With Allegro comes quite a bunch of examples, which go from the simple introductory `Hello world' to more complicated programs featuring truecolor blending effects. This chapter describes these examples which you can find in the allegro/examples folder. You don't have to go through them in the same order as this documentation, but doing so you will learn the basic functions and avoid missing any important bit of information.
See also: END_OF_MAIN, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, clear_to_color, desktop_palette, font, install_keyboard, key, makecol, readkey, release_screen, screen, set_gfx_mode, set_palette, textout_centre_ex.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, blit, circle, clear_bitmap, create_bitmap, desktop_palette, destroy_bitmap, install_keyboard, palette_color, readkey, release_screen, screen, set_gfx_mode, set_palette.
See also: END_OF_MAIN, PALETTE, RGB, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, black_palette, circlefill, install_keyboard, install_mouse, keypressed, release_screen, screen, set_gfx_mode, set_palette, show_mouse.
See also: BITMAP, END_OF_MAIN, acquire_bitmap, allegro_error, allegro_init, allegro_message, bitmap_mask_color, blit, clear_to_color, create_bitmap, create_sub_bitmap, desktop_palette, destroy_bitmap, drawing_mode, font, install_keyboard, makecol, masked_blit, palette_color, readkey, rectfill, release_bitmap, screen, set_gfx_mode, set_palette, solid_mode, text_height, text_length, textout_ex.
See also: END_OF_MAIN, PALETTE, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, bmp_read_line, bmp_unwrite_line, bmp_write_line, clear_keybuf, font, getpixel, install_keyboard, keypressed, line, makecol, putpixel, release_screen, rest, screen, set_gfx_mode, set_palette, textout_ex.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, blit, circlefill, clear_keybuf, clear_to_color, create_bitmap, desktop_palette, destroy_bitmap, font, install_keyboard, install_timer, keypressed, makecol, release_screen, retrace_count, screen, set_gfx_mode, set_palette, textprintf_ex.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, circlefill, clear_keybuf, clear_to_color, create_bitmap, create_video_bitmap, desktop_palette, destroy_bitmap, font, install_keyboard, install_timer, keypressed, makecol, retrace_count, screen, set_gfx_mode, set_palette, show_video_bitmap, textprintf_ex.
See also: END_OF_MAIN, allegro_init, allegro_message, fixdiv, fixed, fixmul, fixsqrt, fixtof, ftofix, itofix.
See also: END_OF_MAIN, FONT, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, clear_to_color, desktop_palette, destroy_font, extract_font_range, font, install_keyboard, key, load_font, makecol, merge_fonts, readkey, release_screen, screen, set_gfx_mode, set_palette, textout_centre_ex.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, bitmap_mask_color, circle, clear_keybuf, clear_to_color, create_bitmap, desktop_palette, destroy_bitmap, font, get_mouse_mickeys, install_keyboard, install_mouse, install_timer, key, keypressed, makecol, mouse_b, mouse_w, mouse_x, mouse_y, mouse_z, palette_color, poll_mouse, readkey, release_screen, screen, set_gfx_mode, set_mouse_sprite, set_mouse_sprite_focus, set_palette, show_mouse, textout_centre_ex, textout_ex, textprintf_centre_ex, textprintf_ex, textprintf_right_ex, vsync.
See also: END_OF_FUNCTION, END_OF_MAIN, LOCK_FUNCTION, LOCK_VARIABLE, SCREEN_W, allegro_error, allegro_init, allegro_message, clear_to_color, desktop_palette, font, install_int, install_int_ex, install_keyboard, install_timer, key, keypressed, makecol, readkey, rest, screen, set_gfx_mode, set_palette, textprintf_centre_ex.
