256 lines
7.1 KiB
C
256 lines
7.1 KiB
C
/*
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* Copyright (c), Recep Aslantas.
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*
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* MIT License (MIT), http://opensource.org/licenses/MIT
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* Full license can be found in the LICENSE file
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*/
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#ifndef cglm_frustum_h
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#define cglm_frustum_h
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#include "common.h"
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#include "plane.h"
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#include "vec3.h"
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#include "vec4.h"
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#include "mat4.h"
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#define GLM_LBN 0 /* left bottom near */
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#define GLM_LTN 1 /* left top near */
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#define GLM_RTN 2 /* right top near */
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#define GLM_RBN 3 /* right bottom near */
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#define GLM_LBF 4 /* left bottom far */
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#define GLM_LTF 5 /* left top far */
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#define GLM_RTF 6 /* right top far */
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#define GLM_RBF 7 /* right bottom far */
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#define GLM_LEFT 0
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#define GLM_RIGHT 1
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#define GLM_BOTTOM 2
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#define GLM_TOP 3
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#define GLM_NEAR 4
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#define GLM_FAR 5
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/* you can override clip space coords
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but you have to provide all with same name
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e.g.: define GLM_CSCOORD_LBN {0.0f, 0.0f, 1.0f, 1.0f} */
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#ifndef GLM_CUSTOM_CLIPSPACE
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/* near */
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#define GLM_CSCOORD_LBN {-1.0f, -1.0f, -1.0f, 1.0f}
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#define GLM_CSCOORD_LTN {-1.0f, 1.0f, -1.0f, 1.0f}
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#define GLM_CSCOORD_RTN { 1.0f, 1.0f, -1.0f, 1.0f}
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#define GLM_CSCOORD_RBN { 1.0f, -1.0f, -1.0f, 1.0f}
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/* far */
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#define GLM_CSCOORD_LBF {-1.0f, -1.0f, 1.0f, 1.0f}
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#define GLM_CSCOORD_LTF {-1.0f, 1.0f, 1.0f, 1.0f}
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#define GLM_CSCOORD_RTF { 1.0f, 1.0f, 1.0f, 1.0f}
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#define GLM_CSCOORD_RBF { 1.0f, -1.0f, 1.0f, 1.0f}
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#endif
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/*!
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* @brief extracts view frustum planes
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*
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* planes' space:
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* 1- if m = proj: View Space
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* 2- if m = viewProj: World Space
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* 3- if m = MVP: Object Space
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*
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* You probably want to extract planes in world space so use viewProj as m
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* Computing viewProj:
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* glm_mat4_mul(proj, view, viewProj);
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*
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* Exracted planes order: [left, right, bottom, top, near, far]
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*
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* @param[in] m matrix (see brief)
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* @param[out] dest extracted view frustum planes (see brief)
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*/
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CGLM_INLINE
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void
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glm_frustum_planes(mat4 m, vec4 dest[6]) {
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mat4 t;
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glm_mat4_transpose_to(m, t);
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glm_vec4_add(t[3], t[0], dest[0]); /* left */
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glm_vec4_sub(t[3], t[0], dest[1]); /* right */
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glm_vec4_add(t[3], t[1], dest[2]); /* bottom */
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glm_vec4_sub(t[3], t[1], dest[3]); /* top */
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glm_vec4_add(t[3], t[2], dest[4]); /* near */
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glm_vec4_sub(t[3], t[2], dest[5]); /* far */
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glm_plane_normalize(dest[0]);
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glm_plane_normalize(dest[1]);
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glm_plane_normalize(dest[2]);
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glm_plane_normalize(dest[3]);
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glm_plane_normalize(dest[4]);
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glm_plane_normalize(dest[5]);
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}
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/*!
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* @brief extracts view frustum corners using clip-space coordinates
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*
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* corners' space:
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* 1- if m = invViewProj: World Space
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* 2- if m = invMVP: Object Space
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*
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* You probably want to extract corners in world space so use invViewProj
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* Computing invViewProj:
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* glm_mat4_mul(proj, view, viewProj);
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* ...
