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pick matrix helper (aka gluPickMatrix)

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Recep Aslantas
2021-08-16 16:53:46 +03:00
parent a2bd00df32
commit 8427d02a9b
5 changed files with 63 additions and 0 deletions
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33
include/cglm/project.h
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@@ -114,4 +114,37 @@ glm_project(vec3 pos, mat4 m, vec4 vp, vec3 dest) {
#endif
}
/*!
* @brief define a picking region
*
* @param[in] center center [x, y] of a picking region in window coordinates
* @param[in] size size [width, height] of the picking region in window coordinates
* @param[in] vp viewport as [x, y, width, height]
* @param[out] dest projected coordinates
*/
CGLM_INLINE
void
glm_pickmatrix(vec3 center, vec2 size, vec4 vp, mat4 dest) {
mat4 res;
vec3 v;
if (size[0] <= 0.0f || size[1] <= 0.0f)
return;
/* Translate and scale the picked region to the entire window */
v[0] = (vp[2] - 2.0f * (center[0] - vp[0])) / size[0];
v[1] = (vp[3] - 2.0f * (center[1] - vp[1])) / size[1];
v[2] = 0.0f;
glm_translate_make(res, v);
v[0] = vp[2] / size[0];
v[1] = vp[3] / size[1];
v[2] = 1.0f;
glm_scale(res, v);
glm_mat4_copy(res, dest);
}
#endif /* cglm_project_h */