See also: END_OF_FUNCTION, END_OF_MAIN, LOCK_FUNCTION, SCREEN_H, SCREEN_W, acquire_screen, allegro_error, allegro_init, allegro_message, blit, clear_keybuf, clear_to_color, desktop_palette, font, install_keyboard, install_timer, key, key_shifts, keyboard_lowlevel_callback, keypressed, makecol, readkey, rectfill, release_screen, rest, scancode_to_name, screen, set_gfx_mode, set_palette, textout_ex, textprintf_centre_ex, textprintf_ex, ureadkey, usprintf, ustrzncpy.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, calibrate_joystick, calibrate_joystick_name, circle, clear_bitmap, clear_keybuf, create_bitmap, default_palette, destroy_bitmap, drawing_mode, font, install_joystick, install_keyboard, joy, key, keypressed, num_joysticks, palette_color, poll_joystick, putpixel, readkey, screen, set_gfx_mode, set_palette, textout_centre_ex, textprintf_centre_ex, textprintf_ex.
See also: END_OF_MAIN, SAMPLE, SCREEN_H, SCREEN_W, adjust_sample, allegro_error, allegro_init, allegro_message, clear_to_color, desktop_palette, destroy_sample, font, install_keyboard, install_sound, install_timer, key, load_sample, makecol, play_sample, poll_keyboard, rest, screen, set_display_switch_mode, set_gfx_mode, set_palette, textprintf_centre_ex.
See also: END_OF_MAIN, MIDI, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, clear_to_color, desktop_palette, destroy_midi, font, get_filename, get_midi_length, install_keyboard, install_sound, install_timer, key, keypressed, load_midi, makecol, midi_pause, midi_pos, midi_resume, midi_time, play_midi, readkey, rectfill, rest, screen, set_display_switch_mode, set_gfx_mode, set_palette, text_height, text_length, textprintf_centre_ex.
See also: DATAFILE, DIALOG, END_OF_MAIN, MENU, active_menu, alert, allegro_error, allegro_init, allegro_message, d_bitmap_proc, d_box_proc, d_button_proc, d_check_proc, d_clear_proc, d_ctext_proc, d_edit_proc, d_icon_proc, d_keyboard_proc, d_list_proc, d_menu_proc, d_radio_proc, d_rtext_proc, d_shadow_box_proc, d_slider_proc, d_text_list_proc, d_text_proc, d_textbox_proc, d_yield_proc, do_dialog, gui_bg_color, gui_fg_color, gui_mg_color, install_keyboard, install_mouse, install_timer, key, load_datafile, makecol, position_dialog, replace_filename, screen, set_dialog_color, set_gfx_mode, set_palette, unload_datafile, ustrtok, ustrzcat, ustrzcpy, uszprintf.
See also: BITMAP, DATAFILE, DIALOG, END_OF_MAIN, FONT, allegro_error, allegro_init, allegro_message, blit, circle, circlefill, clear_to_color, create_bitmap, d_button_proc, d_check_proc, d_clear_proc, d_edit_proc, desktop_palette, destroy_bitmap, do_dialog, fixcos, fixed, fixmul, fixsin, fixtoi, font, install_keyboard, install_mouse, install_timer, itofix, key, line, load_datafile, makecol, object_message, replace_filename, screen, set_gfx_mode, set_palette, unload_datafile.
Note how the Allegro unicode string functions resemble the functions you can find in the standard C library, only these handle Unicode on all platforms.
See also: BITMAP, DATAFILE, END_OF_MAIN, FONT, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, clear_to_color, create_bitmap, destroy_bitmap, font, install_int_ex, install_keyboard, install_timer, keypressed, load_datafile, replace_filename, rest, screen, set_gfx_mode, set_uformat, set_window_title, text_height, text_length, textout_ex, uconvert_ascii, unload_datafile, ustrcat, ustrcpy, ustrsize, ustrsizez.
See also: BITMAP, END_OF_MAIN, PALETTE, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, destroy_bitmap, install_keyboard, load_bitmap, readkey, screen, set_gfx_mode, set_palette.
See also: BITMAP, END_OF_MAIN, PALETTE, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, destroy_bitmap, install_keyboard, keypressed, load_pcx, replace_filename, screen, set_gfx_mode, set_palette, stretch_blit, vsync.
See also: BITMAP, END_OF_MAIN, RGB, SCREEN_H, SCREEN_W, allegro_init, allegro_message, blit, clear_bitmap, destroy_bitmap, font, get_config_argv, get_config_int, get_config_string, install_keyboard, line, load_bitmap, makecol, pop_config_state, push_config_state, readkey, screen, set_color_depth, set_config_file, set_gfx_mode, set_palette, stretch_blit, textout_centre_ex, textprintf_centre_ex, ustrdup, ustricmp.
