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removed the ERROR_COLOUR macro
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removed a useless case where ERROR_COLOUR is returned when no object intersection is found from pixel_colour_from_ray()
changed nearest_object_intersecting_ray() to deal with different return values from ray_object_intersect()
moved hitlocation and hitnormal calculations into specific ray_object_intersect() functions
changed the default return value of ray_object_intersect() to none
removed object_normal_at_point() and related tests
changed from infinity to none as return value of the intersection functions when no intersetion is found


git-svn-id: http://svn.plouj.com/repos/eraytracer@59 b8c14938-b733-429d-887c-d66ed1f8cd15
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plouj committed Feb 15, 2008
1 parent 6645b36 commit 531a706
Showing 1 changed file with 63 additions and 88 deletions.
151 changes: 63 additions & 88 deletions raytracer.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,6 @@
-record(plane, {normal, distance, material}).
-record(point_light, {diffuse_colour, location, specular_colour}).
-define(BACKGROUND_COLOUR, #colour{r=0, g=0, b=0}).
-define(ERROR_COLOUR, #colour{r=1, g=0, b=0}).
-define(UNKNOWN_COLOUR, #colour{r=0, g=1, b=0}).
-define(FOG_DISTANCE, 40).

Expand Down Expand Up @@ -197,10 +196,8 @@ pixel_colour_from_ray(Ray, Scene, Recursion_depth) ->
Hit_normal,
Scene,
Recursion_depth));
none ->
?BACKGROUND_COLOUR;
_Else ->
?ERROR_COLOUR
?BACKGROUND_COLOUR
end.

% my own illumination formula
Expand Down Expand Up @@ -326,31 +323,36 @@ nearest_object_intersecting_ray(Ray,
Normal,
Distance,
[CurrentObject|Rest_of_scene]) ->
NewDistance = ray_object_intersect(Ray, CurrentObject),
%io:format("Distace=~w NewDistace=~w~n", [Distance, NewDistance]),
if (NewDistance /= infinity)
and ((Distance == infinity) or (Distance > NewDistance)) ->
%io:format("another closer object found~n", []),
New_hit_location =
vector_add(Ray#ray.origin,
vector_scalar_mult(Ray#ray.direction, NewDistance)),
New_normal = object_normal_at_point(
CurrentObject, New_hit_location),
case ray_object_intersect(Ray, CurrentObject) of
{NewDistance, New_hit_location, New_normal} ->
%io:format("Distace=~w NewDistace=~w~n", [Distance, NewDistance]),
if (Distance == infinity) or (Distance > NewDistance) ->
%io:format("another closer object found~n", []),
nearest_object_intersecting_ray(
Ray,
CurrentObject,
New_hit_location,
New_normal,
NewDistance,
Rest_of_scene);
true ->
%io:format("no closer obj found~n", []),
nearest_object_intersecting_ray(
Ray,
NearestObj,
Hit_location,
Normal,
Distance,
Rest_of_scene)
end;
none ->
nearest_object_intersecting_ray(
Ray,
CurrentObject,
New_hit_location,
New_normal,
NewDistance,
Rest_of_scene);
true ->
%io:format("no closer obj found~n", []),
nearest_object_intersecting_ray(Ray,
NearestObj,
Hit_location,
Normal,
Distance,
Rest_of_scene)
NearestObj,
Hit_location,
Normal,
Distance,
Rest_of_scene)
end.

% object specific intersection function
Expand All @@ -363,18 +365,9 @@ ray_object_intersect(Ray, Object) ->
#plane{} ->
ray_plane_intersect(Ray, Object);
_Else ->
infinity
none
end.

object_normal_at_point(#sphere{center=Center}, Point) ->
vector_normalize(
vector_sub(Point, Center));
object_normal_at_point(#plane{normal=Normal}, _Point) ->
Normal;
object_normal_at_point(#triangle{v1=V1,v2=V2}, _Point) ->
vector_normalize(
vector_cross_product(V1, V2)).

% based on
% http://www.devmaster.net/articles/raytracing/
% http://www.siggraph.org/education/materials/HyperGraph/raytrace/rtinter1.htm
Expand All @@ -397,12 +390,20 @@ ray_sphere_intersect(
T1 = (-B - math:sqrt(Discriminant))/2,
if (T0 >= 0) and (T1 >= 0) ->
%io:format("T0=~w T1=~w~n", [T0, T1]),
lists:min([T0, T1]);
Distance = lists:min([T0, T1]),
Intersection = vector_add(
#vector{x=X0, y=Y0, z=Z0},
vector_scalar_mult(
#vector{x=Xd, y=Yd, z=Zd}, Distance)),
Normal = vector_normalize(
vector_sub(Intersection,
#vector{x=Xc, y=Yc, z=Zc})),
{Distance, Intersection, Normal};
true ->
infinity
none
end;
true ->
infinity
none
end.

