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trace.c
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trace.c
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#include <ray_trace.h>
private BOOLEAN ray_intersects_objects(
Point *origin,
Vector *direction,
int n_objects,
ray_trace_object objects[],
BOOLEAN use_flags[],
int *obj_index,
Point *point,
Vector *normal,
Colour *colour,
Surfprop *spr,
Real *closest_dist );
private void get_ray(
view_struct *view,
Real x_pixel,
Real y_pixel,
Point *origin,
Vector *direction )
{
Vector x_offset, y_offset, z_offset, offset;
Real x_position, y_position;
Point screen_position;
x_position = -view->window_width / 2.0 + view->window_width *
(x_pixel + 0.5) / (Real) view->x_viewport_size;
y_position = -view->window_height / 2.0 + view->window_height *
(y_pixel + 0.5) / (Real) view->y_viewport_size;
if( view->perspective_flag )
{
fill_Vector( screen_position,
RPoint_x(view->eye) +
x_position * RVector_x(view->horizontal) +
y_position * RVector_x(view->vertical) +
view->window_distance * RVector_x(view->line_of_sight),
RPoint_y(view->eye) +
x_position * RVector_y(view->horizontal) +
y_position * RVector_y(view->vertical) +
view->window_distance * RVector_y(view->line_of_sight),
RPoint_z(view->eye) +
x_position * RVector_z(view->horizontal) +
y_position * RVector_z(view->vertical) +
view->window_distance * RVector_z(view->line_of_sight) );
SCALE_VECTOR( offset, view->horizontal, view->stereo_offset );
ADD_POINT_VECTOR( *origin, view->eye, offset );
SUB_POINTS( *direction, screen_position, *origin );
NORMALIZE_VECTOR( *direction, *direction );
}
else
{
SCALE_VECTOR( x_offset, view->horizontal, x_position );
SCALE_VECTOR( y_offset, view->vertical, y_position );
SCALE_VECTOR( z_offset, view->line_of_sight, view->window_distance );
ADD_POINT_VECTOR( screen_position, view->eye, z_offset );
ADD_POINT_VECTOR( screen_position, screen_position, x_offset );
ADD_POINT_VECTOR( screen_position, screen_position, y_offset );
SUB_POINT_VECTOR( *origin, screen_position, z_offset );
*direction = z_offset;
NORMALIZE_VECTOR( *direction, *direction );
}
}
private void get_light_component(
int n_objects,
ray_trace_object objects[],
light_struct *light,
BOOLEAN doing_shadows,
Real shadow_offset,
Vector *view_direction,
Point *point,
Vector *normal,
Surfprop *spr,
Real r,
Real g,
Real b,
Real *r_comp,
Real *g_comp,
Real *b_comp )
{
Real n_dot_l, n_dot_h, attenuation, dist, denominator;
Vector highlight, to_light;
*r_comp = 0.0;
*g_comp = 0.0;
*b_comp = 0.0;
switch( light->type )
{
case DIRECTIONAL_LIGHT:
case POINT_LIGHT:
if( light->type == DIRECTIONAL_LIGHT )
{
SCALE_VECTOR( to_light, light->direction, -1.0 );
}
else
{
SUB_POINTS( to_light, light->position, *point );
NORMALIZE_VECTOR( to_light, to_light );
}
n_dot_l = DOT_VECTORS( *normal, to_light );
if( n_dot_l <= 0.0 )
break;
if( doing_shadows )
{
Point origin;
Vector offset;
SCALE_VECTOR( offset, to_light, shadow_offset );
ADD_POINT_VECTOR( origin, *point, offset );
if( ray_intersects_objects( &origin, &to_light, n_objects, objects,
NULL, (int *) NULL,
(Point *) NULL, (Vector *) NULL,
(Colour *) NULL, (Surfprop *) NULL,
&dist ) &&
(light->type == DIRECTIONAL_LIGHT ||
dist < distance_between_points( point, &light->position )) )
{
break;
}
}
if( n_dot_l > 0.0 )
{
*r_comp = r * n_dot_l * (Real) Surfprop_d( *spr );
*g_comp = g * n_dot_l * (Real) Surfprop_d( *spr );
*b_comp = b * n_dot_l * (Real) Surfprop_d( *spr );
}
SUB_VECTORS( highlight, *view_direction, to_light );
NORMALIZE_VECTOR( highlight, highlight );
n_dot_h = -DOT_VECTORS( *normal, highlight );
if( n_dot_h > 0.0 )
{
