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| Allegro color bitmap |
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WielkiB
Member #19,906
April 2021
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I got a snake head like this, and now I'm looking for something that I can use to make ONLY white color different. I though 'tinted bitmap' would be good, but it's also coloring eyes, and tongue. Furthermore, I found al_get_pixel and al_put_pixel, but in this I need to give x and y of pixel, so it's difficult to make it with that bitmap |
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Arthur Kalliokoski
Second in Command
February 2005
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al_get_pixel returns an ALLEGRO_COLOR, so run through all the x/y combinations and check if that color is white. If it is, use al_put_pixel on that same x/y with the replacement color and when you're done, save the png. They all watch too much MSNBC... they get ideas. |
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WielkiB
Member #19,906
April 2021
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Am I must save bitmap as .png file? If I want to do it in .png I will color it in Inkscape and then export |
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Peter Hull
Member #1,136
March 2001
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I would:
you can do this on an offscreen bitmap and then re-use that bitmap [edit] hm, that doesn't work if you want the surroundings of the head to be transparent. 1#include <allegro5/allegro.h>
2#include <allegro5/allegro_image.h>
3
4ALLEGRO_BITMAP *make_snake(ALLEGRO_BITMAP *s, ALLEGRO_COLOR c) {
5 int w = al_get_bitmap_width(s);
6 int h = al_get_bitmap_height(s);
7 ALLEGRO_BITMAP *b = al_create_bitmap(w, h);
8 al_set_target_bitmap(b);
9 al_clear_to_color(c);
10 al_draw_bitmap(s, 0.0f, 0.0f, 0);
11 al_set_target_backbuffer(al_get_current_display());
12 return b;
13}
14int main() {
15 al_init();
16 al_init_image_addon();
17 ALLEGRO_DISPLAY *d = al_create_display(640, 480);
18 ALLEGRO_BITMAP *snake = al_load_bitmap("snake_white.png");
19 ALLEGRO_BITMAP *snakes[3];
20 ALLEGRO_COLOR cs[] = {al_map_rgb(255, 128, 128), al_map_rgb(128, 255, 128),
21 al_map_rgb(128, 128, 255)};
22 int i;
23 for (i = 0; i < 3; ++i) {
24 snakes[i] = make_snake(snake, cs[i]);
25 }
26 al_clear_to_color(al_map_rgb(255, 255, 255));
27 for (i = 0; i < 3; ++i) {
28 al_draw_bitmap(snakes[i], 200.0f * i, 100.0f, 0);
29 }
30 al_flip_display();
31 al_rest(10.0);
32 return 0;
33}
[edit2] Better but I had to split the snake into two layers (you will be able to do this better if you have the original vector image!) (see attachments) 1#include <allegro5/allegro.h>
2#include <allegro5/allegro_image.h>
3
4ALLEGRO_BITMAP *make_snake2(ALLEGRO_BITMAP *f, ALLEGRO_BITMAP *k,
5 ALLEGRO_COLOR c) {
6 int w = al_get_bitmap_width(k);
7 int h = al_get_bitmap_height(k);
8 ALLEGRO_BITMAP *b = al_create_bitmap(w, h);
9 al_set_target_bitmap(b);
10 al_clear_to_color(al_map_rgba(255,255,255,0));
11 al_draw_tinted_bitmap(k, c, 0.0f, 0.0f, 0);
12 al_draw_bitmap(f, 0.0f, 0.0f, 0);
13 al_set_target_backbuffer(al_get_current_display());
14 return b;
15}
16
17int main() {
18 al_init();
19 al_init_image_addon();
20 ALLEGRO_DISPLAY *d = al_create_display(640, 480);
21 ALLEGRO_BITMAP *front = al_load_bitmap("front.png");
22 ALLEGRO_BITMAP *back = al_load_bitmap("back.png");
23 ALLEGRO_BITMAP *snakes[3];
24 ALLEGRO_COLOR cs[] = {al_map_rgb(255, 128, 128), al_map_rgb(128, 255, 128),
25 al_map_rgb(128, 128, 255)};
26 int i;
27 for (i = 0; i < 3; ++i) {
28 snakes[i] = make_snake2(front, back, cs[i]);
29 }
30 al_clear_to_color(al_map_rgb(255, 255, 255));
31 for (i = 0; i < 3; ++i) {
32 al_draw_bitmap(snakes[i], 200.0f * i, 100.0f, 0);
33 }
34 al_flip_display();
35 al_rest(10.0);
36 return 0;
37}
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RmBeer2
Member #16,660
April 2017
