mutter/examples/cogl-point-sprites.c

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#include <cogl/cogl.h>
#include <glib.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#define N_FIREWORKS 32
/* Units per second per second */
#define GRAVITY -1.5f
#define N_SPARKS (N_FIREWORKS * 32) /* Must be a power of two */
#define TIME_PER_SPARK 0.01f /* in seconds */
#define TEXTURE_SIZE 32
typedef struct
{
uint8_t red, green, blue, alpha;
} Color;
typedef struct
{
float size;
float x, y;
float start_x, start_y;
Color color;
/* Velocities are in units per second */
float initial_x_velocity;
float initial_y_velocity;
GTimer *timer;
} Firework;
typedef struct
{
float x, y;
Color color;
Color base_color;
} Spark;
typedef struct
{
Firework fireworks[N_FIREWORKS];
int next_spark_num;
Spark sparks[N_SPARKS];
GTimer *last_spark_time;
CoglContext *context;
CoglFramebuffer *fb;
CoglPipeline *pipeline;
CoglPrimitive *primitive;
CoglAttributeBuffer *attribute_buffer;
} Data;
static CoglTexture *
generate_round_texture (CoglContext *context)
{
uint8_t *p, *data;
int x, y;
CoglTexture2D *tex;
p = data = g_malloc (TEXTURE_SIZE * TEXTURE_SIZE * 4);
/* Generate a white circle which gets transparent towards the edges */
for (y = 0; y < TEXTURE_SIZE; y++)
for (x = 0; x < TEXTURE_SIZE; x++)
{
int dx = x - TEXTURE_SIZE / 2;
int dy = y - TEXTURE_SIZE / 2;
float value = sqrtf (dx * dx + dy * dy) * 255.0 / (TEXTURE_SIZE / 2);
if (value > 255.0f)
value = 255.0f;
value = 255.0f - value;
*(p++) = value;
*(p++) = value;
*(p++) = value;
*(p++) = value;
}
tex = cogl_texture_2d_new_from_data (context,
TEXTURE_SIZE, TEXTURE_SIZE,
COGL_PIXEL_FORMAT_RGBA_8888_PRE,
TEXTURE_SIZE * 4,
data,
NULL /* error */);
g_free (data);
return tex;
}
static void
paint (Data *data)
{
int i;
float diff_time;
/* Update all of the firework's positions */
for (i = 0; i < N_FIREWORKS; i++)
{
Firework *firework = data->fireworks + i;
if ((fabsf (firework->x - firework->start_x) > 2.0f) ||
firework->y < -1.0f)
{
firework->size = g_random_double_range (0.001f, 0.1f);
firework->start_x = 1.0f + firework->size;
firework->start_y = -1.0f;
firework->initial_x_velocity = g_random_double_range (-0.1f, -2.0f);
firework->initial_y_velocity = g_random_double_range (0.1f, 4.0f);
g_timer_reset (firework->timer);
/* Pick a random color out of six */
if (g_random_boolean ())
{
memset (&firework->color, 0, sizeof (Color));
((uint8_t *) &firework->color)[g_random_int_range (0, 3)] = 255;
}
else
{
memset (&firework->color, 255, sizeof (Color));
((uint8_t *) &firework->color)[g_random_int_range (0, 3)] = 0;
}
firework->color.alpha = 255;
/* Fire some of the fireworks from the other side */
if (g_random_boolean ())
{
firework->start_x = -firework->start_x;
firework->initial_x_velocity = -firework->initial_x_velocity;
}
}
diff_time = g_timer_elapsed (firework->timer, NULL);
firework->x = (firework->start_x +
firework->initial_x_velocity * diff_time);
firework->y = ((firework->initial_y_velocity * diff_time +
0.5f * GRAVITY * diff_time * diff_time) +
firework->start_y);
}
diff_time = g_timer_elapsed (data->last_spark_time, NULL);
if (diff_time < 0.0f || diff_time >= TIME_PER_SPARK)
{
/* Add a new spark for each firework, overwriting the oldest ones */
for (i = 0; i < N_FIREWORKS; i++)
{
Spark *spark = data->sparks + data->next_spark_num;
Firework *firework = data->fireworks + i;
spark->x = (firework->x +
g_random_double_range (-firework->size / 2.0f,
firework->size / 2.0f));
spark->y = (firework->y +
g_random_double_range (-firework->size / 2.0f,
