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