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decompose projection matrix into near, far, left, right, top and bottom

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Recep Aslantas
2017-11-24 11:07:26 +03:00
parent 171668085d
commit 008de93d03
1 changed files with 101 additions and 0 deletions
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101
include/cglm/cam.h
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@@ -31,6 +31,25 @@
CGLM_INLINE void glm_perspective_default(float aspect, mat4 dest);
CGLM_INLINE void glm_perspective_resize(float aspect, mat4 proj);
CGLM_INLINE void glm_lookat(vec3 eye, vec3 center, vec3 up, mat4 dest);
CGLM_INLINE void glm_persp_decomp(mat4 proj,
float * __restrict near,
float * __restrict far,
float * __restrict top,
float * __restrict bottom,
float * __restrict left,
float * __restrict right);
CGLM_INLINE void glm_persp_decompv(mat4 proj, float dest[6]);
CGLM_INLINE void glm_persp_decomp_x(mat4 proj,
float * __restrict left,
float * __restrict right);
CGLM_INLINE void glm_persp_decomp_y(mat4 proj,
float * __restrict top,
float * __restrict bottom);
CGLM_INLINE void glm_persp_decomp_z(mat4 proj,
float * __restrict near,
float * __restrict far);
CGLM_INLINE void glm_persp_decomp_far(mat4 proj, float * __restrict far);
CGLM_INLINE void glm_persp_decomp_near(mat4 proj, float * __restrict near);
*/
#ifndef cglm_vcam_h
@@ -281,6 +300,88 @@ glm_lookat(vec3 eye,
dest[3][3] = 1.0f;
}
/*!
* @brief decomposes frustum values of perspective projection.
*
* @param[in] proj perspective projection matrix
* @param[out] near near
* @param[out] far far
* @param[out] top top
* @param[out] bottom bottom
* @param[out] left left
* @param[out] right right
*/
CGLM_INLINE
void
glm_persp_decomp(mat4 proj,
float * __restrict near,
float * __restrict far,
float * __restrict top,
float * __restrict bottom,
float * __restrict left,
float * __restrict right) {
*near = proj[3][2] / (proj[2][2] - 1);
*far = proj[3][2] / (proj[2][2] + 1);
*bottom = *near * (proj[2][1] - 1) / proj[1][1];
*top = *near * (proj[2][1] + 1) / proj[1][1];
*left = *near * (proj[2][0] - 1) / proj[0][0];
*right = *near * (proj[2][0] + 1) / proj[0][0];
}
/*!
* @brief decomposes frustum values of perspective projection.
* this makes easy to get all values at once
*
* @param[in] proj perspective projection matrix
* @param[out] dest array
*/
CGLM_INLINE
void
glm_persp_decompv(mat4 proj, float dest[6]) {
glm_persp_decomp(proj, &dest[0], &dest[1], &dest[2],
&dest[3], &dest[4], &dest[5]);
}
/*!
* @brief decomposes left and right values of perspective projection.
* x stands for x axis (left / right axis)
*
* @param[in] proj perspective projection matrix
* @param[out] left left
* @param[out] right right
*/
CGLM_INLINE
void
glm_persp_decomp_x(mat4 proj,
float * __restrict left,
float * __restrict right) {
float near;
near = proj[3][2] / (proj[3][3] - 1);
*left = near * (proj[2][0] - 1) / proj[0][0];
*right = near * (proj[2][0] + 1) / proj[0][0];
}
/*!
* @brief decomposes top and bottom values of perspective projection.
* y stands for y axis (top / botom axis)
*
* @param[in] proj perspective projection matrix
* @param[out] top top
* @param[out] bottom bottom
*/
CGLM_INLINE
void
glm_persp_decomp_y(mat4 proj,
float * __restrict top,
float * __restrict bottom) {
float near;
near = proj[3][2] / (proj[3][3] - 1);
*bottom = near * (proj[2][1] - 1) / proj[1][1];
*top = near * (proj[2][1] + 1) / proj[1][1];
}
/*!
* @brief decomposes near and far values of perspective projection.
* z stands for z axis (near / far axis)