1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
/*
* This example exercises line drawing, and single buffer mode.
*/
#include <math.h>
#include "allegro5/allegro.h"
#include <allegro5/allegro_primitives.h>
#include "common.c"
/* XXX the software line drawer currently doesn't perform clipping properly */
const int W = 640;
const int H = 480;
ALLEGRO_DISPLAY *display;
ALLEGRO_EVENT_QUEUE *queue;
ALLEGRO_COLOR black;
ALLEGRO_COLOR white;
ALLEGRO_COLOR background;
ALLEGRO_BITMAP *dbuf;
int last_x = -1;
int last_y = -1;
static void fade(void)
{
al_set_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_INVERSE_ALPHA);
al_draw_filled_rectangle(0, 0, W, H, al_map_rgba_f(0.5, 0.5, 0.6, 0.2));
}
static void red_dot(int x, int y)
{
al_draw_filled_rectangle(x - 2, y - 2, x + 2, y + 2, al_map_rgb_f(1, 0, 0));
}
static void draw_clip_rect(void)
{
al_draw_rectangle(100.5, 100.5, W - 100.5, H - 100.5, black, 0);
}
static void my_set_clip_rect(void)
{
al_set_clipping_rectangle(100, 100, W - 200, H - 200);
}
static void reset_clip_rect(void)
{
al_set_clipping_rectangle(0, 0, W, H);
}
static void flip(void)
{
al_set_target_backbuffer(display);
al_set_blender(ALLEGRO_ADD, ALLEGRO_ONE, ALLEGRO_ZERO);
al_draw_bitmap(dbuf, 0.0, 0.0, 0);
al_flip_display();
}
static void plonk(const int x, const int y, bool blend)
{
al_set_target_bitmap(dbuf);
fade();
al_set_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_ZERO);
draw_clip_rect();
red_dot(x, y);
if (last_x == -1 && last_y == -1) {
last_x = x;
last_y = y;
}
else {
my_set_clip_rect();
if (blend) {
al_set_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_INVERSE_ALPHA);
}
al_draw_line(last_x, last_y, x, y, white, 0);
last_x = last_y = -1;
reset_clip_rect();
}
flip();
}
static void splat(const int x, const int y, bool blend)
{
double theta;
al_set_target_bitmap(dbuf);
fade();
al_set_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_ZERO);
draw_clip_rect();
red_dot(x, y);
my_set_clip_rect();
if (blend) {
al_set_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_INVERSE_ALPHA);
}
for (theta = 0.0; theta < 2.0 * ALLEGRO_PI; theta += ALLEGRO_PI/16.0) {
al_draw_line(x, y, x + 40.0 * cos(theta), y + 40.0 * sin(theta), white, 0);
}
reset_clip_rect();
flip();
}
int main(int argc, char **argv)
{
ALLEGRO_EVENT event;
ALLEGRO_KEYBOARD_STATE kst;
bool blend;
if (!al_init()) {
abort_example("Could not init Allegro.\n");
}
al_init_primitives_addon();
al_install_keyboard();
al_install_mouse();
display = al_create_display(W, H);
if (!display) {
abort_example("Error creating display\n");
}
black = al_map_rgb_f(0.0, 0.0, 0.0);
white = al_map_rgb_f(1.0, 1.0, 1.0);
background = al_map_rgb_f(0.5, 0.5, 0.6);
if (argc > 1 && 0 == strcmp(argv[1], "--memory-bitmap")) {
al_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP);
}
dbuf = al_create_bitmap(W, H);
if (!dbuf) {
abort_example("Error creating double buffer\n");
}
al_set_target_bitmap(dbuf);
al_clear_to_color(background);
draw_clip_rect();
flip();
queue = al_create_event_queue();
al_register_event_source(queue, al_get_keyboard_event_source());
al_register_event_source(queue, al_get_mouse_event_source());
while (true) {
al_wait_for_event(queue, &event);
if (event.type == ALLEGRO_EVENT_MOUSE_BUTTON_DOWN) {
al_get_keyboard_state(&kst);
blend = al_key_down(&kst, ALLEGRO_KEY_LSHIFT) ||
al_key_down(&kst, ALLEGRO_KEY_RSHIFT);
if (event.mouse.button == 1) {
plonk(event.mouse.x, event.mouse.y, blend);
} else {
splat(event.mouse.x, event.mouse.y, blend);
}
}
else if (event.type == ALLEGRO_EVENT_DISPLAY_SWITCH_OUT) {
last_x = last_y = -1;
}
else if (event.type == ALLEGRO_EVENT_KEY_DOWN &&
event.keyboard.keycode == ALLEGRO_KEY_ESCAPE)
{
break;
}
}
al_destroy_event_queue(queue);
al_destroy_bitmap(dbuf);
return 0;
}
/* vim: set sts=3 sw=3 et: */
|