n_dot_h = pow( n_dot_h, (Real) Surfprop_se( *spr ) );
*r_comp += r * n_dot_h * (Real) Surfprop_s( *spr );
*g_comp += g * n_dot_h * (Real) Surfprop_s( *spr );
*b_comp += b * n_dot_h * (Real) Surfprop_s( *spr );
}
if( light->type == POINT_LIGHT &&
(light->attenuation[0] != 0.0 ||
light->attenuation[1] != 0.0 ||
light->attenuation[2] != 0.0) )
{
dist = distance_between_points( &light->position, point );
denominator = light->attenuation[0] + dist * (
light->attenuation[1] + dist * light->attenuation[2]);
if( denominator <= 1.0 )
attenuation = 1.0;
else
attenuation = 1.0 / denominator;
}
else
attenuation = 1.0;
*r_comp *= attenuation * get_Colour_r_0_1( light->colour );
*g_comp *= attenuation * get_Colour_g_0_1( light->colour );
*b_comp *= attenuation * get_Colour_b_0_1( light->colour );
break;
}
}
private BOOLEAN ray_intersects_regular_object(
Point *origin,
Vector *direction,
object_struct *object,
render_struct *render,
Point *point,
Vector *normal,
Colour *colour,
Surfprop *spr,
Real *dist )
{
model_struct *model;
BOOLEAN found, flat_shading;
int i;
Point a_point;
Vector a_normal;
Colour a_colour;
Surfprop a_spr;
Real this_dist;
static Surfprop default_line_spr = { 0.3f, 0.6f, 0.6f, 40.0f, 1.0f };
if( render == NULL )
flat_shading = TRUE;
else
flat_shading = render->flat_shading_flag;
switch( get_object_type( object ) )
{
case MODEL:
model = get_model_ptr( object );
found = FALSE;
*dist = 0.0;
for_less( i, 0, model->n_objects )
{
if( ray_intersects_regular_object( origin, direction,
model->objects[i], render,
&a_point, &a_normal, &a_colour, &a_spr, &this_dist))
{
if( !found || this_dist < *dist )
{
found = TRUE;
*dist = this_dist;
if( point != (Point *) NULL )
{
*point = a_point;
*normal = a_normal;
*colour = a_colour;
*spr = a_spr;
}
}
}
}
break;
case POLYGONS:
found = ray_intersects_a_polygon( origin, direction, object,
flat_shading, point,
normal, colour, dist );
if( found )
*spr = *get_object_surfprop(object);
break;
case QUADMESH:
found = ray_intersects_a_quadmesh( origin, direction, object,
flat_shading, point,
normal, colour, dist );
if( found )
*spr = *get_object_surfprop(object);
break;
case LINES:
found = ray_intersects_a_line( origin, direction, object,
point, normal, colour, dist );
if( found )
*spr = default_line_spr;
break;
case MARKER:
found = ray_intersects_a_marker( origin, direction, object,
point, normal, colour, dist );
if( found )
*spr = default_line_spr;
break;
default:
print_error( "ray_intersects_object(): not implemented\n" );
break;
}
return( found );
}
private void sort_reals(
int n,
Real values[] )
{
Real swap;
int i, j, best;
for_less( i, 0, n-1 )
{
best = i;
for_less( j, i+1, n )
{
if( values[j] < values[best] )
best = j;
}
swap = values[i];
values[i] = values[best];
values[best] = swap;
}
}
#define TOLERANCE 1.0e-6
#define DEFAULT_SIZE 100
typedef struct
{
Real *start_intervals;
Real start_intervals_fixed[DEFAULT_SIZE];
int start_size;
Real *end_intervals;
Real end_intervals_fixed[DEFAULT_SIZE];
int end_size;
Real *new_start_intervals;
Real new_start_intervals_fixed[DEFAULT_SIZE];
int new_start_size;
Real *new_end_intervals;
Real new_end_intervals_fixed[DEFAULT_SIZE];
int new_end_size;
} intervals_struct;
private void initialize_intervals(
intervals_struct *is )
{
is->start_intervals = is->start_intervals_fixed;
is->end_intervals = is->end_intervals_fixed;
is->new_start_intervals = is->new_start_intervals_fixed;
is->new_end_intervals = is->new_end_intervals_fixed;
is->start_size = DEFAULT_SIZE;
is->end_size = DEFAULT_SIZE;
is->new_start_size = DEFAULT_SIZE;
is->new_end_size = DEFAULT_SIZE;
}
private void delete_intervals(
intervals_struct *is )
