Add dielectric material

include/material.h

@@ -16,6 +16,12 @@
 		.params = { .reflective = { .tint = { r, g, b } } }, \
 	}
 
+#define DIELECTRIC(e) \
+	{ \
+		.scatter = scatter_dielectric, \
+		.params = { .dielectric = { .eta = e } }, \
+	}
+
 typedef struct {
 	vec3_t point, normal;
 	double t;
@@ -30,9 +36,14 @@ typedef struct {
 	vec3_t tint;
 } reflective_params_t;
 
+typedef struct {
+	double eta;
+} dielectric_params_t;
+
 typedef union {
 	lambertian_params_t lambertian;
 	reflective_params_t reflective;
+	dielectric_params_t dielectric;
 } material_params_t;
 
 typedef bool scatter_fn_t(
@@ -50,5 +61,8 @@ bool scatter_lambertian(
 bool scatter_reflective(
     material_params_t params, hit_t hit, rng_t *rng, ray_t *ray,
     vec3_t *atten_out);
+bool scatter_dielectric(
+    material_params_t params, hit_t hit, rng_t *rng, ray_t *ray,
+    vec3_t *atten_out);
 
 #endif

include/rng.h

@@ -10,6 +10,7 @@ typedef struct {
 } rng_t;
 
 rng_t rng_init(unsigned seed);
+double rng_canon(rng_t *rng);
 vec3_t rng_vec3(rng_t *rng);
 vec3_t rng_gaussian_xy(rng_t *rng, double stddev);
 

include/vec3.h

@@ -11,6 +11,7 @@ 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_squared(vec3_t v);
 double vec3_len(vec3_t v);
 vec3_t vec3_unit(vec3_t v);