mutter/examples/cogl-hello.c
Neil Roberts 08b0d2d63e examples: Fix the first colour in the triangle_vertices
The first vertex in the triangle vertices used in the cogl-hello
example (which were copied into a few other examples) for some reason
has a semi-transparent alpha component. However the colour needs to be
pre-multiplied and the red component was still 0xff so the colour is
effectively invalid and the transparency isn't shown. This patch just
sets the alpha component to 0xff to make it less confusing.

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

(cherry picked from commit 461879986ec012556b4e680b73e36d440927faaa)
2013-04-22 13:01:45 +01:00

81 lines
2.1 KiB
C

#include <cogl/cogl.h>
#include <glib.h>
#include <stdio.h>
typedef struct _Data
{
CoglContext *ctx;
CoglFramebuffer *fb;
CoglPrimitive *triangle;
CoglPipeline *pipeline;
} Data;
static CoglBool
paint_cb (void *user_data)
{
Data *data = user_data;
cogl_framebuffer_clear4f (data->fb, COGL_BUFFER_BIT_COLOR, 0, 0, 0, 1);
cogl_framebuffer_draw_primitive (data->fb, data->pipeline, data->triangle);
cogl_onscreen_swap_buffers (COGL_ONSCREEN (data->fb));
return FALSE; /* remove the callback */
}
static void
frame_event_cb (CoglOnscreen *onscreen,
CoglFrameEvent event,
CoglFrameInfo *info,
void *user_data)
{
if (event == COGL_FRAME_EVENT_SYNC)
paint_cb (user_data);
}
int
main (int argc, char **argv)
{
Data data;
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}
};
GSource *cogl_source;
GMainLoop *loop;
data.ctx = cogl_context_new (NULL, &error);
if (!data.ctx) {
fprintf (stderr, "Failed to create context: %s\n", error->message);
return 1;
}
onscreen = cogl_onscreen_new (data.ctx, 640, 480);
cogl_onscreen_show (onscreen);
data.fb = COGL_FRAMEBUFFER (onscreen);
cogl_onscreen_set_resizable (onscreen, TRUE);
data.triangle = cogl_primitive_new_p2c4 (data.ctx,
COGL_VERTICES_MODE_TRIANGLES,
3, triangle_vertices);
data.pipeline = cogl_pipeline_new (data.ctx);
cogl_source = cogl_glib_source_new (data.ctx, G_PRIORITY_DEFAULT);
g_source_attach (cogl_source, NULL);
cogl_onscreen_add_frame_callback (COGL_ONSCREEN (data.fb),
frame_event_cb,
&data,
NULL); /* destroy notify */
g_idle_add (paint_cb, &data);
loop = g_main_loop_new (NULL, TRUE);
g_main_loop_run (loop);
return 0;
}