% based on
Expand All @@ -425,7 +426,7 @@ ray_triangle_intersect(Ray, Triangle) ->
if Determinant < Epsilon ->
% for our purposes we ignore such triangles
%% io:format("ray is either behind or on the triangle: ~p~n", [Determinant]),
infinity;
none;
true ->
% calculate the distance from v1 to ray origin
T = vector_sub(Ray#ray.origin, Triangle#triangle.v1),
Expand All @@ -434,7 +435,7 @@ ray_triangle_intersect(Ray, Triangle) ->
U = vector_dot_product(T, P),
if (U < 0) or (U > Determinant) ->
%% io:format("U is negative or greater than det: ~p~n", [U]),
infinity;
none;
true ->
% prepare to test the V parameter
Q = vector_cross_product(T, Edge1),
Expand All @@ -443,12 +444,22 @@ ray_triangle_intersect(Ray, Triangle) ->
if (V < 0) or (U+V > Determinant) ->
%% io:format("V less than 0.0 or U+V greater than det: ~p ~p~n",
%% [U, V]),
infinity;
none;
true ->
% calculate the distance to the
% intersection point and return
%% io:format("found ray/triangle intersection ~n", []),
vector_dot_product(Edge2, Q) / Determinant
Distance = vector_dot_product(Edge2, Q) / Determinant,
Intersection = vector_add(
Ray#ray.origin,
vector_scalar_mult(
Ray#ray.direction,
Distance)),
Normal = vector_normalize(
vector_sub(
Triangle#triangle.v1,
Triangle#triangle.v2)),
{Distance, Intersection, Normal}
end
end
end.
Expand All @@ -465,12 +476,17 @@ ray_plane_intersect(Ray, Plane) ->
+ Plane#plane.distance),
Distance = V0 / Vd,
if Distance < Epsilon ->
infinity;
none;
true ->
Distance
Intersection = vector_add(
Ray#ray.origin,
vector_scalar_mult(
Ray#ray.direction,
Distance)),
{Distance, Intersection, Plane#plane.normal}
end;
true ->
infinity
none
end.


Expand Down Expand Up @@ -658,7 +674,6 @@ scene() ->
reflectivity=0.01}}
].


% assumes Pixels are ordered in a row by row fasion
write_pixels_to_ppm(Width, Height, MaxValue, Pixels, Filename) ->
case file:open(Filename, write) of
Expand Down Expand Up @@ -747,7 +762,6 @@ run_tests() ->
fun nearest_object_intersecting_ray_test/0,
fun focal_length_test/0,
% fun vector_rotation_test/0,
fun object_normal_at_point_test/0,
fun vector_bounce_off_plane_test/0,
fun ray_sphere_intersection_test/0
],
Expand Down Expand Up @@ -1107,45 +1121,6 @@ focal_length_test() ->
end, true,
[{13, 108}, {15, 100.4}, {18, 90}, {21, 81.2}]).

object_normal_at_point_test() ->
io:format("object normal at point test"),
Sphere1 = #sphere{radius=13.5,
center=#vector{x=0, y=0, z=0},
material=#material{
colour=#colour{r=0, g=0, b=0}}},
Point1 = #vector{x=13.5, y=0, z=0},
Point2 = #vector{x=0, y=13.5, z=0},
Point3 = #vector{x=0, y=0, z=13.5},
Point4 = vector_neg(Point1),
Point5 = vector_neg(Point2),
Point6 = vector_neg(Point3),

% sphere object tests
Subtest1 = vectors_equal(
vector_normalize(Point1),
object_normal_at_point(Sphere1, Point1)),
Subtest2 = vectors_equal(
vector_normalize(Point2),
object_normal_at_point(Sphere1, Point2)),
Subtest3 = vectors_equal(
vector_normalize(Point3),
object_normal_at_point(Sphere1, Point3)),
Subtest4 = vectors_equal(
vector_normalize(Point4),
object_normal_at_point(Sphere1, Point4)),
Subtest5 = vectors_equal(
vector_normalize(Point5),
object_normal_at_point(Sphere1, Point5)),
Subtest6 = vectors_equal(
vector_normalize(Point6),
object_normal_at_point(Sphere1, Point6)),
Subtest7 = not vectors_equal(
vector_normalize(Point1),
object_normal_at_point(Sphere1, Point4)),

Subtest1 and Subtest2 and Subtest3 and Subtest4 and Subtest5 and Subtest6
and Subtest7.

vector_bounce_off_plane_test() ->
io:format("vector reflect about normal", []),
Vector1 = #vector{x=1, y=1, z=0},
Expand Down

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