See also: DATAFILE, END_OF_MAIN, allegro_error, allegro_init, allegro_message, blit, font, install_keyboard, load_datafile, makecol, readkey, replace_filename, screen, set_color_conversion, set_gfx_mode, set_palette, textout_ex, unload_datafile.
Why is the animate() routine coded in that way? As you probably know, VIDEO RAM is much slower than "normal" RAM, so it's advisable to reduce VRAM blits to a minimum. Drawing sprite on the screen (meaning in VRAM) and then clearing a background for it is not very fast. This example uses a different method which is much faster, but require a bit more memory.
First the buffer is cleared (it's a normal BITMAP), then the sprite is drawn on it, and when the drawing is finished this buffer is copied directly to the screen. So the end result is that there is a single VRAM blit instead of blitting/clearing the background and drawing a sprite on it. It's a good method even when you have to restore the background. And of course, it completely removes any flickering effect.
When one uses a big (ie. 800x600 background) and draws something on it, it's wise to use a copy of background somewhere in memory and restore background using this "virtual background". When blitting from VRAM in SVGA modes, it's probably, that drawing routines have to switch banks on video card. I think, I don't have to remind how slow is it.
Note that on modern systems, the above isn't true anymore, and you usually get the best performance by caching all your animations in video ram and doing only VRAM->VRAM blits, so there is no more RAM->VRAM transfer at all anymore. And usually, such transfers can run in parallel on the graphics card's processor as well, costing virtually no main cpu time at all. See the exaccel example for an example of this.
See also: BITMAP, DATAFILE, END_OF_FUNCTION, END_OF_MAIN, LOCK_FUNCTION, LOCK_VARIABLE, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, circle, clear_bitmap, clear_keybuf, create_bitmap, destroy_bitmap, draw_sprite, draw_sprite_h_flip, draw_sprite_v_flip, draw_sprite_vh_flip, fixed, font, hline, install_int_ex, install_keyboard, install_sound, install_timer, itofix, key, keypressed, load_datafile, makecol, palette_color, pivot_sprite, pivot_sprite_v_flip, play_sample, rectfill, replace_filename, rest, screen, set_gfx_mode, set_palette, text_height, textout_centre_ex, unload_datafile, vsync.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, allegro_init, allegro_message, blit, clear_to_color, create_bitmap, destroy_bitmap, draw_trans_sprite, fixed, font, ftofix, install_keyboard, key, keypressed, load_bitmap, makeacol, makecol, readkey, rest, rotate_scaled_sprite, rotate_scaled_sprite_lit, rotate_scaled_sprite_trans, screen, set_alpha_blender, set_color_conversion, set_color_depth, set_gfx_mode, set_trans_blender, textout_centre_ex.
You may ask: how do you compile, append and exec your program?
Answer: like this...
1) Compile your program like normal. Use the magic filenames with '#' to load your data where needed.
2) Once you compressed your program, run "exedat foo.exe data.dat"
3) Finally run your program.
Note that appending data to the end of binaries may not be portable across all platforms supported by Allegro.
See also: DATAFILE, END_OF_MAIN, allegro_error, allegro_init, allegro_message, blit, font, install_keyboard, line, load_datafile, makecol, readkey, screen, set_color_conversion, set_gfx_mode, set_palette, textout_ex, unload_datafile.
The translucency effect is easy to do in all color depths. However, the lighting effect has to be performed in a different way depending on whether the screen is in 8bit mode or another color depth. This is because additive drawing mode uses a different set of routines for truecolor modes.
See also: BITMAP, COLOR_MAP, END_OF_MAIN, PALETTE, RGB, RGB_MAP, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, bitmap_color_depth, blit, circlefill, clear_bitmap, clear_keybuf, color_map, create_bitmap, create_bitmap_ex, create_light_table, create_rgb_table, create_trans_table, destroy_bitmap, draw_trans_sprite, drawing_mode, install_keyboard, install_mouse, install_timer, keypressed, load_bitmap, mouse_x, mouse_y, poll_mouse, rectfill, replace_filename, rest, rgb_map, screen, set_alpha_blender, set_gfx_mode, set_palette, set_trans_blender, set_write_alpha_blender, stretch_blit.
