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cglm/docs/source/cam.rst
Recep Aslantas 83d5b2c973 docs: add infinite perspective
2026-02-10 22:59:46 +03:00

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.. default-domain:: C
camera
======
Header: cglm/cam.h
There are many convenient functions for camera. For instance :c:func:`glm_look`
is just wrapper for :c:func:`glm_lookat`. Sometimes you only have direction
instead of target, so that makes easy to build view matrix using direction.
There is also :c:func:`glm_look_anyup` function which can help build view matrix
without providing UP axis. It uses :c:func:`glm_vec3_ortho` to get a UP axis and
builds view matrix.
You can also *_default* versions of ortho and perspective to build projection
fast if you don't care specific projection values.
*_decomp* means decompose; these function can help to decompose projection
matrices.
.. note:: Be careful when working with high range (very small near, very large
far) projection matrices. You may not get exact value you gave.
**float** type cannot store very high precision so you will lose precision.
Also your projection matrix will be inaccurate due to losing precision
Table of contents (click to go):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Functions:
1. :c:func:`glm_frustum`
#. :c:func:`glm_ortho`
#. :c:func:`glm_ortho_aabb`
#. :c:func:`glm_ortho_aabb_p`
#. :c:func:`glm_ortho_aabb_pz`
#. :c:func:`glm_ortho_default`
#. :c:func:`glm_ortho_default_s`
#. :c:func:`glm_perspective`
#. :c:func:`glm_perspective_infinite`
#. :c:func:`glm_persp_move_far`
#. :c:func:`glm_perspective_default`
#. :c:func:`glm_perspective_default_infinite`
#. :c:func:`glm_perspective_resize`
#. :c:func:`glm_lookat`
#. :c:func:`glm_look`
#. :c:func:`glm_look_anyup`
#. :c:func:`glm_persp_decomp`
#. :c:func:`glm_persp_decompv`
#. :c:func:`glm_persp_decomp_x`
#. :c:func:`glm_persp_decomp_y`
#. :c:func:`glm_persp_decomp_z`
#. :c:func:`glm_persp_decomp_far`
#. :c:func:`glm_persp_decomp_near`
#. :c:func:`glm_persp_fovy`
#. :c:func:`glm_persp_aspect`
#. :c:func:`glm_persp_sizes`
Functions documentation
~~~~~~~~~~~~~~~~~~~~~~~
.. c:function:: void glm_frustum(float left, float right, float bottom, float top, float nearVal, float farVal, mat4 dest)
| set up perspective peprojection matrix
Parameters:
| *[in]* **left** viewport.left
| *[in]* **right** viewport.right
| *[in]* **bottom** viewport.bottom
| *[in]* **top** viewport.top
| *[in]* **nearVal** near clipping plane
| *[in]* **farVal** far clipping plane
| *[out]* **dest** result matrix
.. c:function:: void glm_ortho(float left, float right, float bottom, float top, float nearVal, float farVal, mat4 dest)
| set up orthographic projection matrix
Parameters:
| *[in]* **left** viewport.left
| *[in]* **right** viewport.right
| *[in]* **bottom** viewport.bottom
| *[in]* **top** viewport.top
| *[in]* **nearVal** near clipping plane
| *[in]* **farVal** far clipping plane
| *[out]* **dest** result matrix
.. c:function:: void glm_ortho_aabb(vec3 box[2], mat4 dest)
| set up orthographic projection matrix using bounding box
| bounding box (AABB) must be in view space
Parameters:
| *[in]* **box** AABB
| *[in]* **dest** result matrix
.. c:function:: void glm_ortho_aabb_p(vec3 box[2], float padding, mat4 dest)
| set up orthographic projection matrix using bounding box
| bounding box (AABB) must be in view space
this version adds padding to box
Parameters:
| *[in]* **box** AABB
| *[in]* **padding** padding
| *[out]* **dest** result matrix
.. c:function:: void glm_ortho_aabb_pz(vec3 box[2], float padding, mat4 dest)
| set up orthographic projection matrix using bounding box
| bounding box (AABB) must be in view space
this version adds Z padding to box
Parameters:
| *[in]* **box** AABB
| *[in]* **padding** padding for near and far
| *[out]* **dest** result matrix
Returns:
square of norm / magnitude
.. c:function:: void glm_ortho_default(float aspect, mat4 dest)
| set up unit orthographic projection matrix
Parameters:
| *[in]* **aspect** aspect ration ( width / height )
| *[out]* **dest** result matrix
.. c:function:: void glm_ortho_default_s(float aspect, float size, mat4 dest)
| set up orthographic projection matrix with given CUBE size
Parameters:
| *[in]* **aspect** aspect ration ( width / height )
| *[in]* **size** cube size
| *[out]* **dest** result matrix
.. c:function:: void glm_perspective(float fovy, float aspect, float nearVal, float farVal, mat4 dest)
| set up perspective projection matrix
Parameters:
| *[in]* **fovy** field of view angle (in radians)
| *[in]* **aspect** aspect ratio ( width / height )
| *[in]* **nearVal** near clipping plane
| *[in]* **farVal** far clipping planes
| *[out]* **dest** result matrix
.. c:function:: void glm_perspective_infinite(float fovy, float aspect, float nearZ, mat4 dest)
| set up perspective projection matrix with infinite far plane
The far clipping plane is pushed to infinity. This can improve depth
precision for distant objects and is required by some rendering techniques
such as shadow volumes. Dispatches to the appropriate clipspace variant
based on compile-time configuration (LH/RH, NO/ZO).
