/*
* Adds the effect of the given light over the given intersection.
*
* light: Light that is being applied.
* inter: Intersection over which the light is being applied.
* normal_vec: Normal vector of the intersection point. It is passed by as a
* parameter for optimization purposes.
* rev_dir_vec: Reverse vector of the direction of the ray that comes from the
* eye. It is passed by as a parameter for optimization purposes.
* all_lights_color: Accumulated amount of light sources effect. The effect of
* the given light is added to this total.
* all_lights_color: Accumulated amount of the specular light effect. The
* specular effect of the given light is added to this total.
* conf: Configuration of the scene.
*/
void apply_light_source(Light light,
Intersection inter,
Vector normal_vec,
Vector rev_dir_vec,
Color *all_lights_color,
long double *all_spec_light,
SceneConfig conf)
{
Vector light_vec;
long double light_distance, illum_cos, att_factor, spec_cos;
Color light_filter;
Intersection* shadow_inter;
int shadow_i, shadow_inter_length;
Object shadow_obj;
// Find the vector that points from the intersection point to the light
// source, and normalize it
light_vec = subtract_vectors(light.anchor, inter.posn);
light_distance = normalize_vector(&light_vec);
// We check for any object making a shadow from that light
light_filter = (Color){ .red = 1.0, .green = 1.0, .blue = 1.0 };;
shadow_inter = get_intersections(inter.posn, light_vec, &shadow_inter_length, conf);
// If the intersection is beyond the light source, we ignore it
if(shadow_inter)
{ // Object(s) is/are actually behind the light
for(shadow_i = 0; shadow_i < shadow_inter_length && !is_color_empty(light_filter); shadow_i++)
{
if(shadow_inter[shadow_i].distance < light_distance)
{
shadow_obj = shadow_inter[shadow_i].obj;
if(shadow_obj.translucency_material)
{
light_filter = multiply_color(shadow_obj.translucency_material, multiply_colors(light_filter, shadow_obj.color));
}
else
{
light_filter = get_empty_color();
}
}
}
if(!is_color_empty(light_filter))
{
free(shadow_inter);
shadow_inter = NULL;
}
}
// If there aren't any shadows
if(!shadow_inter)
{
illum_cos = do_dot_product(normal_vec, light_vec);
// We only take it into account if the angle is lower than 90 degrees
if(illum_cos > 0)
{
Vector light_mirror_vec = subtract_vectors(multiply_vector(2 * illum_cos, normal_vec), light_vec);
// Attenuation factor, reduces the light energy depending on the distance
att_factor = get_attenuation_factor(light, light_distance);
spec_cos = do_dot_product(rev_dir_vec, light_mirror_vec);
// We add the light source effect
light_filter = multiply_color(illum_cos * inter.obj.light_material * att_factor, light_filter);
*all_lights_color = add_colors(*all_lights_color, multiply_colors(light_filter, light.color));
// The specular light, is the white stain on the objects
if(spec_cos > 0)
{
*all_spec_light += pow(spec_cos * inter.obj.specular_material * att_factor, inter.obj.specular_pow);
}
}
}
else free(shadow_inter);
}
/*
* Gets the color of the intersection by calculating light intensity,
* (which includes specular light, shadows, transparency, etc)
*
* light: Light for which the attenuation factor is calculated.
* distance: Distance between the light and an illuminated spot.
* mirror_level: Current level of reflection.
* conf: Configuration of the scene.
*/
Color get_intersection_color(Vector eye,
Vector dir_vec,
Intersection *inter_list,
int inter_length,
int mirror_level,
int transparency_level,
SceneConfig conf)
{
Intersection inter;
int light_index;
long double spec_light_factor, mirror_factor, transparency_factor;
Vector normal_vec, rev_dir_vec, reflection_vec;
Light light;
Color all_lights_color, color_found, reflection_color,
transparency_color, final_color;
inter = inter_list[transparency_level];
// Light intensity
all_lights_color = (Color){ .red = 0.0, .green = 0.0, .blue = 0.0 };
// Specular light intensity
spec_light_factor = 0.0;
normal_vec = get_normal_vector(&inter);
// Pick up the normal vector that is pointing to the eye
if(do_dot_product(normal_vec, dir_vec) > 0)
normal_vec = multiply_vector(-1, normal_vec);
// Initialize reverse direction vector for mirrors and specular light
rev_dir_vec = multiply_vector(-1, dir_vec);
for(light_index = 0; light_index < conf.lights_length; light_index++)
{
light = conf.lights[light_index];
apply_light_source(light, inter, normal_vec, rev_dir_vec, &all_lights_color, &spec_light_factor, conf);
}
// We add the environmental light of the scene
all_lights_color = add_colors(all_lights_color, multiply_color(inter.obj.light_ambiental, conf.environment_light));
if(spec_light_factor > 1.0)
spec_light_factor = 1.0;
color_found = multiply_colors(all_lights_color, inter.obj.color);
// Specular light gives a color between enlightened color and the light color.
color_found.red += (1 - color_found.red) * spec_light_factor;
color_found.green += (1 - color_found.green) * spec_light_factor;
color_found.blue += (1 - color_found.blue) * spec_light_factor;
// Get transparency color
transparency_factor = inter.obj.transparency_material;
if (transparency_level < conf.max_transparency_level &&
transparency_factor > 0.0)
{
if(transparency_level + 1 < inter_length)
{
transparency_color = get_intersection_color(eye,dir_vec,inter_list,inter_length,0,transparency_level+1, conf);
}
else
{
transparency_color = conf.background;
}
}
else
{
transparency_factor = 0.0;
transparency_color = get_empty_color();
}
// Get reflection color
mirror_factor = inter.obj.mirror_material;
if (mirror_level < conf.max_mirror_level &&
mirror_factor > 0.0)
{
reflection_vec = subtract_vectors(multiply_vector(2 * do_dot_product(normal_vec, rev_dir_vec), normal_vec), rev_dir_vec);
reflection_color = get_color(inter.posn, reflection_vec, mirror_level + 1, conf);
}
else
{
mirror_factor = 0;
reflection_color = get_empty_color();
}
// Calculate final color
transparency_color = multiply_color(transparency_factor, transparency_color);
reflection_color = multiply_color((1.0-transparency_factor) * mirror_factor, reflection_color);
color_found = multiply_color((1.0-transparency_factor) * (1.0-mirror_factor), color_found);
final_color = add_colors(transparency_color, add_colors(reflection_color, color_found));
return final_color;
}
/*
* Returns the color that is seen from the position 'eye' when looking at the
* tridimensional scene towards the direction 'dir_vec'.
*
* eye: Position from which the scene is seen.
* dir_vec: Direction at which the eye is looking. This vector must be normalized.
* mirror_level: Current level of reflection.
* conf: Configuration of the scene.
*/
Color get_color(Vector eye, Vector dir_vec, int mirror_level, SceneConfig conf)
{
Intersection *inter_list;
Color color;
// Get intersections on the given direction. Intersections are ordered from the nearest to the farthest.
int inter_list_length;
inter_list = get_intersections(eye, dir_vec, &inter_list_length, conf);
// If we don't find an intersection we return the background, otherwise we check for the intersections's color.
if (!inter_list) return conf.background;
color = get_intersection_color(eye, dir_vec, inter_list, inter_list_length, mirror_level, 0, conf);
free(inter_list);
return color;
}
void render(SDL_Surface* surface, SDL_Color color, vector offset) {
this->_render(surface, multiply_color(color,params.color_multiplier), offset);
}