See also: BITMAP, END_OF_MAIN, allegro_error, allegro_init, allegro_message, blit, clear_bitmap, create_bitmap, destroy_bitmap, draw_sprite_ex, font, install_keyboard, install_timer, key, load_bitmap, makecol, replace_filename, rest, screen, set_color_depth, set_gfx_mode, set_trans_blender, stretch_blit, textout_ex.
See also: END_OF_MAIN, PALETTE, RGB, SCREEN_H, SCREEN_W, acquire_screen, allegro_init, clear_to_color, font, generate_332_palette, install_keyboard, key, makecol, readkey, release_screen, screen, set_color_depth, set_gfx_mode, set_palette, textout_centre_ex, textout_ex, textprintf_ex, vline.
See also: BITMAP, COLOR_MAP, END_OF_MAIN, PALETTE, RGB, RGB_MAP, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, circlefill, clear_keybuf, color_map, create_bitmap, create_color_table, create_rgb_table, destroy_bitmap, drawing_mode, font, generate_332_palette, install_keyboard, keypressed, makecol, rectfill, rest, rgb_map, screen, set_gfx_mode, set_palette, textout_centre_ex, vsync.
Additionally this example also shows how to "inherit" the behaviour of a GUI object and extend it, here used to create the sliders.
See also: BITMAP, DIALOG, END_OF_MAIN, PALETTE, RGB, RGB_MAP, allegro_error, allegro_init, allegro_message, clear_to_color, create_bitmap_ex, create_rgb_table, d_bitmap_proc, d_box_proc, d_slider_proc, d_text_proc, destroy_bitmap, do_dialog, font, generate_332_palette, get_color_depth, hsv_to_rgb, install_keyboard, install_mouse, install_timer, key, makecol, makecol32, makecol8, object_message, rgb_map, rgb_to_hsv, screen, set_color, set_color_depth, set_gfx_mode, set_palette, textout_ex, vline, vsync.
See also: BITMAP, COLOR_MAP, END_OF_MAIN, PALETTE, RGB, RGB_MAP, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, clear_bitmap, color_map, create_bitmap, create_light_table, create_rgb_table, destroy_bitmap, draw_gouraud_sprite, font, install_keyboard, install_mouse, keypressed, line, load_bitmap, mouse_x, mouse_y, palette_color, poll_mouse, replace_filename, rgb_map, screen, set_gfx_mode, set_palette, set_trans_blender, show_mouse, textout_ex.
See also: BITMAP, END_OF_MAIN, PALETTE, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, circle, clear_bitmap, clear_keybuf, create_bitmap, destroy_bitmap, draw_lit_sprite, draw_trans_sprite, fixcos, fixsin, fixtoi, font, install_keyboard, install_timer, itofix, keypressed, load_bitmap, makecol, replace_filename, retrace_count, screen, set_color_conversion, set_color_depth, set_gfx_mode, set_trans_blender, textprintf_ex, vsync.
See also: BITMAP, END_OF_MAIN, PALETTE, SCREEN_H, SCREEN_W, allegro_error, allegro_exit, allegro_init, allegro_message, blit, create_bitmap, destroy_bitmap, draw_trans_sprite, install_keyboard, keypressed, line, load_bitmap, readkey, rest, screen, set_color_conversion, set_color_depth, set_gfx_mode, set_palette, set_trans_blender, vsync.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, blit, clear_keybuf, create_bitmap, destroy_bitmap, draw_trans_sprite, drawing_mode, font, getb, getg, getpixel, getr, install_keyboard, install_mouse, install_timer, keypressed, load_bitmap, makecol, mouse_x, mouse_y, putpixel, rectfill, replace_filename, screen, set_alpha_blender, set_color_conversion, set_color_depth, set_gfx_mode, set_multiply_blender, set_write_alpha_blender, solid_mode, stretch_blit, textprintf_ex.
