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
|
#include <cogl/cogl.h>
#include <stdio.h>
#include <SDL.h>
#include <emscripten.h>
#include "emscripten-example-js.h"
/* This short example is just to demonstrate using Cogl with
* Emscripten using SDL to receive input events */
typedef struct Data
{
CoglPrimitive *triangle;
CoglPipeline *pipeline;
float center_x, center_y;
CoglFramebuffer *fb;
CoglBool redraw_queued;
CoglBool ready_to_draw;
} Data;
static Data data;
static CoglContext *ctx;
static void
redraw (Data *data)
{
CoglFramebuffer *fb = data->fb;
cogl_framebuffer_clear4f (fb, COGL_BUFFER_BIT_COLOR, 0, 0, 0, 1);
cogl_framebuffer_push_matrix (fb);
cogl_framebuffer_translate (fb, data->center_x, -data->center_y, 0.0f);
cogl_primitive_draw (data->triangle, fb, data->pipeline);
cogl_framebuffer_pop_matrix (fb);
cogl_onscreen_swap_buffers (COGL_ONSCREEN (fb));
}
static void
handle_event (Data *data, SDL_Event *event)
{
switch (event->type)
{
case SDL_MOUSEMOTION:
{
int width =
cogl_framebuffer_get_width (COGL_FRAMEBUFFER (data->fb));
int height =
cogl_framebuffer_get_height (COGL_FRAMEBUFFER (data->fb));
data->center_x = event->motion.x * 2.0f / width - 1.0f;
data->center_y = event->motion.y * 2.0f / height - 1.0f;
data->redraw_queued = TRUE;
}
break;
}
}
static void
frame_cb (CoglOnscreen *onscreen,
CoglFrameEvent event,
CoglFrameInfo *info,
void *user_data)
{
Data *data = user_data;
if (event == COGL_FRAME_EVENT_SYNC)
data->ready_to_draw = TRUE;
}
static void
mainloop (void)
{
SDL_Event event;
while (SDL_PollEvent (&event))
{
handle_event (&data, &event);
cogl_sdl_handle_event (ctx, &event);
}
if (data.redraw_queued && data.ready_to_draw)
{
data.redraw_queued = FALSE;
data.ready_to_draw = FALSE;
redraw (&data);
}
/* NB: The mainloop will be automatically resumed if user input is received */
if (!data.redraw_queued)
emscripten_pause_main_loop ();
cogl_sdl_idle (ctx);
}
int
main (int argc, char **argv)
{
CoglOnscreen *onscreen;
CoglError *error = NULL;
CoglVertexP2C4 triangle_vertices[] = {
{0, 0.7, 0xff, 0x00, 0x00, 0xff},
{-0.7, -0.7, 0x00, 0xff, 0x00, 0xff},
{0.7, -0.7, 0x00, 0x00, 0xff, 0xff}
};
ctx = cogl_sdl_context_new (SDL_USEREVENT, &error);
if (!ctx)
{
fprintf (stderr, "Failed to create context: %s\n", error->message);
return 1;
}
onscreen = cogl_onscreen_new (ctx, 800, 600);
data.fb = COGL_FRAMEBUFFER (onscreen);
cogl_onscreen_add_frame_callback (onscreen,
frame_cb,
&data,
NULL /* destroy callback */);
data.center_x = 0.0f;
data.center_y = 0.0f;
cogl_onscreen_show (onscreen);
data.triangle = cogl_primitive_new_p2c4 (ctx, COGL_VERTICES_MODE_TRIANGLES,
3, triangle_vertices);
data.pipeline = cogl_pipeline_new (ctx);
data.redraw_queued = TRUE;
data.ready_to_draw = TRUE;
/* The emscripten mainloop isn't event driven, it's periodic and so
* we aim to pause the emscripten mainlooop whenever we don't have a
* redraw queued. What we do instead is hook into the real browser
* mainloop using this javascript binding api to add an input event
* listener that will resume the emscripten mainloop whenever input
* is received.
*/
example_js_add_input_listener ();
emscripten_set_main_loop (mainloop, -1, TRUE);
cogl_object_unref (ctx);
return 0;
}
|