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you can read about al_lock_bitmap/al_unlock_bitmap, This function allows you to access the bitmap directly in memory and modify the colors of the pixels one by one. It's much faster if you know how. https://liballeg.org/a5docs/trunk/graphics.html#al_lock_bitmap 🌈🌈🌈 🌟 BlackRook WebSite (Only valid from my installer) 🌟 C/C++ 🌟 GNU/Linux 🌟 IceCream/Cornet 🌟 🌈🌈🌈 Rm Beer for Emperor 2021! Rm Beer for Ruinous Slave Drained 2022! Rm Beer for Traveler From The Future Warning Not To Enter In 2023! Rm Beer are building a travel machine for Go Back from 2023! Rm Beer in an apocalyptic world burning hordes of Zombies in 2024! |
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Dizzy Egg
Member #10,824
March 2009
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This should get you started, this loads your snake_white.png, then saves it as snake_green.bmp, which I have attached. You would obviously want to put this in a function, so you can use different colours etc, but this will get you started! 1int main()
2{
3 al_init();
4 al_init_primitives_addon();
5 al_init_image_addon();
6
7 ALLEGRO_DISPLAY *display = al_create_display(1024, 768);
8
9 ALLEGRO_BITMAP *snake_white = al_load_bitmap("snake_white.png");
10 ALLEGRO_BITMAP *snake_green = al_create_bitmap(al_get_bitmap_width(snake_white), al_get_bitmap_height(snake_white));
11 ALLEGRO_COLOR color;
12
13 al_set_target_bitmap(snake_green);
14
15 al_lock_bitmap(snake_white, ALLEGRO_LOCK_READONLY, 0);
16
17 for(int x=0; x<al_get_bitmap_width(snake_white); x++)
18 {
19 for(int y=0; y<al_get_bitmap_height(snake_white); y++)
20 {
21 color = al_get_pixel(snake_white, x, y);
22
23 if(color.r == 1.0 && color.g == 1.0 && color.b == 1.0)
24 {
25 al_put_pixel(x, y, al_map_rgb(50, 255, 50)); //Choose your own colour!
26 }
27 else
28 {
29 al_put_pixel(x, y, color);
30 }
31 }
32 }
33
34 al_unlock_bitmap(snake_white);
35 al_save_bitmap("snake_green.bmp", snake_green);
36}
---------------------------------------------------- |
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Peter Hull
Member #1,136
March 2001
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These getpixel/putpixel solutions aren't ever going to work well because of the grey pixels at the edge of the outlines (antialiasing isn't it?). Depends on the image, I guess it would be fine for pixel-art type images.
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Dizzy Egg
Member #10,824
March 2009
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Peter Hull said: (antialiasing isn't it?)
Yes, exactly! I did say "this should get you started" Some math would be required to properly colour those antialiased areas to the new colour, but I'm not going to provide that solution straight away [EDIT] 1#include <iostream>
2#include <allegro5/allegro.h>
3#include <allegro5/allegro_primitives.h>
4#include <allegro5/allegro_image.h>
5#include "stdio.h"
6
7using namespace std;
8
9ALLEGRO_DISPLAY *display;
10ALLEGRO_BITMAP *snake_white;
11
12void color_snake_and_save(ALLEGRO_COLOR new_color, const char *file_name)
13{
14 ALLEGRO_BITMAP *snake_new = al_create_bitmap(al_get_bitmap_width(snake_white), al_get_bitmap_height(snake_white));
15 ALLEGRO_COLOR color;
16
17 al_set_target_bitmap(snake_new);
18
19 al_lock_bitmap(snake_white, ALLEGRO_PIXEL_FORMAT_ANY_WITH_ALPHA, ALLEGRO_LOCK_READONLY);
20
21 for(int x=0; x<al_get_bitmap_width(snake_white); x++)
22 {
23 for(int y=0; y<al_get_bitmap_height(snake_white); y++)
24 {
25 color = al_get_pixel(snake_white, x, y);
26
27 if(color.r >= 0.01 && color.g >= 0.01 && color.b >= 0.01)
28 {
29 al_put_pixel(x, y, al_map_rgba_f(new_color.r * color.r, new_color.g * color.g, new_color.b * color.b, color.a));
30 }
31 else
32 {
33 al_put_pixel(x, y, color);
34 }
35 }
36 }
37
38 al_unlock_bitmap(snake_white);
39 al_save_bitmap(file_name, snake_new);
40
41 al_destroy_bitmap(snake_new);
42}
43
44int main()
45{
46 al_init();
47 al_init_primitives_addon();
48 al_init_image_addon();
49
50 display = al_create_display(1024, 768);
51
52 snake_white = al_load_bitmap("snake_white.png");
53
54 color_snake_and_save(al_map_rgb(255, 50, 50), "snake_red.bmp");
55 color_snake_and_save(al_map_rgb(50, 255, 50), "snake_green.bmp");
56 color_snake_and_save(al_map_rgb(50, 50, 255), "snake_blue.bmp");
57}
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So the thing I'm looking for is something like al_get_pixel but with given color, not x/y.
. I want to do in live in program. Like in MENU:
