NAME¶
get_camera_matrix - Constructs a camera matrix for perspective projection.
Allegro game programming library.
SYNOPSIS¶
#include <allegro.h>
void get_camera_matrix(MATRIX *m, fixed x, y, z, xfront, yfront, zfront,
fixed xup, yup, zup, fov, aspect);
DESCRIPTION¶
Constructs a camera matrix for translating world-space objects into a normalised
view space, ready for the perspective projection. The x, y, and z parameters
specify the camera position, xfront, yfront, and zfront are the 'in front'
vector specifying which way the camera is facing (this can be any length:
normalisation is not required), and xup, yup, and zup are the 'up' direction
vector.
The fov parameter specifies the field of view (ie. width of the camera focus) in
binary, 256 degrees to the circle format. For typical projections, a field of
view in the region 32-48 will work well. 64 (90\(de) applies no extra scaling
- so something which is one unit away from the viewer will be directly scaled
to the viewport. A bigger FOV moves you closer to the viewing plane, so more
objects will appear. A smaller FOV moves you away from the viewing plane,
which means you see a smaller part of the world.
Finally, the aspect ratio is used to scale the Y dimensions of the image
relative to the X axis, so you can use it to adjust the proportions of the
output image (set it to 1 for no scaling - but keep in mind that the
projection also performs scaling according to the viewport size). Typically,
you will pass (float)w/(float)h, where w and h are the parameters you passed
to set_projection_viewport.
Note that versions prior to 4.1.0 multiplied this aspect ratio by 4/3.
SEE ALSO¶
apply_matrix(3alleg4),
get_align_matrix(3alleg4),
set_projection_viewport(3alleg4),
persp_project(3alleg4)