From 623fee395425ab33f14fb9cd8ffa790e362f59d7 Mon Sep 17 00:00:00 2001 From: Julian T Date: Fri, 21 Feb 2020 06:55:27 +0100 Subject: Added pgm drawing and got light ray tracing working Still needs correct light simulation and reflections --- ray.c | 141 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 132 insertions(+), 9 deletions(-) (limited to 'ray.c') diff --git a/ray.c b/ray.c index d2b15cc..3736773 100644 --- a/ray.c +++ b/ray.c @@ -1,3 +1,4 @@ +#include #include #include "vector.h" @@ -5,7 +6,8 @@ // https://en.wikipedia.org/wiki/Line%E2%80%93sphere_intersection // http://viclw17.github.io/2018/07/16/raytracing-ray-sphere-intersection/ -COORD_T ray_intersect_sphere(sphere_t *s, ray_t *ray) +// https://www.scratchapixel.com/lessons/3d-basic-rendering/minimal-ray-tracer-rendering-simple-shapes/ray-sphere-intersection +COORD_T ray_intersect_sphere(sphere_t *s, ray_t *ray, bool skip_dist) { // Vector between vector start and center of circle vector_t oc; @@ -13,8 +15,8 @@ COORD_T ray_intersect_sphere(sphere_t *s, ray_t *ray) // Solve quadratic function // TODO Not sure if this step i neccesary because dir is unit - COORD_T a = vector_dot(&ray->direction, &ray->direction); - COORD_T b = 2 * vector_dot(&oc, &ray->direction); + COORD_T a = vector_dot(ray->direction, ray->direction); + COORD_T b = 2 * vector_dot(&oc, ray->direction); COORD_T c = vector_dot(&oc, &oc) - s->radius * s->radius; COORD_T d = b * b - 4 * a * c; @@ -23,29 +25,150 @@ COORD_T ray_intersect_sphere(sphere_t *s, ray_t *ray) if (d < 0) { return -1; } + if (skip_dist) { + return 1; + } + + // Else take the closest intersection, reuse d + COORD_T q = (b > 0) ? + -0.5 * (b + sqrt(d)) : + -0.5 * (b - sqrt(d)); + + COORD_T x0 = q / a; + COORD_T x1 = c / q; + + // Take the correct result. If one is zero take the other. + if (x0 <= 0) { + if (x1 <= 0) { + return -1; + } + + x0 = x1; + } + + // If point is on sphere it will be zero close to zero + if (x0 < 1e-3) { + return -1; + } - // Else take the closest intersection - return (-b - sqrt(d) ) / (2.0 * a); + return x0; } // Requires that vectors are normalized // https://www.scratchapixel.com/lessons/3d-basic-rendering/minimal-ray-tracer-rendering-simple-shapes/ray-plane-and-ray-disk-intersection -COORD_T ray_intersect_plane(plane_t *p, ray_t *ray) +COORD_T ray_intersect_plane(plane_t *p, ray_t *ray, bool skip_dist) { // If zero ray is parralel to plane - COORD_T nr = vector_dot(&p->norm, &ray->direction); - vector_print(&ray->direction); + COORD_T nr = vector_dot(p->norm, ray->direction); // // Take care of rounding errors if (nr < ZERO_APROX && nr > -ZERO_APROX) { return -1; } + if (skip_dist) { + return 1; + } // Calculate distance vector_t tmp; vector_copy(&tmp, p->start); vector_sub(&tmp, &tmp, ray->start); - COORD_T t = vector_dot(&tmp, &p->norm) / nr; + COORD_T t = vector_dot(&tmp, p->norm) / nr; return t; } + +COORD_T ray_intersect(object_t *o, ray_t *ray, bool skip_dist) +{ + switch (o->type) { + case TYPE_PLANE: + return ray_intersect_plane(&o->pl, ray, skip_dist); + case TYPE_SPHERE: + return ray_intersect_sphere(&o->sph, ray, skip_dist); + default: + printf("Unknown object type %d\n", o->type); + return -1; + } +} + +// If chk is true, will return at first hit less than chk_dist +object_t *ray_cast(space_t *s, ray_t *r, COORD_T *dist_ret, bool chk, COORD_T chk_dist) +{ + object_t *o = s->objects; + + object_t *smallest = NULL; + COORD_T dist = 0; + + while (o) { + COORD_T d = ray_intersect(o, r, false); + + if (d > 0) { + if (chk && chk_dist > d) { + if (dist_ret) { + *dist_ret = d; + } + return o; + } + if (d < dist || smallest == NULL) { + dist = d; + smallest = o; + } + } + + o = o->next; + } + + if (chk) { + return NULL; + } + + if (dist_ret) { + *dist_ret = dist; + } + return smallest; +} + +color_t *ray_trace(space_t *s, unsigned int x, unsigned int y) +{ + // Setup primary ray + ray_t r; + r.start = &s->view.position; + r.direction = vector_copy(NULL, NULL); + viewpoint_ray(&s->view, r.direction, x, y); + + // Cast it + COORD_T dist; + object_t *o = ray_cast(s, &r, &dist, false, 0); + if (!o) { + return NULL; + } + //printf("dist: %f\n", dist); + + // Calculate new ray point + r.start = vector_scale(NULL, r.direction, dist); + vector_add(r.start, r.start, &s->view.position); + + // Cast light rays + light_t *l = s->lights; + while (l) { + vector_t tmp; + // Calculate distance to light + vector_sub(&tmp, l->pos, r.start); + COORD_T d = vector_len(&tmp); + + // Calculate unit + vector_scale_inv(&tmp, &tmp, vector_len(&tmp)); + + // Find obstacles + r.direction = &tmp; + object_t *obs = ray_cast(s, &r, NULL, true, d); + + if (!obs) { + return color_set(NULL, 100, 100, o->type == TYPE_SPHERE ? 200 :0); + } + + l = l->next; + } + + return NULL; +} -- cgit v1.2.3