The basic approach is to select a 15 or 16 bit screen mode, but then draw onto 24 bit memory bitmaps. Since we only need the bottom 5 bits of each 8 bit color in order to store 15 bit data within a 24 bit location, we can fit a light level into the top 3 bits. The tricky bit is that these aren't actually 24 bit images at all: they are implemented as 8 bit memory bitmaps, and we just store the red level in one pixel, green in the next, and blue in the next, making the total image be three times wider than we really wanted. This allows us to use all the normal 256 color graphics routines for drawing onto our memory surfaces, most importantly the lookup table translucency, which can be used to combine the low 5 bits of color and the top 3 bits of light in a single drawing operation. Some trickery is needed to load 24 bit data into this fake 8 bit format, and of course it needs a custom routine to convert the resulting image while copying it across to the hardware screen.
This program chugs slightly on my p133, but not significantly worse than any double buffering in what amounts to a 1920x640, 256 color resolution. The light blending doesn't seem to slow it down too badly, so I think this technique would be quite usable on faster machines and in lower resolution hicolor modes. The biggest problem is that although you keep the full 15 bit color resolution, you only get 3 bits of light, ie. 8 light levels. You can do some nice colored light patches, but smooth gradients aren't going to work too well :-)
See also: BITMAP, COLOR_MAP, END_OF_MAIN, PALETTE, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, bitmap_color_depth, blit, bmp_unwrite_line, bmp_write_line, circlefill, clear_bitmap, clear_keybuf, color_map, create_bitmap_ex, destroy_bitmap, draw_trans_sprite, fixatan2, fixsqrt, fixtoi, getb_depth, getg_depth, getpixel, getr_depth, hsv_to_rgb, install_keyboard, install_mouse, install_timer, itofix, key, keypressed, line, load_bitmap, makecol, mouse_x, mouse_y, poll_mouse, replace_filename, retrace_count, screen, select_palette, set_color_conversion, set_color_depth, set_gfx_mode.
The example first shows a screen resolution selection dialog. Then, a number of bouncing 3d cubes are animated. Pressing a key modifies the rendering of the cubes, which can be wireframe, the more complex transparent perspective correct texture mapped version, and many other.
See also: BITMAP, COLOR_MAP, END_OF_MAIN, MATRIX, PALETTE, POLYTYPE_ATEX, POLYTYPE_ATEX_LIT, POLYTYPE_ATEX_MASK, POLYTYPE_ATEX_MASK_LIT, POLYTYPE_ATEX_MASK_TRANS, POLYTYPE_ATEX_TRANS, POLYTYPE_FLAT, POLYTYPE_GCOL, POLYTYPE_GRGB, POLYTYPE_PTEX, POLYTYPE_PTEX_LIT, POLYTYPE_PTEX_MASK, POLYTYPE_PTEX_MASK_LIT, POLYTYPE_PTEX_MASK_TRANS, POLYTYPE_PTEX_TRANS, RGB, RGB_MAP, SCREEN_H, SCREEN_W, V3D, allegro_error, allegro_exit, allegro_init, allegro_message, apply_matrix, bitmap_color_depth, bitmap_mask_color, blit, clear_bitmap, clear_to_color, color_map, create_bitmap, create_light_table, create_rgb_table, create_trans_table, desktop_palette, destroy_bitmap, fixed, fixtoi, font, get_transformation_matrix, gfx_mode_select_ex, install_keyboard, install_mouse, install_timer, itofix, key, keypressed, line, palette_color, persp_project, polygon_z_normal, quad3d, readkey, rect, retrace_count, rgb_map, screen, set_color_depth, set_gfx_mode, set_palette, set_projection_viewport, set_trans_blender, textout_ex, textprintf_ex, vsync.
