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/*
* Copyright (c), Recep Aslantas.
*
* MIT License (MIT), http://opensource.org/licenses/MIT
* Full license can be found in the LICENSE file
*/
#ifndef cglm_frustum_h
#define cglm_frustum_h
#include "common.h"
#include "plane.h"
#include "vec3.h"
#include "vec4.h"
#include "mat4.h"
#define GLM_LBN 0 /* left bottom near */
#define GLM_LTN 1 /* left top near */
#define GLM_RTN 2 /* right top near */
#define GLM_RBN 3 /* right bottom near */
#define GLM_LBF 4 /* left bottom far */
#define GLM_LTF 5 /* left top far */
#define GLM_RTF 6 /* right top far */
#define GLM_RBF 7 /* right bottom far */
#define GLM_LEFT 0
#define GLM_RIGHT 1
#define GLM_BOTTOM 2
#define GLM_TOP 3
#define GLM_NEAR 4
#define GLM_FAR 5
/* you can override clip space coords
but you have to provide all with same name
e.g.: define GLM_CSCOORD_LBN {0.0f, 0.0f, 1.0f, 1.0f} */
#ifndef GLM_CUSTOM_CLIPSPACE
/* near */
#define GLM_CSCOORD_LBN {-1.0f, -1.0f, -1.0f, 1.0f}
#define GLM_CSCOORD_LTN {-1.0f, 1.0f, -1.0f, 1.0f}
#define GLM_CSCOORD_RTN { 1.0f, 1.0f, -1.0f, 1.0f}
#define GLM_CSCOORD_RBN { 1.0f, -1.0f, -1.0f, 1.0f}
/* far */
#define GLM_CSCOORD_LBF {-1.0f, -1.0f, 1.0f, 1.0f}
#define GLM_CSCOORD_LTF {-1.0f, 1.0f, 1.0f, 1.0f}
#define GLM_CSCOORD_RTF { 1.0f, 1.0f, 1.0f, 1.0f}
#define GLM_CSCOORD_RBF { 1.0f, -1.0f, 1.0f, 1.0f}
#endif
/*!
* @brief extracts view frustum planes
*
* planes' space:
* 1- if m = proj: View Space
* 2- if m = viewProj: World Space
* 3- if m = MVP: Object Space
*
* You probably want to extract planes in world space so use viewProj as m
* Computing viewProj:
* glm_mat4_mul(proj, view, viewProj);
*
* Exracted planes order: [left, right, bottom, top, near, far]
*
* @param[in] m matrix (see brief)
* @param[out] dest extracted view frustum planes (see brief)
*/
CGLM_INLINE
void
glm_frustum_planes(mat4 m, vec4 dest[6]) {
mat4 t;
glm_mat4_transpose_to(m, t);
glm_vec4_add(t[3], t[0], dest[0]); /* left */
glm_vec4_sub(t[3], t[0], dest[1]); /* right */
glm_vec4_add(t[3], t[1], dest[2]); /* bottom */
glm_vec4_sub(t[3], t[1], dest[3]); /* top */
glm_vec4_add(t[3], t[2], dest[4]); /* near */
glm_vec4_sub(t[3], t[2], dest[5]); /* far */
glm_plane_normalize(dest[0]);
glm_plane_normalize(dest[1]);
glm_plane_normalize(dest[2]);
glm_plane_normalize(dest[3]);
glm_plane_normalize(dest[4]);
glm_plane_normalize(dest[5]);
}
/*!
* @brief extracts view frustum corners using clip-space coordinates
*
* corners' space:
* 1- if m = invViewProj: World Space
* 2- if m = invMVP: Object Space
*
* You probably want to extract corners in world space so use invViewProj
* Computing invViewProj:
* glm_mat4_mul(proj, view, viewProj);
* ...