{
if( is->start_size > DEFAULT_SIZE )
FREE( is->start_intervals );
if( is->end_size > DEFAULT_SIZE )
FREE( is->end_intervals );
if( is->new_start_size > DEFAULT_SIZE )
FREE( is->new_start_intervals );
if( is->new_end_size > DEFAULT_SIZE )
FREE( is->new_end_intervals );
}
#define ADD_ELEMENT( intervals, n_alloced, index, value ) \
{ \
if( (index) >= (n_alloced) ) \
{ \
if( (n_alloced) == DEFAULT_SIZE ) \
{ \
Real *_ptr; \
_ptr = NULL; \
SET_ARRAY_SIZE( _ptr, 0, (index)+1, DEFAULT_CHUNK_SIZE ); \
(void) memcpy( (void *) _ptr, (void *) intervals, \
(size_t) (index) * sizeof(*(intervals))); \
(intervals) = _ptr; \
} \
else \
{ \
SET_ARRAY_SIZE( intervals, n_alloced, (index) + 1, \
DEFAULT_CHUNK_SIZE ); \
} \
(n_alloced) = (index) + 1; \
} \
(intervals)[index] = (value); \
++(index); \
}
private int get_ray_clip_intervals(
Point *origin,
Vector *direction,
clip_struct *clip,
intervals_struct *is )
{
Real dist, *intersections;
Real start_invalid, end_invalid, start, end, *tmp;
int n, n_intersections, new_n, object_index, i, j, k, n_new_intervals;
int n_to_do, tmp_int;
BOOLEAN clip_inside;
is->start_intervals[0] = 0.0;
is->end_intervals[0] = 1.0e60;
n = 1;
for_less( i, 0, clip->n_clip_objects )
{
n_intersections = intersect_ray_with_object( origin, direction,
clip->clip_objects[i],
&object_index, &dist,
&intersections );
sort_reals( n_intersections, intersections );
new_n = 0;
for_less( k, 0, n_intersections )
{
if( k == 0 || !numerically_close( intersections[k],
intersections[k-1], TOLERANCE ) )
{
intersections[new_n] = intersections[k];
++new_n;
}
}
n_intersections = new_n;
#ifdef DEBUG
if( n_intersections % 2 == 1 )
{
print( "N intersections: %d : ", n_intersections );
for_less( k, 0, n_intersections )
print( " %g", intersections[k] );
print( "\n" );
}
#endif
clip_inside = clip->clip_inside_flags[i];
if( n_intersections == 0 && clip_inside || n_intersections % 2 == 1 )
{
if( n_intersections > 0 )
FREE( intersections );
continue;
}
n_to_do = n_intersections / 2;
if( !clip_inside )
++n_to_do;
start_invalid = 0.0;
for_less( j, 0, n_to_do )
{
if( clip_inside )
{
start_invalid = intersections[2*j];
end_invalid = intersections[2*j+1];
}
else
{
if( j == 0 )
start_invalid = 0.0;
else
start_invalid = intersections[2*j-1];
if( j < n_intersections/2 )
end_invalid = intersections[2*j];
else
end_invalid = 1.0e60;
}
n_new_intervals = 0;
for_less( k, 0, n )
{
start = is->start_intervals[k];
end = is->end_intervals[k];
if( end <= start_invalid || start >= end_invalid )
{
ADD_ELEMENT( is->new_start_intervals,
is->new_start_size, n_new_intervals, start );
--n_new_intervals;
ADD_ELEMENT( is->new_end_intervals,
is->new_end_size, n_new_intervals, end );
}
else if( start < start_invalid || end > end_invalid )
{
if( start < start_invalid )
{
ADD_ELEMENT( is->new_start_intervals,
is->new_start_size,
n_new_intervals, start );
--n_new_intervals;
ADD_ELEMENT( is->new_end_intervals, is->new_end_size,
n_new_intervals, start_invalid );
}
if( end > end_invalid )
{
ADD_ELEMENT( is->new_start_intervals,
is->new_start_size, n_new_intervals,
end_invalid );
--n_new_intervals;
ADD_ELEMENT( is->new_end_intervals, is->new_end_size,
n_new_intervals, end );
}
}
}
tmp = is->start_intervals;
is->start_intervals = is->new_start_intervals;
is->new_start_intervals = tmp;
tmp = is->end_intervals;
is->end_intervals = is->new_end_intervals;
is->new_end_intervals = tmp;
tmp_int = is->start_size;
is->start_size = is->new_start_size;
is->new_start_size = tmp_int;
tmp_int = is->end_size;
is->end_size = is->new_end_size;
is->new_end_size = tmp_int;
n = n_new_intervals;
}
if( n_intersections > 0 )
FREE( intersections );
