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| example of code for al_draw_ribbon, al_calculate_spline/ribbon |
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Fred58
Member #11,939
May 2010
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hello, i'm looking for examples of code for functions because i don't understand the void al_draw_ribbon(const float *points, int points_stride, ALLEGRO_COLOR color, void al_calculate_ribbon(float* dest, int dest_stride, const float *points, void al_calculate_spline(float* dest, int stride, float points[8], Thank very much |
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SiegeLord
Member #7,827
October 2006
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Here's a quick example. I note that num_segments is a wrong name for that parameter: it should be num_corners or num_points perhaps. The stride parameters allow you to use structs that are not just pairs of floats when the functions ask for points. 1#include <allegro5/allegro.h>
2#include <allegro5/allegro_primitives.h>
3
4int main()
5{
6 al_init();
7 al_init_primitives_addon();
8 auto disp = al_create_display(800, 600);
9 auto queue = al_create_event_queue();
10 al_register_event_source(queue, al_get_display_event_source(disp));
11 al_clear_to_color(al_map_rgb_f(0, 0, 0));
12
13 struct MyPoint
14 {
15 float x, y;
16 int something_else;
17 };
18
19 const size_t num_points1 = 5;
20 MyPoint points1[5] =
21 {
22 {100, 100, 0},
23 {100, 150, 0},
24 {200, 200, 0},
25 {200, 300, 0},
26 {100, 500, 0}
27 };
28
29 al_draw_ribbon((float*)points1, sizeof(MyPoint), al_map_rgb_f(1, 0, 0.5), 10, num_points1);
30
31 const size_t num_points2 = num_points1 * 2;
32 auto points2 = new MyPoint[num_points2];
33
34 al_calculate_ribbon((float*)points2, sizeof(MyPoint), (float*)points1, sizeof(MyPoint), 30, num_points1);
35
36 for(size_t ii = 0; ii < num_points2; ii++)
37 al_draw_filled_circle(points2[ii].x, points2[ii].y, 5, al_map_rgb_f(1, 0.5, 0));
38
39 float spline_control_points[8] =
40 {
41 400, 100,
42 500, 200,
43 300, 400,
44 400, 500
45 };
46
47 al_calculate_spline((float*)points2, sizeof(MyPoint), spline_control_points, 30, num_points1);
48
49 for(size_t ii = 0; ii < num_points2; ii++)
50 al_draw_filled_circle(points2[ii].x, points2[ii].y, 5, al_map_rgb_f(0.5, 1, 0));
51
52 al_flip_display();
53 ALLEGRO_EVENT ev;
54 al_wait_for_event(queue, &ev);
55
56 delete[] points2;
57}
"For in much wisdom is much grief: and he that increases knowledge increases sorrow."-Ecclesiastes 1:18 |
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Fred58
Member #11,939
May 2010
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Thank you very much for this example of code. |
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