See also: BITMAP, END_OF_MAIN, MATRIX_f, POLYTYPE_FLAT, SCREEN_H, SCREEN_W, V3D_f, allegro_error, allegro_init, allegro_message, apply_matrix_f, blit, clear_to_color, clip3d_f, create_bitmap, desktop_palette, destroy_bitmap, font, get_camera_matrix_f, get_vector_rotation_matrix_f, install_int_ex, install_keyboard, install_timer, key, key_shifts, makecol, persp_project_f, poll_keyboard, polygon, polygon3d_f, rect, screen, set_clip_rect, set_gfx_mode, set_palette, set_projection_viewport, textprintf_ex, vsync.
In this program, two cubes are rotated between random orientations. Notice that although they have the same beginning and ending orientations, they do not follow the same path between orientations.
One cube is being rotated by directly incrementing or decrementing the Euler angles from the starting point to the ending point. This is an intuitive notion, but it is incorrect because it does not cause the object to turn around a single unchanging axis of rotation. The axis of rotation wobbles resulting in the object spinning in strange ways. The object will eventually end up in the orientation that the user intended, but it gets there in a way that is unattractive. Imagine if this method was used to update the position of a camera in a game! Sometimes it would swing wildly and disorient the player.
The other cube is animated using quaternions. This results in a much more pleasing animation because the cube turns around a single axis of rotation.
See also: BITMAP, END_OF_MAIN, MATRIX_f, QUAT, acquire_bitmap, allegro_error, allegro_init, allegro_message, apply_matrix_f, blit, circle, clear_keybuf, clear_to_color, create_bitmap, desktop_palette, destroy_bitmap, font, get_camera_matrix_f, get_rotation_matrix, get_rotation_matrix_f, get_rotation_quat, install_keyboard, keypressed, line, matrix_mul_f, palette_color, persp_project_f, quat_interpolate, quat_to_matrix, readkey, release_bitmap, rest, screen, set_gfx_mode, set_palette, set_projection_viewport, textout_ex.
See also: BITMAP, END_OF_MAIN, MATRIX, PALETTE, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, apply_matrix, blit, clear_bitmap, create_bitmap, cross_product, destroy_bitmap, dot_product, fixed, fixmul, fixtof, fixtoi, font, get_rotation_matrix, get_transformation_matrix, get_translation_matrix, install_keyboard, install_timer, itofix, key, normalize_vector, palette_color, persp_project, poll_keyboard, putpixel, rectfill, screen, set_gfx_mode, set_palette, set_projection_viewport, textout_centre_ex, textprintf_centre_ex, triangle, vsync.
See also: BITMAP, END_OF_FUNCTION, END_OF_MAIN, LOCK_FUNCTION, LOCK_VARIABLE, MATRIX_f, PALETTE, POLYTYPE_GCOL, SCREEN_H, SCREEN_W, V3D_f, allegro_error, allegro_exit, allegro_init, allegro_message, apply_matrix_f, bitmap_color_depth, blit, clear_bitmap, clear_scene, clip3d_f, create_bitmap, create_scene, desktop_palette, destroy_bitmap, destroy_scene, font, get_rotation_matrix_f, get_translation_matrix_f, gfx_mode_select_ex, install_int, install_keyboard, install_mouse, install_timer, key, matrix_mul_f, palette_color, persp_project_f, polygon_z_normal_f, render_scene, scene_polygon3d_f, screen, set_color_depth, set_gfx_mode, set_palette, set_projection_viewport, textprintf_ex.
See also: BITMAP, END_OF_FUNCTION, END_OF_MAIN, LOCK_FUNCTION, LOCK_VARIABLE, MATRIX_f, PALETTE, POLYTYPE_GCOL, SCREEN_H, SCREEN_W, V3D_f, ZBUFFER, allegro_error, allegro_exit, allegro_init, allegro_message, apply_matrix_f, bitmap_color_depth, blit, clear_bitmap, clear_zbuffer, create_bitmap, create_zbuffer, desktop_palette, destroy_bitmap, destroy_zbuffer, font, get_transformation_matrix_f, gfx_mode_select_ex, install_int, install_keyboard, install_mouse, install_timer, keypressed, palette_color, persp_project_f, polygon_z_normal_f, quad3d_f, readkey, screen, set_color_depth, set_gfx_mode, set_palette, set_palette_range, set_projection_viewport, set_zbuffer, textprintf_ex, vsync.
