584
January 2009
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Well you could always put bounding boxes in a grid. So you only have to check for boxes close to the entities. Or, although more difficult, you could use a quadtree to put your boxes in. Also comparing to a single point is not going to be very accurate, at all.
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Audric
Member #907
January 2001
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InfiniteLoop said: I figured using bitmaps would allow for rapid map development If you have found the right tools to keep the "map" and the "collision map" synchronized, then it's a good development method. |
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