mutter/examples/cogl-sdl-hello.c
Neil Roberts 4efd82a3b6 Convert the two SDL examples to use the frame callback
The two SDL examples now throttle their rendering to the
COGL_FRAME_EVENT_SYNC event. Previously the examples would redraw
whenever a mouse motion event is received but now they additionally
wait for the sync event which means that if another mouse event comes
immediately after rendering the last frame it theoretically could
avoid blocking waiting for the last frame to complete. In practice
however the SDL winsys doesn't support swap events so it will get the
sync event immediately anyway, but it's nice to have the code as an
example and a test.

This patch also changes the mainloop a bit to do the equivalent steps
without the outer main loop which I think makes it a bit easier to
follow.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 97cdd832dded2ebfaa42ee4bc43319cb8648d01b)
2013-01-31 16:56:08 +00:00

146 lines
3.3 KiB
C

#include <cogl/cogl.h>
#include <stdio.h>
#include <SDL.h>
/* This short example is just to demonstrate mixing SDL with Cogl as a
simple way to get portable support for events */
typedef struct Data
{
CoglPrimitive *triangle;
CoglPipeline *pipeline;
float center_x, center_y;
CoglFramebuffer *fb;
CoglBool quit;
CoglBool redraw_queued;
CoglBool ready_to_draw;
} Data;
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_framebuffer_draw_primitive (fb, data->pipeline, data->triangle);
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_VIDEOEXPOSE:
data->redraw_queued = TRUE;
break;
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;
case SDL_QUIT:
data->quit = 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;
}
int
main (int argc, char **argv)
{
CoglContext *ctx;
CoglOnscreen *onscreen;
CoglError *error = NULL;
CoglVertexP2C4 triangle_vertices[] = {
{0, 0.7, 0xff, 0x00, 0x00, 0x80},
{-0.7, -0.7, 0x00, 0xff, 0x00, 0xff},
{0.7, -0.7, 0x00, 0x00, 0xff, 0xff}
};
Data data;
SDL_Event event;
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;
data.quit = FALSE;
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;
while (!data.quit)
{
if (!SDL_PollEvent (&event))
{
if (data.redraw_queued && data.ready_to_draw)
{
redraw (&data);
data.redraw_queued = FALSE;
data.ready_to_draw = FALSE;
continue;
}
cogl_sdl_idle (ctx);
if (!SDL_WaitEvent (&event))
{
fprintf (stderr, "Error waiting for SDL events");
return 1;
}
}
handle_event (&data, &event);
cogl_sdl_handle_event (ctx, &event);
}
cogl_object_unref (ctx);
return 0;
}