firework->size / 2.0f));
spark->base_color = firework->color;
data->next_spark_num = (data->next_spark_num + 1) & (N_SPARKS - 1);
}
/* Update the colour of each spark */
for (i = 0; i < N_SPARKS; i++)
{
float color_value;
/* First spark is the oldest */
Spark *spark = data->sparks + ((data->next_spark_num + i)
& (N_SPARKS - 1));
color_value = i / (N_SPARKS - 1.0f);
spark->color.red = spark->base_color.red * color_value;
spark->color.green = spark->base_color.green * color_value;
spark->color.blue = spark->base_color.blue * color_value;
spark->color.alpha = 255.0f * color_value;
}
g_timer_reset (data->last_spark_time);
}
cogl_buffer_set_data (data->attribute_buffer,
0, /* offset */
data->sparks,
sizeof (data->sparks));
cogl_framebuffer_clear4f (data->fb, COGL_BUFFER_BIT_COLOR, 0, 0, 0, 1);
cogl_primitive_draw (data->primitive,
data->fb,
data->pipeline);
cogl_onscreen_swap_buffers (data->fb);
}
static void
create_primitive (Data *data)
{
CoglAttribute *attributes[2];
int i;
data->attribute_buffer =
cogl_attribute_buffer_new_with_size (data->context,
sizeof (data->sparks));
cogl_buffer_set_update_hint (data->attribute_buffer,
COGL_BUFFER_UPDATE_HINT_DYNAMIC);
attributes[0] = cogl_attribute_new (data->attribute_buffer,
"cogl_position_in",
sizeof (Spark),
G_STRUCT_OFFSET (Spark, x),
2, /* n_components */
COGL_ATTRIBUTE_TYPE_FLOAT);
attributes[1] = cogl_attribute_new (data->attribute_buffer,
"cogl_color_in",
sizeof (Spark),
G_STRUCT_OFFSET (Spark, color),
4, /* n_components */
COGL_ATTRIBUTE_TYPE_UNSIGNED_BYTE);
data->primitive =
cogl_primitive_new_with_attributes (COGL_VERTICES_MODE_POINTS,
N_SPARKS,
attributes,
G_N_ELEMENTS (attributes));
for (i = 0; i < G_N_ELEMENTS (attributes); i++)
cogl_object_unref (attributes[i]);
}
static void
frame_event_cb (CoglOnscreen *onscreen,
CoglFrameEvent event,
CoglFrameInfo *info,
void *user_data)
{
Data *data = user_data;
if (event == COGL_FRAME_EVENT_SYNC)
paint (data);
}
int
main (int argc, char *argv[])
{
CoglTexture *tex;
CoglOnscreen *onscreen;
GSource *cogl_source;
GMainLoop *loop;
Data data;
int i;
data.context = cogl_context_new (NULL, NULL);
create_primitive (&data);
data.pipeline = cogl_pipeline_new (data.context);
data.last_spark_time = g_timer_new ();
data.next_spark_num = 0;
cogl_pipeline_set_point_size (data.pipeline, TEXTURE_SIZE);
tex = generate_round_texture (data.context);
cogl_pipeline_set_layer_texture (data.pipeline, 0, tex);
cogl_object_unref (tex);
cogl_pipeline_set_layer_point_sprite_coords_enabled (data.pipeline,
0, /* layer */
TRUE,
NULL /* error */);
for (i = 0; i < N_FIREWORKS; i++)
{
data.fireworks[i].x = -FLT_MAX;
data.fireworks[i].y = FLT_MAX;
data.fireworks[i].size = 0.0f;
data.fireworks[i].timer = g_timer_new ();
}
for (i = 0; i < N_SPARKS; i++)
{
data.sparks[i].x = 2.0f;
data.sparks[i].y = 2.0f;
}
onscreen = cogl_onscreen_new (data.context, 800, 600);
cogl_onscreen_show (onscreen);
data.fb = onscreen;
cogl_source = cogl_glib_source_new (data.context, G_PRIORITY_DEFAULT);
g_source_attach (cogl_source, NULL);
cogl_onscreen_add_frame_callback (onscreen,
frame_event_cb,
&data,
NULL /* destroy notify */);
loop = g_main_loop_new (NULL, TRUE);
paint (&data);
g_main_loop_run (loop);
g_main_loop_unref (loop);
g_source_destroy (cogl_source);
cogl_object_unref (data.pipeline);
cogl_object_unref (data.attribute_buffer);
cogl_object_unref (data.primitive);
cogl_object_unref (onscreen);
cogl_object_unref (data.context);
g_timer_destroy (data.last_spark_time);
for (i = 0; i < N_FIREWORKS; i++)
g_timer_destroy (data.fireworks[i].timer);
return 0;
}