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