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.. default-domain:: C
Project / UnProject
================================================================================
Header: cglm/project.h
Viewport is required as *vec4* **[X, Y, Width, Height]** but this doesn't mean
that you should store it as **vec4**. You can convert your data representation
to vec4 before passing it to related functions.
Table of contents (click to go):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Functions:
1. :c:func:`glm_unprojecti`
#. :c:func:`glm_unproject`
#. :c:func:`glm_project`
Functions documentation
~~~~~~~~~~~~~~~~~~~~~~~
.. c:function:: void glm_unprojecti(vec3 pos, mat4 invMat, vec4 vp, vec3 dest)
| maps the specified viewport coordinates into specified space [1]
the matrix should contain projection matrix.
if you don't have ( and don't want to have ) an inverse matrix then use
glm_unproject version. You may use existing inverse of matrix in somewhere
else, this is why glm_unprojecti exists to save save inversion cost
[1] space:
- if m = invProj: View Space
- if m = invViewProj: World Space
- if m = invMVP: Object Space
You probably want to map the coordinates into object space
so use invMVP as m
Computing viewProj:
.. code-block:: c
glm_mat4_mul(proj, view, viewProj);
glm_mat4_mul(viewProj, model, MVP);
glm_mat4_inv(viewProj, invMVP);
Parameters:
| *[in]* **pos** point/position in viewport coordinates
| *[in]* **invMat** matrix (see brief)
| *[in]* **vp** viewport as [x, y, width, height]
| *[out]* **dest** unprojected coordinates
.. c:function:: void glm_unproject(vec3 pos, mat4 m, vec4 vp, vec3 dest)
| maps the specified viewport coordinates into specified space [1]
the matrix should contain projection matrix.
this is same as glm_unprojecti except this function get inverse matrix for
you.
[1] space:
- if m = proj: View Space
- if m = viewProj: World Space
- if m = MVP: Object Space
You probably want to map the coordinates into object space so use MVP as m
Computing viewProj and MVP:
.. code-block:: c
glm_mat4_mul(proj, view, viewProj);
glm_mat4_mul(viewProj, model, MVP);
Parameters:
| *[in]* **pos** point/position in viewport coordinates
| *[in]* **m** matrix (see brief)
| *[in]* **vp** viewport as [x, y, width, height]
| *[out]* **dest** unprojected coordinates
.. c:function:: void glm_project(vec3 pos, mat4 m, vec4 vp, vec3 dest)
| map object coordinates to window coordinates
Computing MVP:
.. code-block:: c
glm_mat4_mul(proj, view, viewProj);
glm_mat4_mul(viewProj, model, MVP);
this could be useful for gettng a bbox which fits with view frustum and
object bounding boxes. In this case you crop view frustum box with objects
box
Parameters:
| *[in]* **pos** object coordinates
| *[in]* **m** MVP matrix
| *[in]* **vp** viewport as [x, y, width, height]
| *[out]* **dest** projected coordinates
|
