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| How can I map mouse coordinates to world coordinates using allegro transofrms? |
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Bungow
Member #16,693
June 2017
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Hello, in first place sorry for my bad english and thanks for your time. I have a 2d tiled base project, and is drawed to screen using this allegro transform: 1mkLevel *level = ctx->current_level;
2 ALLEGRO_MOUSE_STATE mouse;
3 al_get_mouse_state(&mouse);
4
5 float world_x =
6 -(((ctx->screen.width / 2) - mouse.x) - level->viewport.x);
7 float world_y =
8 -(((ctx->screen.height / 2) - mouse.y) - level->viewport.y);
9
10 al_identity_transform(&level->viewport.transform);
11
12 al_translate_transform(&level->viewport.transform, -level->viewport.x,
13 -level->viewport.y);
14
15 al_rotate_transform(&level->viewport.transform, level->viewport.rotate);
16 al_scale_transform(&level->viewport.transform, level->viewport.zoom,
17 level->viewport.zoom);
18
19 al_translate_transform(&level->viewport.transform,
20 ctx->screen.width * 0.5,
21 ctx->screen.height * 0.5);
22
23 //al_transform_coordinates(&level->viewport.transform, &world_x,
24 // &world_y);
25
26
27 al_use_transform(&level->viewport.transform);
28 /* DRAW START HERE */
How can I use this transform to translate my mouse position to world position? I tried to use al_transform_cordinates but I'm not sure how I have to treath the mouse value before passing to it. My current implementation of world_x and world_y only works before zoom or rotation are applied |
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SiegeLord
Member #7,827
October 2006
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al_invert_transform(&level->viewport.transform); al_transform_coordinates(&level->viewport.transform, &mouse_x, &mouse_y); That should work. Obviously it might make sense for you to copy the transformation before inverting it. "For in much wisdom is much grief: and he that increases knowledge increases sorrow."-Ecclesiastes 1:18 |
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Bungow
Member #16,693
June 2017
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Thanks! |
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