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frustum: new util for getting a plane's corners between near and far planes

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* optimize frustum box func
This commit is contained in:
Recep Aslantas
2018-01-13 21:40:34 +03:00
parent a56da8cc4a
commit 944d285e14
1 changed files with 57 additions and 8 deletions
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65
include/cglm/frustum.h
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@@ -162,22 +162,71 @@ CGLM_INLINE
void
glm_frustum_box(vec4 corners[8], mat4 m, vec3 box[2]) {
vec4 v;
vec3 min, max;
int i;
glm_vec_broadcast(0.0f, box[0]);
glm_vec_broadcast(0.0f, box[1]);
glm_vec_broadcast(0.0f, min);
glm_vec_broadcast(0.0f, max);
for (i = 0; i < 8; i++) {
glm_mat4_mulv(m, corners[i], v);
box[0][0] = glm_min(box[0][0], v[0]);
box[0][1] = glm_min(box[0][1], v[1]);
box[0][2] = glm_min(box[0][2], v[2]);
min[0] = glm_min(min[0], v[0]);
min[1] = glm_min(min[1], v[1]);
min[2] = glm_min(min[2], v[2]);
box[1][0] = glm_max(box[1][0], v[0]);
box[1][1] = glm_max(box[1][1], v[1]);
box[1][2] = glm_max(box[1][2], v[2]);
max[0] = glm_max(max[0], v[0]);
max[1] = glm_max(max[1], v[1]);
max[2] = glm_max(max[2], v[2]);
}
glm_vec_copy(min, box[0]);
glm_vec_copy(max, box[1]);
}
/*!
* @brief finds planes corners which is between near and far planes (parallel)
*
* this will be helpful if you want to split a frustum e.g. CSM/PSSM. This will
* find planes' corners but you will need to one more plane.
* Actually you have it, it is near, far or created previously with this func ;)
*
* @param[in] corners view frustum corners
* @param[in] splitDist split distance
* @param[in] farDist far distance (zFar)
* @param[out] planeCorners plane corners [LB, LT, RT, RB]
*/
CGLM_INLINE
void
glm_frustum_corners_at(vec4 corners[8],
float splitDist,
float farDist,
vec4 planeCorners[4]) {
vec4 corner;
float dist, sc;
dist = glm_vec_distance(corners[4], corners[0]);
sc = dist * (splitDist / farDist);
/* left bottom */
glm_vec4_sub(corners[4], corners[0], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[0], corner, planeCorners[0]);
/* left top */
glm_vec4_sub(corners[5], corners[1], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[1], corner, planeCorners[1]);
/* right top */
glm_vec4_sub(corners[6], corners[2], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[2], corner, planeCorners[2]);
/* right bottom */
glm_vec4_sub(corners[7], corners[3], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[3], corner, planeCorners[3]);
}
#endif /* cglm_frustum_h */