* glm_mat4_inv(viewProj, invViewProj);
*
* if you have a near coord at i index, you can get it's far coord by i + 4
*
* Find center coordinates:
* for (j = 0; j < 4; j++) {
* glm_vec3_center(corners[i], corners[i + 4], centerCorners[i]);
* }
*
* @param[in] invMat matrix (see brief)
* @param[out] dest exracted view frustum corners (see brief)
*/
CGLM_INLINE
void
glm_frustum_corners(mat4 invMat, vec4 dest[8]) {
vec4 c[8];
/* indexOf(nearCoord) = indexOf(farCoord) + 4 */
vec4 csCoords[8] = {
GLM_CSCOORD_LBN,
GLM_CSCOORD_LTN,
GLM_CSCOORD_RTN,
GLM_CSCOORD_RBN,
GLM_CSCOORD_LBF,
GLM_CSCOORD_LTF,
GLM_CSCOORD_RTF,
GLM_CSCOORD_RBF
};
glm_mat4_mulv(invMat, csCoords[0], c[0]);
glm_mat4_mulv(invMat, csCoords[1], c[1]);
glm_mat4_mulv(invMat, csCoords[2], c[2]);
glm_mat4_mulv(invMat, csCoords[3], c[3]);
glm_mat4_mulv(invMat, csCoords[4], c[4]);
glm_mat4_mulv(invMat, csCoords[5], c[5]);
glm_mat4_mulv(invMat, csCoords[6], c[6]);
glm_mat4_mulv(invMat, csCoords[7], c[7]);
glm_vec4_scale(c[0], 1.0f / c[0][3], dest[0]);
glm_vec4_scale(c[1], 1.0f / c[1][3], dest[1]);
glm_vec4_scale(c[2], 1.0f / c[2][3], dest[2]);
glm_vec4_scale(c[3], 1.0f / c[3][3], dest[3]);
glm_vec4_scale(c[4], 1.0f / c[4][3], dest[4]);
glm_vec4_scale(c[5], 1.0f / c[5][3], dest[5]);
glm_vec4_scale(c[6], 1.0f / c[6][3], dest[6]);
glm_vec4_scale(c[7], 1.0f / c[7][3], dest[7]);
}
/*!
* @brief finds center of view frustum
*
* @param[in] corners view frustum corners
* @param[out] dest view frustum center
*/
CGLM_INLINE
void
glm_frustum_center(vec4 corners[8], vec4 dest) {
vec4 center;
glm_vec4_copy(corners[0], center);
glm_vec4_add(corners[1], center, center);
glm_vec4_add(corners[2], center, center);
glm_vec4_add(corners[3], center, center);
glm_vec4_add(corners[4], center, center);
glm_vec4_add(corners[5], center, center);
glm_vec4_add(corners[6], center, center);
glm_vec4_add(corners[7], center, center);
glm_vec4_scale(center, 0.125f, dest);
}
/*!
* @brief finds bounding box of frustum relative to given matrix e.g. view mat
*
* @param[in] corners view frustum corners
* @param[in] m matrix to convert existing conners
* @param[out] box bounding box as array [min, max]
*/
CGLM_INLINE
void
glm_frustum_box(vec4 corners[8], mat4 m, vec3 box[2]) {
vec4 v;
vec3 min, max;
int i;
glm_vec3_broadcast(FLT_MAX, min);
glm_vec3_broadcast(-FLT_MAX, max);
for (i = 0; i < 8; i++) {
glm_mat4_mulv(m, corners[i], v);
min[0] = glm_min(min[0], v[0]);
min[1] = glm_min(min[1], v[1]);
min[2] = glm_min(min[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_vec3_copy(min, box[0]);
glm_vec3_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;
/* because distance and scale is same for all */
dist = glm_vec3_distance(corners[GLM_RTF], corners[GLM_RTN]);
sc = dist * (splitDist / farDist);
/* left bottom */
glm_vec4_sub(corners[GLM_LBF], corners[GLM_LBN], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[GLM_LBN], corner, planeCorners[0]);
/* left top */
glm_vec4_sub(corners[GLM_LTF], corners[GLM_LTN], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[GLM_LTN], corner, planeCorners[1]);
/* right top */
glm_vec4_sub(corners[GLM_RTF], corners[GLM_RTN], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[GLM_RTN], corner, planeCorners[2]);
/* right bottom */
glm_vec4_sub(corners[GLM_RBF], corners[GLM_RBN], corner);
glm_vec4_scale_as(corner, sc, corner);
glm_vec4_add(corners[GLM_RBN], corner, planeCorners[3]);
}
#endif /* cglm_frustum_h */
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