See also: BITMAP, END_OF_MAIN, RGB, SCREEN_H, SCREEN_W, acquire_bitmap, allegro_init, allegro_message, clear_keybuf, create_sub_bitmap, desktop_palette, destroy_bitmap, install_keyboard, keypressed, rectfill, release_bitmap, rest, screen, scroll_screen, set_color, set_gfx_mode, set_palette, vline.
See also: BITMAP, END_OF_MAIN, SCREEN_H, SCREEN_W, acquire_bitmap, allegro_error, allegro_init, allegro_message, clear_bitmap, clear_keybuf, create_video_bitmap, desktop_palette, destroy_bitmap, enable_triple_buffer, fixcos, fixed, fixmul, fixsin, fixtoi, font, gfx_capabilities, install_keyboard, install_mouse, install_timer, itofix, keypressed, poll_scroll, release_bitmap, request_video_bitmap, screen, set_gfx_mode, set_palette, textout_ex, triangle, ustrzcpy.
The example starts setting a normal 256 color mode, and construct a special palette for it. But then comes the trick: you need to write to a set of two adjacent pixels to form a single 12 bit dot. Two eight bit pixels is the same as one 16 bit pixel, so after setting the video mode you need to hack the screen bitmap about, halving the width and changing it to use the 16 bit drawing code. Then, once you have packed a color into the correct format (using the makecol12() function below), any of the normal Allegro drawing functions can be used with this 12 bit display!
Things to note:
See also: BITMAP, END_OF_MAIN, MATRIX, PALETTE, RGB, allegro_error, allegro_init, allegro_message, apply_matrix, blit, circle, clear_bitmap, clear_keybuf, clear_to_color, create_bitmap, create_bitmap_ex, destroy_bitmap, ellipsefill, fade_out, fixcos, fixed, fixsin, fixtoi, font, get_rotation_matrix, getpixel, install_keyboard, itofix, keypressed, line, makecol, masked_blit, putpixel, rest, screen, set_clip_rect, set_color, set_gfx_mode, set_palette, text_height, text_length, textout_ex, textprintf_ex.
See also: BITMAP, END_OF_MAIN, PALETTE, SCREEN_H, SCREEN_W, acquire_bitmap, allegro_error, allegro_init, allegro_message, blit, clear_bitmap, create_video_bitmap, destroy_bitmap, font, gfx_capabilities, install_keyboard, install_timer, keypressed, load_bitmap, readkey, release_bitmap, replace_filename, screen, set_gfx_mode, set_palette, show_video_bitmap, textout_ex, textprintf_ex.
The technique is to connect the series of guide points p1..p(n) with spline curves from p1-p2, p2-p3, etc. Each spline must pass though both of its guide points, so they must be used as the first and fourth of the spline control points. The fun bit is coming up with sensible values for the second and third spline control points, such that the spline segments will have equal gradients where they meet. I came up with the following solution:
For each guide point p(n), calculate the desired tangent to the curve at that point. I took this to be the vector p(n-1) -> p(n+1), which can easily be calculated with the inverse tangent function, and gives decent looking results. One implication of this is that two dummy guide points are needed at each end of the curve, which are used in the tangent calculations but not connected to the set of splines.
Having got these tangents, it becomes fairly easy to calculate the spline control points. For a spline between guide points p(a) and p(b), the second control point should lie along the positive tangent from p(a), and the third control point should lie along the negative tangent from p(b). How far they are placed along these tangents controls the shape of the curve: I found that applying a 'curviness' scaling factor to the distance between p(a) and p(b) works well.
One thing to note about splines is that the generated points are not all equidistant. Instead they tend to bunch up nearer to the ends of the spline, which means you will need to apply some fudges to get an object to move at a constant speed. On the other hand, in situations where the curve has a noticeable change of direction at each guide point, the effect can be quite nice because it makes the object slow down for the curve.
