119 lines
3.2 KiB
C
119 lines
3.2 KiB
C
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/*
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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_project_h
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#define cglm_project_h
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#include "common.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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/*!
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* @brief maps the specified viewport coordinates into specified space [1]
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* the matrix should contain projection matrix.
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*
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* if you don't have ( and don't want to have ) an inverse matrix then use
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* glm_unproject version. You may use existing inverse of matrix in somewhere
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* else, this is why glm_unprojecti exists to save save inversion cost
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*
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* [1] space:
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* 1- if m = invProj: View Space
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* 2- if m = invViewProj: World Space
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* 3- if m = invMVP: Object Space
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*
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* You probably want to map the coordinates into object space
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* so use invMVP as m
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*
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* Computing viewProj:
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* glm_mat4_mul(proj, view, viewProj);
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* glm_mat4_mul(viewProj, model, MVP);
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* glm_mat4_inv(viewProj, invMVP);
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*
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* @param[in] pos point/position in viewport coordinates
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* @param[in] invMat matrix (see brief)
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* @param[in] vp viewport as [x, y, width, height]
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* @param[out] dest unprojected coordinates
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*/
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CGLM_INLINE
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void
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glm_unprojecti(vec3 pos, mat4 invMat, vec4 vp, vec3 dest) {
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vec4 v;
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v[0] = 2.0f * (pos[0] - vp[0]) / vp[2] - 1.0f;
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v[1] = 2.0f * (pos[1] - vp[1]) / vp[3] - 1.0f;
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v[2] = 2.0f * pos[2] - 1.0f;
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v[3] = 1.0f;
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glm_mat4_mulv(invMat, v, v);
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glm_vec4_scale(v, 1.0f / v[3], v);
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glm_vec3(v, dest);
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}
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/*!
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* @brief maps the specified viewport coordinates into specified space [1]
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* the matrix should contain projection matrix.
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*
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* this is same as glm_unprojecti except this function get inverse matrix for
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* you.
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*
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* [1] 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 map the coordinates into object space
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* so use MVP as m
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*
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* Computing viewProj and MVP:
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* glm_mat4_mul(proj, view, viewProj);
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* glm_mat4_mul(viewProj, model, MVP);
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*
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* @param[in] pos point/position in viewport coordinates
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* @param[in] m matrix (see brief)
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* @param[in] vp viewport as [x, y, width, height]
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* @param[out] dest unprojected coordinates
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*/
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CGLM_INLINE
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void
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glm_unproject(vec3 pos, mat4 m, vec4 vp, vec3 dest) {
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mat4 inv;
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glm_mat4_inv(m, inv);
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glm_unprojecti(pos, inv, vp, dest);
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}
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/*!
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* @brief map object coordinates to window coordinates
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*
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* Computing MVP:
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* glm_mat4_mul(proj, view, viewProj);
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* glm_mat4_mul(viewProj, model, MVP);
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*
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* @param[in] pos object coordinates
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* @param[in] m MVP matrix
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* @param[in] vp viewport as [x, y, width, height]
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* @param[out] dest projected coordinates
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*/
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CGLM_INLINE
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void
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glm_project(vec3 pos, mat4 m, vec4 vp, vec3 dest) {
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CGLM_ALIGN(16) vec4 pos4, vone = GLM_VEC4_ONE_INIT;
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glm_vec4(pos, 1.0f, pos4);
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glm_mat4_mulv(m, pos4, pos4);
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glm_vec4_scale(pos4, 1.0f / pos4[3], pos4); /* pos = pos / pos.w */
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glm_vec4_add(pos4, vone, pos4);
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glm_vec4_scale(pos4, 0.5f, pos4);
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dest[0] = pos4[0] * vp[2] + vp[0];
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dest[1] = pos4[1] * vp[3] + vp[1];
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dest[2] = pos4[2];
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}
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#endif /* cglm_project_h */
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