Create material abstraction

include/material.h

@@ -0,0 +1,40 @@
+#ifndef MATERIAL_H
+#define MATERIAL_H
+
+#include "ray.h"
+#include "rng.h"
+
+#define LAMBERTIAN(r, g, b) \
+	{ \
+		.scatter = scatter_lambertian, \
+		.params = { .lambertian = { .albedo = { r, g, b } } }, \
+	}
+
+typedef struct {
+	vec3_t point, normal;
+	double t;
+	bool front;
+} hit_t;
+
+typedef struct {
+	vec3_t albedo;
+} lambertian_params_t;
+
+typedef union {
+	lambertian_params_t lambertian;
+} material_params_t;
+
+typedef bool scatter_fn_t(
+    material_params_t params, hit_t hit, rng_t *rng, ray_t *ray,
+    vec3_t *atten_out);
+
+typedef struct {
+	scatter_fn_t *scatter;
+	material_params_t params;
+} material_t;
+
+bool scatter_lambertian(
+    material_params_t params, hit_t hit, rng_t *rng, ray_t *ray,
+    vec3_t *atten_out);
+
+#endif

include/obj.h

@@ -1,22 +1,18 @@
 #ifndef OBJ_H
 #define OBJ_H
 
+#include "material.h"
 #include "ray.h"
 
-#define SPHERE(x, y, z, r) \
+#define SPHERE(x, y, z, r, m) \
 	{ \
 		.intersect = intersect_sphere, \
+		.material = m, \
 		.params = { \
 			.sphere = { .centre = { x, y, z }, .radius = r }, \
 		}, \
 	}
 
-typedef struct {
-	vec3_t point, normal;
-	double t;
-	bool front;
-} hit_t;
-
 typedef struct {
 	vec3_t centre;
 	double radius;
@@ -32,6 +28,7 @@ typedef bool intersect_fn_t(
 
 typedef struct {
 	intersect_fn_t *intersect;
+	material_t material;
 	obj_params_t params;
 } obj_t;
 

include/vec3.h

@@ -10,6 +10,7 @@ vec3_t vec3_add(vec3_t v, vec3_t u);
 vec3_t vec3_sub(vec3_t v, vec3_t u);
 double vec3_dot(vec3_t v, vec3_t u);
 vec3_t vec3_cross(vec3_t v, vec3_t u);
+vec3_t vec3_hadamard(vec3_t v, vec3_t u);
 double vec3_len(vec3_t v);
 vec3_t vec3_unit(vec3_t v);