1 files changed, 90 insertions, 0 deletions
diff --git a/src/modules/ray/ray_render_object_sphere.h b/src/modules/ray/ray_render_object_sphere.h
new file mode 100644
index 0000000..548eb6b
--- /dev/null
+++ b/src/modules/ray/ray_render_object_sphere.h
@@ -0,0 +1,90 @@
+#ifndef _RAY_RENDER_OBJECT_SPHERE_H
+#define _RAY_RENDER_OBJECT_SPHERE_H
+
+#include <math.h>
+
+#include "ray_3f.h"
+#include "ray_camera.h"
+#include "ray_color.h"
+#include "ray_object_sphere.h"
+#include "ray_object_type.h"
+#include "ray_ray.h"
+#include "ray_surface.h"
+
+
+typedef struct ray_render_object_sphere_t {
+	ray_object_sphere_t	object;
+	ray_3f_t		primary_v;
+	float			primary_dot_vv;
+	float			r2;
+	float			r_inv;
+} ray_render_object_sphere_t;
+
+
+static ray_render_object_sphere_t ray_render_object_sphere_prepare(ray_object_sphere_t *sphere, ray_camera_t *camera)
+{
+	ray_render_object_sphere_t	prepared = { .object = *sphere };
+
+	prepared.primary_v = ray_3f_sub(&sphere->center, &camera->position);
+	prepared.primary_dot_vv = ray_3f_dot(&prepared.primary_v, &prepared.primary_v);
+
+	prepared.r2 = sphere->radius * sphere->radius;
+
+	/* to divide by radius via multiplication in ray_object_sphere_normal() */
+	prepared.r_inv = 1.0f / sphere->radius;
+
+	return prepared;
+}
+
+
+static inline int ray_render_object_sphere_intersects_ray(ray_render_object_sphere_t *sphere, unsigned depth, ray_ray_t *ray, float *res_distance)
+{
+	ray_3f_t	v = sphere->primary_v;
+	float		dot_vv = sphere->primary_dot_vv;
+	float		b, disc;
+
+	if (depth) {
+		v = ray_3f_sub(&sphere->object.center, &ray->origin);
+		dot_vv = ray_3f_dot(&v, &v);
+	}
+
+	b = ray_3f_dot(&v, &ray->direction);
+	disc = sphere->r2 - (dot_vv - (b * b));
+	if (disc > 0) {
+		float	i1, i2;
+
+		disc = sqrtf(disc);
+
+		i1 = b - disc;
+		i2 = b + disc;
+
+		if (i2 > 0 && i1 > 0) {
+			*res_distance = i1;
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+
+/* return the normal of the surface at the specified point */
+static inline ray_3f_t ray_render_object_sphere_normal(ray_render_object_sphere_t *sphere, ray_3f_t *point)
+{
+	ray_3f_t	normal;
+
+	normal = ray_3f_sub(point, &sphere->object.center);
+	normal = ray_3f_mult_scalar(&normal, sphere->r_inv);	/* normalize without the sqrt() */
+
+	return normal;
+}
+
+
+/* return the surface of the sphere @ point */
+static inline ray_surface_t ray_render_object_sphere_surface(ray_render_object_sphere_t *sphere, ray_3f_t *point)
+{
+	/* uniform solids for now... */
+	return sphere->object.surface;
+}
+
+#endif