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al_transfo...projective(3) Library Functions Manual al_transfo...projective(3) NAME al_transform_coordinates_3d_projective - Allegro 5 API SYNOPSIS #include <allegro5/allegro.h> void al_transform_coordinates_3d_projective(const ALLEGRO_TRANSFORM *trans, float *x, float *y, float *z) DESCRIPTION Transform x, y, z as homogeneous coordinates. This is the same as us- ing al_transform_coordinates_4d(3) with the w coordinate set to 1, then dividing x, y, z by the resulting w. This will provide the same nor- malized coordinates Allegro will draw to when a projective transform is in effect as set with al_use_projection_transform(3). To get the ac- tual pixel coordinates from those translate and scale like so (w and h would be the pixel dimensions of the target bitmap): x = w / 2 + x * w / 2 y = h / 2 - y * h / 2 Parameters: • trans - Transformation to use • x, y, z - Pointers to the coordinates Example: ALLEGRO_TRANSFORM t2; al_copy_transform(&t2, al_get_current_transform()); al_compose_transform(&t2, al_get_current_projection_transform()); ALLEGRO_TRANSFORM t3; al_identity_transform(&t3); al_scale_transform(&t3, 0.5, -0.5); al_translate_transform(&t3, 0.5, 0.5); al_scale_transform(&t3, al_get_bitmap_width(al_get_target_bitmap()), al_get_bitmap_height(al_get_target_bitmap())); al_transform_coordinates_3d_projective(&t2, &x, &y, &z); // x, y now contain normalized coordinates al_transform_coordinates(&t3, &x, &y); // x, y now contain pixel coordinates Since 5.2.4 SEE ALSO al_use_transform(3), al_transform_coordinates(3), al_transform_coordi- nates_3d(3), al_use_projection_transform(3) Allegro reference manual al_transfo...projective(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO
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