1/* Create a skybox. This is simply 5 quads with a fixed distance to the
2* camera.
3*/
4static void add_skybox
(void)
5{
6 Vector pos
= starfield.camera.position
;
7 ALLEGRO_COLOR color1
= al_color_name("black");
8 ALLEGRO_COLOR color2
= al_color_name("blue");
9 ALLEGRO_COLOR color3
= al_color_name("white");
10
11 double tex_size
= 0;
12 if (starfield.front
) {
13 tex_size
= al_get_bitmap_width(starfield.front
);
14 color1
= color2
= color3
;
15 }
16
17 // x1,y1,z1,u1,v1
18 // x2,y2,z2,u2,v2
19 // x3,y3,z3,u3,v3
20 // color tri, color tri2
21
22 /* Front skybox wall. */
23 add_quad
(-50,
-50,
-50, tex_size,
0,
24 100,
0,
0,
-tex_size,
0,
25 0,
100,
0,
0,
-tex_size,
26 color1, color2
);
27
28
29 /* Right skybox wall. */
30 add_quad
(50,
-50,
-50, tex_size,
0,
31 0,
0,
100,
-tex_size,
0,
32 0,
100,
0,
0,
-tex_size,
33 color1, color2
);
34
35 /* Back skybox wall. */
36 add_quad
(-50,
-50,
50,
0, tex_size,
37 100,
0,
0, tex_size,
0,
38 0,
100,
0,
0,
-tex_size,
39 color1, color2
);
40
41 /* Left skybox wall. */
42 add_quad
(-50,
-50,
-50,
0, tex_size,
43 0,
0,
100, tex_size,
0,
44 0,
100,
0,
0,
-tex_size,
45 color1, color2
);
46
47 //These were added on a per-vertex basis
48 //x,y,z,u,v,color
49
50 /* Top skybox wall. */
51 add_vertex
(-50,
50,
-50,
0,
0, color2
);
52 add_vertex
(50,
50,
-50,
-tex_size,
0, color2
);
53 add_vertex
(50,
50,
50,
-tex_size,
-tex_size, color2
);
54
55 add_vertex
(50,
50,
50,
-tex_size,
-tex_size, color2
);
56 add_vertex
(-50,
50,
50,
0,
-tex_size, color2
);
57 add_vertex
(-50,
50,
-50,
0,
0, color2
);
58
59
60 /* Bottom skybox wall. */
61
62 add_vertex
(-50,
-50,
50,
0,
0, color2
);
63 add_vertex
(50,
-50,
50,
-tex_size,
-0, color2
);
64 add_vertex
(50,
-50,
-50,
-tex_size,
-tex_size, color2
);
65
66 add_vertex
(50,
-50,
-50,
-tex_size,
-tex_size, color2
);
67 add_vertex
(-50,
-50,
-50,
0,
-tex_size, color2
);
68 add_vertex
(-50,
-50,
50,
0,
0, color2
);
69
70
71}
72
73static void draw_scene
(void)
74{
75 Camera
*c
= &starfield.camera
;
76 /* We save Allegro's projection so we can restore it for drawing text. */
77 ALLEGRO_TRANSFORM projection
= *al_get_current_projection_transform
();
78 ALLEGRO_TRANSFORM t
;
79 ALLEGRO_COLOR back
= al_color_name("black");
80 ALLEGRO_COLOR front
= al_color_name("white");
81 int th
;
82 double pitch, yaw, roll
;
83
84 setup_3d_projection
();
85 al_clear_to_color(back
);
86
87 /* We use a depth buffer. */
88 al_set_render_state
(ALLEGRO_DEPTH_TEST,
1);
89 al_clear_depth_buffer
(1);
90
91 /* Recreate the entire scene geometry - this is only a very small example
92 * so this is fine.
93 */
94 starfield.n
= 0;
95
96 add_skybox
();
97
98 /* Construct a transform corresponding to our camera. This is an inverse
99 * translation by the camera position, followed by an inverse rotation
100 * from the camera orientation.
101 */
102 al_build_camera_transform
(&t,
103 starfield.camera.position.x, starfield.camera.position.y, starfield.camera.position.z,
104 starfield.camera.position.x
- starfield.camera.zaxis.x,
105 starfield.camera.position.y
- starfield.camera.zaxis.y,
106 starfield.camera.position.z
- starfield.camera.zaxis.z,
107 starfield.camera.yaxis.x, starfield.camera.yaxis.y, starfield.camera.yaxis.z
);
108 al_use_transform(&t
);
109
110 al_draw_prim(starfield.v, NULL, starfield.front,
0,
3, ALLEGRO_PRIM_TRIANGLE_LIST
); //front
111 al_draw_prim(starfield.v, NULL, starfield.front,
3,
6, ALLEGRO_PRIM_TRIANGLE_LIST
); //front
112 al_draw_prim(starfield.v, NULL, starfield.right,
6,
9, ALLEGRO_PRIM_TRIANGLE_LIST
); //right
113 al_draw_prim(starfield.v, NULL, starfield.right,
9,
12, ALLEGRO_PRIM_TRIANGLE_LIST
); //right
114 al_draw_prim(starfield.v, NULL, starfield.back,
12,
15, ALLEGRO_PRIM_TRIANGLE_LIST
); //back
115 al_draw_prim(starfield.v, NULL, starfield.back,
15,
18, ALLEGRO_PRIM_TRIANGLE_LIST
); //back
116 al_draw_prim(starfield.v, NULL, starfield.left,
18,
21, ALLEGRO_PRIM_TRIANGLE_LIST
); //left
117 al_draw_prim(starfield.v, NULL, starfield.left,
21,
24, ALLEGRO_PRIM_TRIANGLE_LIST
); //left
118 al_draw_prim(starfield.v, NULL, starfield.up,
24,
27, ALLEGRO_PRIM_TRIANGLE_LIST
); //up
119 al_draw_prim(starfield.v, NULL, starfield.up,
27,
30, ALLEGRO_PRIM_TRIANGLE_LIST
); //up
120 al_draw_prim(starfield.v, NULL, starfield.down,
30,
33, ALLEGRO_PRIM_TRIANGLE_LIST
); //down
121 al_draw_prim(starfield.v, NULL, starfield.down,
33,
36, ALLEGRO_PRIM_TRIANGLE_LIST
); //down
122
123
124 /* Restore projection. */
125 al_identity_transform(&t
);
126 al_use_transform(&t
);
127 al_use_projection_transform
(&projection
);
128 al_set_render_state
(ALLEGRO_DEPTH_TEST,
0);
129}
