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al_orthogr...c_transform(3) Library Functions Manual al_orthogr...c_transform(3) NAME al_orthographic_transform - Allegro 5 API SYNOPSIS #include <allegro5/allegro.h> void al_orthographic_transform(ALLEGRO_TRANSFORM *trans, float left, float top, float n, float right, float bottom, float f) DESCRIPTION Combines the given transformation with an orthographic transformation which maps the screen rectangle to the given left/top and right/bottom coordi- nates. near/far is the z range, coordinates outside of that range will get clipped. Normally -1/1 is fine because all 2D graphics will have a z coor- dinate of 0. However if you for example do al_draw_rectangle(0, 0, 100, 100) and rotate around the x axis ("towards the screen") make sure your z range allows values from -100 to 100 or the rotated rectangle will get clipped. Also, if you are using a depth buffer the z range decides the depth resolu- tion. For example if you have a 16 bit depth buffer there are only 65536 discrete depth values. So if your near/far is set to -1000000/1000000 most of the z positions would not result in separate depth values which could lead to artifacts. The result of applying this transformation to coordinates will be to nor- malize visible coordinates into the cube from -1/-1/-1 to 1/1/1. Such a transformation is mostly useful for passing it to al_use_projection_trans- form(3) - see that function for an example use. SINCE 5.1.3 SEE ALSO al_use_projection_transform(3), al_perspective_transform(3) Allegro reference manual al_orthogr...c_transform(3)
NAME | SYNOPSIS | DESCRIPTION | SINCE | SEE ALSO
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