if( n == 0 )
break;
}
return( n );
}
private BOOLEAN ray_intersects_object(
Point *origin,
Vector *direction,
ray_trace_object *object,
Point *point,
Vector *normal,
Colour *colour,
Surfprop *spr,
Real *dist,
intervals_struct *is )
{
int interval, n_intervals;
BOOLEAN found;
Point clip_origin;
n_intervals = get_ray_clip_intervals( origin, direction,
&object->clip, is );
found = FALSE;
for_less( interval, 0, n_intervals )
{
GET_POINT_ON_RAY( clip_origin, *origin, *direction,
is->start_intervals[interval] );
if( object->regular_object_flag )
{
found = ray_intersects_regular_object( &clip_origin, direction,
object->object, &object->render,
point, normal, colour, spr, dist );
}
else
{
found = ray_intersects_a_volume( &clip_origin, direction,
object->render.volumes[
object->render.n_volumes-1].
volume,
object->render.volumes[
object->render.n_volumes-1].
continuity,
&object->done_bits,
&object->surface_bits,
object->threshold, point, normal,
dist );
if( found )
{
*colour = object->colour;
*spr = object->spr;
}
}
if( found )
{
*dist += is->start_intervals[interval];
if( *dist <= is->end_intervals[interval] )
break;
found = FALSE;
}
}
return( found );
}
private BOOLEAN ray_intersects_objects(
Point *origin,
Vector *direction,
int n_objects,
ray_trace_object objects[],
BOOLEAN use_flags[],
int *obj_index,
Point *point,
Vector *normal,
Colour *colour,
Surfprop *spr,
Real *closest_dist )
{
int i;
Point a_point;
Vector a_normal;
Colour a_colour;
Surfprop a_spr;
Real dist;
BOOLEAN found;
intervals_struct is;
found = FALSE;
*closest_dist = 0.0;
initialize_intervals( &is );
for_less( i, 0, n_objects )
{
if( (use_flags == NULL || use_flags[i]) &&
ray_intersects_object( origin, direction, &objects[i],
&a_point, &a_normal, &a_colour, &a_spr,
&dist, &is ) )
{
if( !found || dist < *closest_dist )
{
found = TRUE;
*closest_dist = dist;
if( obj_index != NULL )
*obj_index = i;
if( point != (Point *) NULL )
{
*point = a_point;
*normal = a_normal;
*colour = a_colour;
*spr = a_spr;
}
}
}
}
delete_intervals( &is );
return( found );
}
private BOOLEAN recursive_ray_trace_one(
Point *origin,
Vector *direction,
lights_struct *lights,
int n_objects,
ray_trace_object objects[],
BOOLEAN use_flags[],
int max_depth,
Real *r,
Real *g,
Real *b,
Real *a )
{
int i, v, object_index;
Colour object_colour, col_code, cum_col;
Point intersection_point, new_origin;
Vector normal, offset;
Real voxel[MAX_DIMENSIONS], value, fill_value;
Real r_cum, g_cum, b_cum, a_cum;
Real r_cc, g_cc, b_cc, a_cc, weight;
Real r_light, g_light, b_light, dist;
Real r_object, g_object, b_object, a_object, opacity;
Real r_behind, g_behind, b_behind, a_behind;
Real dx, dy, dz;
Volume volume;
Surfprop spr;
BOOLEAN using_volume, hit_something;
hit_something = ray_intersects_objects( origin, direction,
n_objects, objects, use_flags,
&object_index, &intersection_point, &normal,
&object_colour, &spr, &dist );
if( hit_something )
{
if( objects[object_index].render.hit_only_once_flag )
use_flags[object_index] = FALSE;
using_volume = FALSE;
if( objects[object_index].regular_object_flag &&
objects[object_index].render.n_volumes > 0 )
{
r_cum = 0.0;
g_cum = 0.0;
b_cum = 0.0;
a_cum = 0.0;
for_less( v, 0, objects[object_index].render.n_volumes )
{
volume = objects[object_index].render.volumes[v].volume;
convert_3D_world_to_voxel( volume,
(Real) Point_x(intersection_point),
(Real) Point_y(intersection_point),
(Real) Point_z(intersection_point),
&voxel[X], &voxel[Y], &voxel[Z] );
if( voxel_is_within_volume( volume, voxel ) ||
objects[object_index].render.volumes[v].extend_volume_flag )
{
if( objects[object_index].render.volumes[v].