Parameters:
| *[in]* **fovy** field of view angle (in radians)
| *[in]* **aspect** aspect ratio ( width / height )
| *[in]* **nearZ** near clipping plane
| *[out]* **dest** result matrix
.. c:function:: void glm_persp_move_far(mat4 proj, float deltaFar)
| extend perspective projection matrix's far distance
| this function does not guarantee far >= near, be aware of that!
Parameters:
| *[in, out]* **proj** projection matrix to extend
| *[in]* **deltaFar** distance from existing far (negative to shink)
.. c:function:: void glm_perspective_default(float aspect, mat4 dest)
| set up perspective projection matrix with default near/far
and angle values
Parameters:
| *[in]* **aspect** aspect aspect ratio ( width / height )
| *[out]* **dest** result matrix
.. c:function:: void glm_perspective_default_infinite(float aspect, mat4 dest)
| set up infinite perspective projection matrix with default near
and angle values
Equivalent to calling :c:func:`glm_perspective_infinite` with
``fovy = GLM_PI_4`` (45°) and ``nearZ = 0.01``. Useful as a
quick drop-in when you need an infinite projection without tuning
the individual parameters.
Parameters:
| *[in]* **aspect** aspect ratio ( width / height )
| *[out]* **dest** result matrix
.. c:function:: void glm_perspective_resize(float aspect, mat4 proj)
| resize perspective matrix by aspect ratio ( width / height )
this makes very easy to resize proj matrix when window / viewport reized
Parameters:
| *[in]* **aspect** aspect ratio ( width / height )
| *[in, out]* **proj** perspective projection matrix
.. c:function:: void glm_lookat(vec3 eye, vec3 center, vec3 up, mat4 dest)
| set up view matrix
.. note:: The UP vector must not be parallel to the line of sight from the eye point to the reference point.
Parameters:
| *[in]* **eye** eye vector
| *[in]* **center** center vector
| *[in]* **up** up vector
| *[out]* **dest** result matrix
.. c:function:: void glm_look(vec3 eye, vec3 dir, vec3 up, mat4 dest)
| set up view matrix
convenient wrapper for :c:func:`glm_lookat`: if you only have direction not
target self then this might be useful. Because you need to get target
from direction.
.. note:: The UP vector must not be parallel to the line of sight from the eye point to the reference point.
Parameters:
| *[in]* **eye** eye vector
| *[in]* **dir** direction vector
| *[in]* **up** up vector
| *[out]* **dest** result matrix
.. c:function:: void glm_look_anyup(vec3 eye, vec3 dir, mat4 dest)
| set up view matrix
convenient wrapper for :c:func:`glm_look` if you only have direction
and if you don't care what UP vector is then this might be useful
to create view matrix
Parameters:
| *[in]* **eye** eye vector
| *[in]* **dir** direction vector
| *[out]* **dest** result matrix
.. c:function:: void glm_persp_decomp(mat4 proj, float *nearVal, float *farVal, float *top, float *bottom, float *left, float *right)
| decomposes frustum values of perspective projection.
Parameters:
| *[in]* **eye** perspective projection matrix
| *[out]* **nearVal** near
| *[out]* **farVal** far
| *[out]* **top** top
| *[out]* **bottom** bottom
| *[out]* **left** left
| *[out]* **right** right
.. c:function:: void glm_persp_decompv(mat4 proj, float dest[6])
| decomposes frustum values of perspective projection.
| this makes easy to get all values at once
Parameters:
| *[in]* **proj** perspective projection matrix
| *[out]* **dest** array
.. c:function:: void glm_persp_decomp_x(mat4 proj, float *left, float *right)
| decomposes left and right values of perspective projection.
| x stands for x axis (left / right axis)
Parameters:
| *[in]* **proj** perspective projection matrix
| *[out]* **left** left
| *[out]* **right** right
.. c:function:: void glm_persp_decomp_y(mat4 proj, float *top, float *bottom)
| decomposes top and bottom values of perspective projection.
| y stands for y axis (top / bottom axis)
Parameters:
| *[in]* **proj** perspective projection matrix
| *[out]* **top** top
| *[out]* **bottom** bottom
.. c:function:: void glm_persp_decomp_z(mat4 proj, float *nearVal, float *farVal)
| decomposes near and far values of perspective projection.
| z stands for z axis (near / far axis)
Parameters:
| *[in]* **proj** perspective projection matrix
| *[out]* **nearVal** near
| *[out]* **farVal** far
.. c:function:: void glm_persp_decomp_far(mat4 proj, float * __restrict farVal)
| decomposes far value of perspective projection.
Parameters:
| *[in]* **proj** perspective projection matrix
| *[out]* **farVal** far
.. c:function:: void glm_persp_decomp_near(mat4 proj, float * __restrict nearVal)
| decomposes near value of perspective projection.
Parameters:
| *[in]* **proj** perspective projection matrix
| *[out]* **nearVal** near
.. c:function:: float glm_persp_fovy(mat4 proj)
| returns field of view angle along the Y-axis (in radians)
if you need to degrees, use glm_deg to convert it or use this:
fovy_deg = glm_deg(glm_persp_fovy(projMatrix))
Parameters:
| *[in]* **proj** perspective projection matrix
Returns:
| fovy in radians
.. c:function:: float glm_persp_aspect(mat4 proj)
| returns aspect ratio of perspective projection
Parameters:
| *[in]* **proj** perspective projection matrix
.. c:function:: void glm_persp_sizes(mat4 proj, float fovy, vec4 dest)
| returns sizes of near and far planes of perspective projection
Parameters:
| *[in]* **proj** perspective projection matrix
| *[in]* **fovy** fovy (see brief)
| *[out]* **dest** sizes order: [Wnear, Hnear, Wfar, Hfar]
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