See also: END_OF_MAIN, SCREEN_W, acquire_screen, alert, allegro_error, allegro_init, allegro_message, calc_spline, circlefill, clear_keybuf, clear_to_color, desktop_palette, fixatan2, fixcos, fixed, fixmul, fixsin, fixsqrt, fixtof, fixtoi, font, ftofix, install_keyboard, install_mouse, install_timer, itofix, key, keypressed, line, makecol, mouse_b, mouse_x, mouse_y, palette_color, poll_mouse, readkey, release_screen, screen, set_gfx_mode, set_palette, show_mouse, spline, textout_centre_ex, textprintf_centre_ex, textprintf_ex, vsync, xor_mode.
See also: END_OF_MAIN, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, clear_to_color, enable_hardware_cursor, font, gfx_capabilities, install_keyboard, install_mouse, install_timer, makecol, readkey, screen, select_mouse_cursor, set_gfx_mode, show_mouse, text_height, textprintf_centre_ex.
See also: BITMAP, END_OF_FUNCTION, END_OF_MAIN, LOCK_FUNCTION, LOCK_VARIABLE, PALETTE, SCREEN_H, SCREEN_W, acquire_bitmap, allegro_error, allegro_init, allegro_message, bitmap_color_depth, blit, clear_bitmap, create_bitmap, create_system_bitmap, create_video_bitmap, desktop_palette, destroy_bitmap, enable_triple_buffer, fixcos, fixed, fixmul, fixsin, fixtoi, font, ftofix, generate_332_palette, gfx_capabilities, gfx_mode_select_ex, install_int_ex, install_keyboard, install_mouse, install_timer, keypressed, line, makecol, poll_scroll, release_bitmap, request_video_bitmap, screen, set_color_depth, set_gfx_mode, set_palette, show_video_bitmap, textout_ex, textprintf_ex, triangle, vsync, xor_mode.
Yes, I know the fractal drawing is very slow: that's the point! This is so you can easily check whether it goes on working in the background after you switch away from the app.
Depending on the type of selected switching mode, you will see whether the contents of the screen are preserved or not.
See also: BITMAP, END_OF_FUNCTION, END_OF_MAIN, LOCK_FUNCTION, LOCK_VARIABLE, PALETTE, SCREEN_H, SCREEN_W, acquire_bitmap, acquire_screen, allegro_error, allegro_exit, allegro_init, allegro_message, bitmap_color_depth, blit, clear_to_color, create_sub_bitmap, desktop_palette, destroy_bitmap, font, get_display_switch_mode, gfx_mode_select_ex, install_int, install_keyboard, install_mouse, install_timer, keypressed, makecol, palette_color, putpixel, readkey, rectfill, release_bitmap, release_screen, screen, set_color_depth, set_display_switch_callback, set_display_switch_mode, set_gfx_mode, set_palette, textout_centre_ex, textprintf_centre_ex.
See also: AUDIOSTREAM, END_OF_MAIN, SCREEN_H, SCREEN_W, allegro_error, allegro_init, allegro_message, clear_to_color, desktop_palette, font, free_audio_stream_buffer, get_audio_stream_buffer, install_keyboard, install_sound, install_timer, keypressed, makecol, play_audio_stream, readkey, screen, set_display_switch_mode, set_gfx_mode, set_palette, stop_audio_stream, textprintf_centre_ex, voice_start, voice_stop.
The first test uses the standard packfile functions to transfer a bitmap file into a block of memory, then reads the bitmap out of the block of memory, using a custom packfile vtable.
The second test reads in a bitmap with another custom packfile vtable, which uses libc's file stream functions.
The third test demonstrates seeking with a custom vtable.
The fourth test reads two bitmaps, and dumps them back into a single file, using a custom vtable again.
See also: ASSERT, BITMAP, END_OF_MAIN, PACKFILE, PACKFILE_VTABLE, SCREEN_H, SCREEN_W, alert, allegro_error, allegro_init, allegro_message, blit, clear_bitmap, destroy_bitmap, file_size_ex, font, install_keyboard, key, load_bmp_pf, load_pcx, load_pcx_pf, load_tga_pf, pack_fclose, pack_fopen, pack_fopen_vtable, pack_fread, pack_fseek, readkey, save_bmp_pf, save_tga_pf, screen, set_color_depth, set_gfx_mode, text_height, textprintf_centre_ex, textprintf_ex.