fill_value_specified )
{
fill_value = objects[object_index].render.volumes[v].
fill_value;
}
else
{
fill_value = get_volume_real_min(volume);
}
if( objects[object_index].render.volumes[v].gradient_flag )
{
evaluate_volume_in_world(
volume,
(Real) Point_x(intersection_point),
(Real) Point_y(intersection_point),
(Real) Point_z(intersection_point),
objects[object_index].render.volumes[v].
continuity,
FALSE,
fill_value,
&value, &dx, &dy, &dz,
NULL, NULL, NULL, NULL, NULL, NULL );
value = sqrt( dx * dx + dy * dy + dz * dz );
}
else
{
(void) evaluate_volume( volume, voxel, NULL,
objects[object_index].render.volumes[v].
continuity,
FALSE, fill_value,
&value, NULL, NULL );
}
if( is_an_rgb_volume( volume ) )
col_code = (Colour) value;
else
{
col_code = get_colour_code( &objects[object_index].
render.volumes[v].colour_coding, value );
}
opacity = objects[object_index].render.volumes[v].opacity;
r_cc = get_Colour_r_0_1( col_code );
g_cc = get_Colour_g_0_1( col_code );
b_cc = get_Colour_b_0_1( col_code );
a_cc = opacity * get_Colour_a_0_1( col_code );
weight = (1.0 - a_cc) * a_cum;
r_cum = weight * r_cum + a_cc * r_cc;
g_cum = weight * g_cum + a_cc * g_cc;
b_cum = weight * b_cum + a_cc * b_cc;
a_cum = weight + a_cc;
if( a_cum > 0.0 )
{
r_cum /= a_cum;
g_cum /= a_cum;
b_cum /= a_cum;
}
using_volume = TRUE;
}
}
if( using_volume )
{
if( objects[object_index].render.mult_volume_flag )
{
r_object = get_Colour_r_0_1( object_colour );
g_object = get_Colour_g_0_1( object_colour );
b_object = get_Colour_b_0_1( object_colour );
a_object = get_Colour_a_0_1( object_colour );
r_cum *= r_object;
g_cum *= g_object;
b_cum *= b_object;
a_cum *= a_object;
object_colour = make_rgba_Colour_0_1(
r_cum, g_cum, b_cum, a_cum );
}
else if( objects[object_index].render.composite_volume_flag )
{
cum_col = make_rgba_Colour_0_1( r_cum, g_cum, b_cum, a_cum);
COMPOSITE_COLOURS( object_colour, cum_col, object_colour );
}
else
{
object_colour = make_rgba_Colour_0_1(
r_cum, g_cum, b_cum, a_cum );
}
}
}
if( !objects[object_index].render.lighting_flag )
{
*r = get_Colour_r_0_1( object_colour );
*g = get_Colour_g_0_1( object_colour );
*b = get_Colour_b_0_1( object_colour );
*a = get_Colour_a_0_1( object_colour );
}
else
{
if( DOT_VECTORS( normal, *direction ) > 0.0 )
SCALE_VECTOR( normal, normal, -1.0 );
r_object = get_Colour_r_0_1( object_colour );
g_object = get_Colour_g_0_1( object_colour );
b_object = get_Colour_b_0_1( object_colour );
*a = (Real) Surfprop_t(spr) * get_Colour_a_0_1(object_colour);
*r = r_object * get_Colour_r_0_1( lights->ambient_light ) *
(Real) Surfprop_a(spr);
*g = g_object * get_Colour_g_0_1( lights->ambient_light ) *
(Real) Surfprop_a(spr);
*b = b_object * get_Colour_b_0_1( lights->ambient_light ) *
(Real) Surfprop_a(spr);
for_less( i, 0, lights->n_lights )
{
get_light_component( n_objects, objects,
&lights->lights[i],
objects[object_index].render.shadow_state,
objects[object_index].render.shadow_offset,
direction,
&intersection_point, &normal, &spr,
r_object, g_object, b_object,
&r_light, &g_light, &b_light );
*r += r_light;
*g += g_light;
