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| ALLEGRO 5 - Bitmap Corruption after writing to source image |
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Kev Callahan
Member #6,022
July 2005
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I'm currently messing around with ALLEGRO 5 on an ARM chip (iMX6). I found this initially whilst using al_convert_mask_to_alpha() converting magic pink to transparency. The issue is that if I have an ALLEGRO_BITMAP and drawing it straight to the display everything's fine. However if I write to this BITMAP using al_convert_mask_to_alpha() or even if I draw another smaller BITMAP onto it, then it appears to corrupt the original image. Setting a single pixel on the image doesn't appear to have any corruption effect.. Any ideas on how I best investigate this to track down the error? EDIT: bmp1 is 200x200 Load bmp1 and leave as is - drawn okay on display. EDIT2: |
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Elias
Member #358
May 2000
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Could also be a bug in OpenGL drivers - but more likely in Allegro. Can you post a minimal program reproducing it? -- |
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Kev Callahan
Member #6,022
July 2005
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As requested (pardon the hastily stripped down source), also attached the two source images, screenshot showing corruption and allegro.log tried with 24bit and 32 bit source images - same issue. Thanks. 1#include <stdio.h>
2#include <stdlib.h>
3#include <math.h>
4#include <signal.h>
5#include <ctype.h>
6
7#include <allegro5/allegro.h>
8#include <allegro5/allegro_image.h>
9#include <allegro5/allegro_font.h>
10#include <allegro5/allegro_ttf.h>
11#include <allegro5/allegro_primitives.h>
12#include <allegro5/allegro_opengl.h>
13#include <allegro5/allegro_image.h>
14
15#include "header.h"
16#include "font.h"
17#include "button.h"
18
19int winsize_x = 640;
20int winsize_y = 480;
21
22ALLEGRO_DISPLAY *display = NULL;
23
24#define HZTIMER 30
25
26ALLEGRO_BITMAP *bmp1, *bmp2, *bmp3;
27
28// **
29int main(int argc, char **argv)
30{
31 int drawpage=0, mouse_x=0, mouse_y=0;
32 char inifile[32] = {0};
33
34 ALLEGRO_TIMER *timer = NULL;
35 ALLEGRO_EVENT_QUEUE *eventq = NULL;
36 ALLEGRO_KEYBOARD_STATE *kbdstate = NULL;
37 ALLEGRO_MOUSE_STATE *mousestate = NULL;
38
39 // ** allegro initialisation
40 {
41 if (! al_init()) { fprintf(stderr, "Failed to initialise ALLEGRO\n"); return -1; }
42
43 // input
44 if (! al_install_keyboard()) { WHERE(); }
45 if (! al_install_mouse ()) { WHERE(); }
46
47 // addons
48 al_init_image_addon();
49 al_init_font_addon();
50 al_init_ttf_addon();
51 al_init_primitives_addon();
52 }
53
54 // ** create default path for resources
55 {
56 ALLEGRO_PATH *path = al_get_standard_path(ALLEGRO_RESOURCES_PATH);
57 al_append_path_component(path, "resources");
58 al_change_directory(al_path_cstr(path, '/'));
59 fprintf(stderr, "PATH: %s\n", al_path_cstr(path, '/'));
60 al_destroy_path(path);
61 }
62
63 // ** setup display
64 {
65 al_set_new_display_flags (ALLEGRO_OPENGL);
66 al_set_new_display_option(ALLEGRO_SAMPLE_BUFFERS, 1, ALLEGRO_SUGGEST);
67 al_set_new_display_option(ALLEGRO_SAMPLES, 8, ALLEGRO_SUGGEST);
68
69 display = al_create_display(winsize_x, winsize_y);
70
71 printf("OPENGL VERSION %x\n", al_get_opengl_version());
72 printf("OPENGL VARIANT %x\n", al_get_opengl_variant());
73
74 if (! display) { fprintf(stderr, "failed to create display %dx%d\n", winsize_x, winsize_y); return -1; }
75
76 fprintf(stderr, "Created Display %dx%d\n", winsize_x, winsize_y);
77
78 al_set_window_title(display, "SIMPLE");
79 }
80
81 // clear display
82 {
83 al_set_target_backbuffer(display);
84 al_clear_to_color(al_map_rgb(12,13,18));
85 }
86
87 bmp1 = al_load_bitmap("200x200.png");
88 bmp2 = al_load_bitmap("200x200.png");
89 bmp3 = al_load_bitmap("20x20.png");
90
91 //al_convert_mask_to_alpha(bmp2, al_map_rgb(255,0,255)); // magic pink is transparent
92
93 // cause bug - draw bmp3 onto bmp2
94 {
95 al_set_target_bitmap(bmp2);
96 al_draw_bitmap(bmp3, 50, 50, 0);
97 }
98
99 al_set_target_backbuffer(display);
100
101
102 eventq = al_create_event_queue();
103
104 // ** loop
105 while (1)
106 {
107 // ** draw on display
108 {
109 al_set_target_backbuffer(display);
110 al_draw_bitmap(bmp1, 0, 0, 0);
111 al_draw_bitmap(bmp2, 320, 0, 0);
112 }
113
114 al_flip_display();
115
116 }
117
118 // ** shutdown
119 {
120 al_destroy_display(display);
121 }
122
123 return 0;
124}
EDIT: Much more investigation today - I'm now thinking there are driver issues (maybe I need to do something like Trent did for the Raspberry Pi to get Allegro working on this card, but quite frankly that's beyond me). To summarise, it appears that loading a bitmap and displaying on the screen appears to work, but as soon as I read or write access that bitmap (eg with al_get_pixel()), the image reverts to an 'old' version that's cached somewhere... (in the GPU?) from previously (demonstrated by changing the images used). |
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