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Diffstat (limited to 'include/cglm/ray.h')
| -rw-r--r-- | include/cglm/ray.h | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/include/cglm/ray.h b/include/cglm/ray.h new file mode 100644 index 0000000..d7831bc --- /dev/null +++ b/include/cglm/ray.h @@ -0,0 +1,174 @@ +/* + * Copyright (c), Recep Aslantas. + * + * MIT License (MIT), http://opensource.org/licenses/MIT + * Full license can be found in the LICENSE file + */ + +/* + Functions: + CGLM_INLINE bool glm_ray_triangle(vec3 origin, + vec3 direction, + vec3 v0, + vec3 v1, + vec3 v2, + float *d); + CGLM_INLINE bool glm_ray_sphere(vec3 origin, + vec3 dir, + vec4 s, + float * __restrict t1, + float * __restrict t2) + CGLM_INLINE void glm_ray_at(vec3 orig, vec3 dir, float t, vec3 point); +*/ + +#ifndef cglm_ray_h +#define cglm_ray_h + +#include "vec3.h" + +/*! + * @brief Möller–Trumbore ray-triangle intersection algorithm + * + * @param[in] origin origin of ray + * @param[in] direction direction of ray + * @param[in] v0 first vertex of triangle + * @param[in] v1 second vertex of triangle + * @param[in] v2 third vertex of triangle + * @param[in, out] d distance to intersection + * @return whether there is intersection + */ +CGLM_INLINE +bool +glm_ray_triangle(vec3 origin, + vec3 direction, + vec3 v0, + vec3 v1, + vec3 v2, + float *d) { + vec3 edge1, edge2, p, t, q; + float det, inv_det, u, v, dist; + const float epsilon = 0.000001f; + + glm_vec3_sub(v1, v0, edge1); + glm_vec3_sub(v2, v0, edge2); + glm_vec3_cross(direction, edge2, p); + + det = glm_vec3_dot(edge1, p); + if (det > -epsilon && det < epsilon) + return false; + + inv_det = 1.0f / det; + + glm_vec3_sub(origin, v0, t); + + u = inv_det * glm_vec3_dot(t, p); + if (u < 0.0f || u > 1.0f) + return false; + + glm_vec3_cross(t, edge1, q); + + v = inv_det * glm_vec3_dot(direction, q); + if (v < 0.0f || u + v > 1.0f) + return false; + + dist = inv_det * glm_vec3_dot(edge2, q); + + if (d) + *d = dist; + + return dist > epsilon; +} + +/*! + * @brief ray sphere intersection + * + * returns false if there is no intersection if true: + * + * - t1 > 0, t2 > 0: ray intersects the sphere at t1 and t2 both ahead of the origin + * - t1 < 0, t2 > 0: ray starts inside the sphere, exits at t2 + * - t1 < 0, t2 < 0: no intersection ahead of the ray ( returns false ) + * - the caller can check if the intersection points (t1 and t2) fall within a + * specific range (for example, tmin < t1, t2 < tmax) to determine if the + * intersections are within a desired segment of the ray + * + * @param[in] origin ray origin + * @param[out] dir normalized ray direction + * @param[in] s sphere [center.x, center.y, center.z, radii] + * @param[in] t1 near point1 (closer to origin) + * @param[in] t2 far point2 (farther from origin) + * + * @returns whether there is intersection + */ +CGLM_INLINE +bool +glm_ray_sphere(vec3 origin, + vec3 dir, + vec4 s, + float * __restrict t1, + float * __restrict t2) { + vec3 dp; + float r2, ddp, dpp, dscr, q, tmp, _t1, _t2; + + glm_vec3_sub(s, origin, dp); + + ddp = glm_vec3_dot(dir, dp); + dpp = glm_vec3_norm2(dp); + + /* compute the remedy term for numerical stability */ + glm_vec3_mulsubs(dir, ddp, dp); /* dp: remedy term */ + + r2 = s[3] * s[3]; + dscr = r2 - glm_vec3_norm2(dp); + + if (dscr < 0.0f) { + /* no intersection */ + return false; + } + + dscr = sqrtf(dscr); + q = (ddp >= 0.0f) ? (ddp + dscr) : (ddp - dscr); + + /* + include Press, William H., Saul A. Teukolsky, + William T. Vetterling, and Brian P. Flannery, + "Numerical Recipes in C," Cambridge University Press, 1992. + */ + _t1 = q; + _t2 = (dpp - r2) / q; + + /* adjust t1 and t2 to ensure t1 is the closer intersection */ + if (_t1 > _t2) { + tmp = _t1; + _t1 = _t2; + _t2 = tmp; + } + + *t1 = _t1; + *t2 = _t2; + + /* check if the closest intersection (t1) is behind the ray's origin */ + if (_t1 < 0.0f && _t2 < 0.0f) { + /* both intersections are behind the ray, no visible intersection */ + return false; + } + + return true; +} + +/*! + * @brief point using t by 𝐏(𝑡)=𝐀+𝑡𝐛 + * + * @param[in] orig origin of ray + * @param[in] dir direction of ray + * @param[in] t parameter + * @param[out] point point at t + */ +CGLM_INLINE +void +glm_ray_at(vec3 orig, vec3 dir, float t, vec3 point) { + vec3 dst; + glm_vec3_scale(dir, t, dst); + glm_vec3_add(orig, dst, point); +} + +#endif |