kc3-lang/kc3/libc3/window/sdl2/demo/lightspeed.c

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• Hash : 753ba038
  Author : Thomas de Grivel
  Date : 2023-12-06T09:39:47
  

  minor tweaks

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• libc3/window/sdl2/demo/lightspeed.c

• /* c3
   * Copyright 2022,2023 kmx.io <contact@kmx.io>
   *
   * Permission is hereby granted to use this software granted the above
   * copyright notice and this permission paragraph are included in all
   * copies and substantial portions of this software.
   *
   * THIS SOFTWARE IS PROVIDED "AS-IS" WITHOUT ANY GUARANTEE OF
   * PURPOSE AND PERFORMANCE. IN NO EVENT WHATSOEVER SHALL THE
   * AUTHOR BE CONSIDERED LIABLE FOR THE USE AND PERFORMANCE OF
   * THIS SOFTWARE.
   */
  #include <libc3/c3.h>
  #include "lightspeed.h"
  
  #define LIGHTSPEED_STAR_MAX (1024 * 1024)
  #define LIGHTSPEED_STAR_PROBABILITY 0.005
  
  static void star_init (s_tag *star)
  {
    f64 x;
    f64 y;
    f64_random(&x);
    f64_random(&y);
    if (star->type != TAG_MAP || star->data.map.count != 3) {
      tag_map(star, 3);
      tag_init_sym(star->data.map.keys + 0, sym_1("speed"));
      tag_init_sym(star->data.map.keys + 1, sym_1("x"));
      tag_init_sym(star->data.map.keys + 2, sym_1("y"));
    }
    tag_init_f64(star->data.map.values + 0, 0.0);
    tag_init_f64(star->data.map.values + 1, 2.0 * x - 1.0);
    tag_init_f64(star->data.map.values + 2, 2.0 * y - 1.0);
  }
  
  static void star_render (s_tag *star, s_sequence *seq)
  {
    f64 q;
    f64 *speed;
    f64 *x;
    f64 *y;
    if (star->type != TAG_MAP || star->data.map.count < 3)
      star_init(star);
    speed = &star->data.map.values[0].data.f64;
    x = &star->data.map.values[1].data.f64;
    y = &star->data.map.values[2].data.f64;
    glVertex2d(*x, *y);
    q = (1 + *speed / 20);
    glVertex2d(*x * q, *y * q);
    q = (1 + *speed / 100);
    *x = *x * q;
    *y = *y * q;
    *speed += seq->dt;
    if (*x < -1.0 || *x > 1.0 || *y < -1.0 || *y > 1.0)
      star_init(star);
  }
  
  bool lightspeed_load (s_sequence *seq, s_window_sdl2 *window)
  {
    uw i;
    uw star_count;
    (void) window;
    tag_tuple(&seq->tag, LIGHTSPEED_STAR_MAX);
    star_count = window->w * window->h * LIGHTSPEED_STAR_PROBABILITY;
    if (star_count > LIGHTSPEED_STAR_MAX)
      star_count = LIGHTSPEED_STAR_MAX;
    i = 0;
    while (i < star_count) {
      star_init(seq->tag.data.tuple.tag + i);
      i++;
    }
    return true;
  }
  
  bool lightspeed_render (s_sequence *seq, s_window_sdl2 *window,
                          void *context)
  {
    uw i;
    uw star_count;
    (void) window;
    (void) context;
    glDisable(GL_TEXTURE_2D);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    //glScale2d(window->w / 2.0, window->h / 2.0);
    //glTranslatef(1.0f, 1.0f, 0.0f);
    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    glLineWidth(2);
    glColor4f(1, 1, 1, 0.7f);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_LINE_SMOOTH);
    glBegin(GL_LINES);
    star_count = window->w * window->h * LIGHTSPEED_STAR_PROBABILITY;
    if (star_count > LIGHTSPEED_STAR_MAX)
      star_count = LIGHTSPEED_STAR_MAX;
    i = 0;
    while (i < star_count) {
      star_render(seq->tag.data.tuple.tag + i, seq);
      i++;
    }
    glEnd();
    return true;
  }
  

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