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* glm_mat4_inv(viewProj, invViewProj);
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*
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* if you have a near coord at i index, you can get it's far coord by i + 4
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*
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* Find center coordinates:
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* for (j = 0; j < 4; j++) {
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* glm_vec3_center(corners[i], corners[i + 4], centerCorners[i]);
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* }
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*
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* @param[in] invMat matrix (see brief)
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* @param[out] dest exracted view frustum corners (see brief)
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*/
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CGLM_INLINE
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void
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glm_frustum_corners(mat4 invMat, vec4 dest[8]) {
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vec4 c[8];
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/* indexOf(nearCoord) = indexOf(farCoord) + 4 */
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vec4 csCoords[8] = {
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GLM_CSCOORD_LBN,
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GLM_CSCOORD_LTN,
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GLM_CSCOORD_RTN,
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GLM_CSCOORD_RBN,
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GLM_CSCOORD_LBF,
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GLM_CSCOORD_LTF,
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GLM_CSCOORD_RTF,
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GLM_CSCOORD_RBF
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};
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glm_mat4_mulv(invMat, csCoords[0], c[0]);
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glm_mat4_mulv(invMat, csCoords[1], c[1]);
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glm_mat4_mulv(invMat, csCoords[2], c[2]);
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glm_mat4_mulv(invMat, csCoords[3], c[3]);
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glm_mat4_mulv(invMat, csCoords[4], c[4]);
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glm_mat4_mulv(invMat, csCoords[5], c[5]);
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glm_mat4_mulv(invMat, csCoords[6], c[6]);
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glm_mat4_mulv(invMat, csCoords[7], c[7]);
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glm_vec4_scale(c[0], 1.0f / c[0][3], dest[0]);
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glm_vec4_scale(c[1], 1.0f / c[1][3], dest[1]);
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glm_vec4_scale(c[2], 1.0f / c[2][3], dest[2]);
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glm_vec4_scale(c[3], 1.0f / c[3][3], dest[3]);
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glm_vec4_scale(c[4], 1.0f / c[4][3], dest[4]);
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glm_vec4_scale(c[5], 1.0f / c[5][3], dest[5]);
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glm_vec4_scale(c[6], 1.0f / c[6][3], dest[6]);
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glm_vec4_scale(c[7], 1.0f / c[7][3], dest[7]);
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}
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/*!
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* @brief finds center of view frustum
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*
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* @param[in] corners view frustum corners
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* @param[out] dest view frustum center
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*/
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CGLM_INLINE
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void
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glm_frustum_center(vec4 corners[8], vec4 dest) {
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vec4 center;
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glm_vec4_copy(corners[0], center);
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glm_vec4_add(corners[1], center, center);
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glm_vec4_add(corners[2], center, center);
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glm_vec4_add(corners[3], center, center);
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glm_vec4_add(corners[4], center, center);
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glm_vec4_add(corners[5], center, center);
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glm_vec4_add(corners[6], center, center);
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glm_vec4_add(corners[7], center, center);
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glm_vec4_scale(center, 0.125f, dest);
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}
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/*!
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* @brief finds bounding box of frustum relative to given matrix e.g. view mat
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*
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* @param[in] corners view frustum corners
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* @param[in] m matrix to convert existing conners
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* @param[out] box bounding box as array [min, max]
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*/
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CGLM_INLINE
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void
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glm_frustum_box(vec4 corners[8], mat4 m, vec3 box[2]) {
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vec4 v;
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vec3 min, max;
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int i;
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glm_vec3_broadcast(FLT_MAX, min);
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glm_vec3_broadcast(-FLT_MAX, max);
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for (i = 0; i < 8; i++) {
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glm_mat4_mulv(m, corners[i], v);
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min[0] = glm_min(min[0], v[0]);
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min[1] = glm_min(min[1], v[1]);
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min[2] = glm_min(min[2], v[2]);
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max[0] = glm_max(max[0], v[0]);
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max[1] = glm_max(max[1], v[1]);
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max[2] = glm_max(max[2], v[2]);
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}
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glm_vec3_copy(min, box[0]);
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glm_vec3_copy(max, box[1]);
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}
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/*!
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* @brief finds planes corners which is between near and far planes (parallel)
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*
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* this will be helpful if you want to split a frustum e.g. CSM/PSSM. This will
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* find planes' corners but you will need to one more plane.
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* Actually you have it, it is near, far or created previously with this func ;)
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*
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* @param[in] corners view frustum corners
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* @param[in] splitDist split distance
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* @param[in] farDist far distance (zFar)
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* @param[out] planeCorners plane corners [LB, LT, RT, RB]
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*/
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CGLM_INLINE
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void
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glm_frustum_corners_at(vec4 corners[8],
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float splitDist,
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float farDist,
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vec4 planeCorners[4]) {
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vec4 corner;
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float dist, sc;
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/* because distance and scale is same for all */
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dist = glm_vec3_distance(corners[GLM_RTF], corners[GLM_RTN]);
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sc = dist * (splitDist / farDist);
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/* left bottom */
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glm_vec4_sub(corners[GLM_LBF], corners[GLM_LBN], corner);
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glm_vec4_scale_as(corner, sc, corner);
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glm_vec4_add(corners[GLM_LBN], corner, planeCorners[0]);
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/* left top */
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glm_vec4_sub(corners[GLM_LTF], corners[GLM_LTN], corner);
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glm_vec4_scale_as(corner, sc, corner);
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glm_vec4_add(corners[GLM_LTN], corner, planeCorners[1]);
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/* right top */
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glm_vec4_sub(corners[GLM_RTF], corners[GLM_RTN], corner);
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glm_vec4_scale_as(corner, sc, corner);
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glm_vec4_add(corners[GLM_RTN], corner, planeCorners[2]);
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/* right bottom */
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glm_vec4_sub(corners[GLM_RBF], corners[GLM_RBN], corner);
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glm_vec4_scale_as(corner, sc, corner);
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glm_vec4_add(corners[GLM_RBN], corner, planeCorners[3]);
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}
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#endif /* cglm_frustum_h */
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