X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=csgray;a=blobdiff_plain;f=src%2Fgeom.c;fp=src%2Fgeom.c;h=ee7cb7da591213709f6a0933185c3806be8fdc68;hp=0000000000000000000000000000000000000000;hb=07ca36e28aa10804ba5a544276eb5a25f8105e0f;hpb=40a4c5772ab19e7f27c62768d40f697bf5d80a12

diff --git a/src/geom.c b/src/geom.c
new file mode 100644
index 0000000..ee7cb7d
--- /dev/null
+++ b/src/geom.c
@@ -0,0 +1,172 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include "geom.h"
+#include "matrix.h"
+
+/* TODO custom hit allocator */
+struct hit *alloc_hit(void)
+{
+	struct hit *hit = calloc(sizeof *hit, 1);
+	if(!hit) {
+		perror("failed to allocate ray hit node");
+		abort();
+	}
+	return hit;
+}
+
+void free_hit(struct hit *hit)
+{
+	free(hit);
+}
+
+void free_hit_list(struct hit *hit)
+{
+	while(hit) {
+		struct hit *tmp = hit;
+		hit = hit->next;
+		free_hit(tmp);
+	}
+}
+
+struct hit *ray_intersect(struct ray *ray, csg_object *o)
+{
+	switch(o->ob.type) {
+	case OB_SPHERE:
+		return ray_sphere(ray, o);
+	case OB_CYLINDER:
+		return ray_cylinder(ray, o);
+	case OB_PLANE:
+		return ray_plane(ray, o);
+	case OB_UNION:
+		return ray_csg_un(ray, o);
+	case OB_INTERSECTION:
+		return ray_csg_isect(ray, o);
+	case OB_SUBTRACTION:
+		return ray_csg_sub(ray, o);
+	default:
+		break;
+	}
+	return 0;
+}
+
+struct hit *ray_sphere(struct ray *ray, csg_object *o)
+{
+	float a, b, c, d, sqrt_d, t0, t1, t, sq_rad;
+	struct hit *hit;
+	struct ray locray = *ray;
+
+	if(o->sph.rad == 0.0f) {
+		return 0;
+	}
+	sq_rad = o->sph.rad * o->sph.rad;
+
+	xform_ray(&locray, o->ob.inv_xform);
+
+	a = locray.dx * locray.dx + locray.dy * locray.dy + locray.dz * locray.dz;
+	b = 2.0f * (locray.dx * locray.x + locray.dy * locray.y + locray.dz * locray.z);
+	c = (locray.x * locray.x + locray.y * locray.y + locray.z * locray.z) - sq_rad;
+
+	d = b * b - 4.0f * a * c;
+	if(d < 1e-6) return 0;
+
+	sqrt_d = sqrt(d);
+	t0 = (-b + sqrt_d) / (2.0f * a);
+	t1 = (-b - sqrt_d) / (2.0f * a);
+
+	if(t0 < 1e-6) t0 = t1;
+	if(t1 < 1e-6) t1 = t0;
+	t = t0 < t1 ? t0 : t1;
+	if(t < 1e-6) return 0;
+
+	hit = alloc_hit();
+	hit->t = t;
+	hit->x = ray->x + ray->dx * t;
+	hit->y = ray->y + ray->dy * t;
+	hit->z = ray->z + ray->dz * t;
+	hit->nx = hit->x / o->sph.rad;
+	hit->ny = hit->y / o->sph.rad;
+	hit->nz = hit->z / o->sph.rad;
+	hit->o = o;
+	return hit;
+}
+
+struct hit *ray_cylinder(struct ray *ray, csg_object *o)
+{
+	struct ray locray = *ray;
+
+	xform_ray(&locray, o->ob.inv_xform);
+	return 0;	/* TODO */
+}
+
+struct hit *ray_plane(struct ray *ray, csg_object *o)
+{
+	float vx, vy, vz, ndotv, ndotr, t;
+	struct hit *hit = 0;
+	struct ray locray = *ray;
+
+	xform_ray(&locray, o->ob.inv_xform);
+
+	vx = o->plane.nx * o->plane.d - locray.x;
+	vy = o->plane.ny * o->plane.d - locray.y;
+	vz = o->plane.nz * o->plane.d - locray.z;
+
+	ndotv = o->plane.nx * vx + o->plane.ny * vy + o->plane.nz * vz;
+	if(fabs(ndotv) < 1e-6) return 0;
+
+	ndotr = o->plane.nx * locray.dx + o->plane.ny * locray.dy + o->plane.nz * locray.dz;
+	t = ndotr / ndotv;
+
+	if(t > 1e-6) {
+		hit = alloc_hit();
+		hit->t = t;
+		hit->x = ray->x + ray->dx * t;
+		hit->y = ray->y + ray->dy * t;
+		hit->z = ray->z + ray->dz * t;
+		hit->nx = o->plane.nx;
+		hit->ny = o->plane.ny;
+		hit->nz = o->plane.nz;
+		hit->o = o;
+	}
+	return hit;
+}
+
+struct hit *ray_csg_un(struct ray *ray, csg_object *o)
+{
+	struct hit *hita, *hitb;
+
+	hita = ray_intersect(ray, o->un.a);
+	hitb = ray_intersect(ray, o->un.a);
+
+	if(!hita) return hitb;
+	if(!hitb) return hita;
+
+	if(hita->t < hitb->t) {
+		free_hit(hitb);
+		return hita;
+	}
+	free_hit(hita);
+	return hitb;
+}
+
+struct hit *ray_csg_isect(struct ray *ray, csg_object *o)
+{
+	return 0;
+}
+
+struct hit *ray_csg_sub(struct ray *ray, csg_object *o)
+{
+	return 0;
+}
+
+
+void xform_ray(struct ray *ray, float *mat)
+{
+	float m3x3[16];
+
+	mat4_copy(m3x3, mat);
+	mat4_upper3x3(m3x3);
+
+	mat4_xform3(&ray->x, mat, &ray->x);
+	mat4_xform3(&ray->dx, m3x3, &ray->dx);
+}