*b += b_light;
}
}
if( *a < 1.0 )
{
SCALE_VECTOR( offset, *direction, dist +
objects[object_index].render.shadow_offset );
ADD_POINT_VECTOR( new_origin, *origin, offset );
if( recursive_ray_trace_one( &new_origin, direction,
lights, n_objects, objects, use_flags,
max_depth - 1,
&r_behind, &g_behind, &b_behind,
&a_behind ) )
{
weight = (1.0 - *a) * a_behind;
*r = weight * r_behind + *a * (*r);
*g = weight * g_behind + *a * (*g);
*b = weight * b_behind + *a * (*b);
*a = weight + *a;
if( *a > 0.0 )
{
r_cum /= *a;
g_cum /= *a;
b_cum /= *a;
}
}
}
}
return( hit_something );
}
public Colour trace_ray(
view_struct *view,
lights_struct *lights,
int n_objects,
ray_trace_object objects[],
BOOLEAN use_flags[],
int x_pixel,
int y_pixel,
int max_depth,
int x_super_sampling,
int y_super_sampling )
{
Real r_sum, g_sum, b_sum, a_sum, r, g, b, a, x_sub_pixel, y_sub_pixel;
int x, y, o;
Colour col;
Point origin;
Vector direction;
r_sum = 0.0;
g_sum = 0.0;
b_sum = 0.0;
a_sum = 0.0;
for_less( x, 0, x_super_sampling )
{
x_sub_pixel = (Real) x_pixel - 0.5 + ((Real) x + 0.5) /
(Real) x_super_sampling;
for_less( y, 0, y_super_sampling )
{
y_sub_pixel = (Real) y_pixel - 0.5 + ((Real) y + 0.5) /
(Real) y_super_sampling;
get_ray( view, x_sub_pixel, y_sub_pixel, &origin, &direction );
for_less( o, 0, n_objects )
use_flags[o] = TRUE;
if( recursive_ray_trace_one( &origin, &direction,
lights, n_objects, objects, use_flags,
max_depth, &r, &g, &b, &a ) )
{
r_sum += r * a;
g_sum += g * a;
b_sum += b * a;
a_sum += a;
}
}
}
if( x_super_sampling != 1 || y_super_sampling != 1 )
{
if( a_sum > 0.0 )
{
r_sum /= a_sum;
g_sum /= a_sum;
b_sum /= a_sum;
a_sum /= (Real) (x_super_sampling * y_super_sampling);
}
}
if( r_sum < 0.0 )
r_sum = 0.0;
else if( r_sum > 1.0 )
r_sum = 1.0;
if( g_sum < 0.0 )
g_sum = 0.0;
else if( g_sum > 1.0 )
g_sum = 1.0;
if( b_sum < 0.0 )
b_sum = 0.0;
else if( b_sum > 1.0 )
b_sum = 1.0;
if( a_sum < 0.0 )
a_sum = 0.0;
else if( a_sum > 1.0 )
a_sum = 1.0;
col = make_rgba_Colour_0_1( r_sum, g_sum, b_sum, a_sum );
return( col );
}
private void ray_trace_scanline(
view_struct *view,
lights_struct *lights,
int n_objects,
ray_trace_object objects[],
int max_depth,
int x_super_sampling,
int y_super_sampling,
int y,
pixels_struct *pixels )
{
int x;
BOOLEAN *use_flags;
ALLOC( use_flags, n_objects );
for_less( x, 0, view->x_viewport_size )
{
PIXEL_RGB_COLOUR( *pixels, x, y ) = trace_ray( view, lights,
n_objects, objects, use_flags, x, y,
max_depth,
x_super_sampling, y_super_sampling );
}
FREE( use_flags );
}
typedef struct
{
view_struct *view;
lights_struct *lights;
int n_objects;
ray_trace_object *objects;
int max_depth;
int x_super_sampling;
int y_super_sampling;
int y;
int y_increment;
int y_size;
pixels_struct *pixels;
} scan_line_struct;
private void ray_trace_a_scanline(
int y,
void *data)
{
int y_start, y_end;
scan_line_struct *scan_data;
scan_data = (scan_line_struct *) data;
y_start = y;
y_end = MIN( y + scan_data->y_increment, scan_data->y_size );
for_less( y, y_start, y_end )
{
ray_trace_scanline( scan_data->view,
scan_data->lights,
scan_data->n_objects,