kc3-lang/kc3/gl/gl_sphere.c

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• Hash : a6af069c
  Author : Thomas de Grivel
  Date : 2025-09-30T13:11:16
  

  moved GL files to their own directory to share between EGL and SDL2
  

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• gl/gl_sphere.c

• /* kc3
   * Copyright from 2022 to 2025 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 <math.h>
  #include <libkc3/kc3.h>
  #include "gl_object.h"
  #include "gl_sphere.h"
  
  void gl_sphere_clean (s_gl_sphere *sphere)
  {
    assert(sphere);
    gl_object_clean(&sphere->object);
  }
  
  void gl_sphere_delete (s_gl_sphere *sphere)
  {
    assert(sphere);
    gl_sphere_clean(sphere);
    free(sphere);
  }
  
  s_gl_sphere * gl_sphere_init (s_gl_sphere *sphere, u32 seg_u, u32 seg_v)
  {
    f64 angle_i;
    f64 angle_j;
    u32 i;
    u32 j;
    s_gl_vertex *vertex;
    f64 r;
    s_gl_sphere tmp = {0};
    s_gl_triangle *triangle;
    f64 z;
    assert(sphere);
    if (seg_u < 3)
      seg_u = 3;
    if (seg_v < 1)
      seg_v = 1;
    tmp.segments_u = seg_u;
    tmp.segments_v = seg_v;
    if (! gl_object_init(&tmp.object) ||
        ! gl_object_allocate(&tmp.object, (seg_u + 1) * (seg_v + 2),
                             2 * seg_u * (seg_v + 1)))
      return NULL;
    vertex = tmp.object.vertex.data;
    i = 0;
    while (i <= seg_v + 1) {
      angle_i = (f64) i * M_PI / (seg_v + 1);
      r = sin(angle_i);
      z = cos(angle_i);
      j = 0;
      while (j <= seg_u) {
        angle_j = j * M_PI * 2.0 / seg_u;
        vertex->pos_x = cos(angle_j) * r;
        vertex->pos_y = sin(angle_j) * r;
        vertex->pos_z = z;
        vertex->normal_x = vertex->pos_x;
        vertex->normal_y = vertex->pos_y;
        vertex->normal_z = vertex->pos_z;
        vertex->tex_coord_x = (f64) (seg_u - j) / seg_u;
        vertex->tex_coord_y = (f64) i / (seg_v + 1);
        vertex++;
        j++;
      }
      i++;
    }
    triangle = tmp.object.triangle.data;
    i = 0;
    while (i < seg_v + 1) {
      j = 0;
      while (j < seg_u) {
        triangle->a =  i      * (seg_u + 1) + j;
        triangle->b = (i + 1) * (seg_u + 1) + j;
        triangle->c = (i + 1) * (seg_u + 1) + j + 1;
        triangle++;
        triangle->a =  i      * (seg_u + 1) + j;
        triangle->b = (i + 1) * (seg_u + 1) + j + 1;
        triangle->c =  i      * (seg_u + 1) + j + 1;
        triangle++;
        j++;
      }
      i++;
    }
    *sphere = tmp;
    return sphere;
  }
  
  s_gl_sphere * gl_sphere_new (u32 segments_u, u32 segments_v)
  {
    s_gl_sphere *sphere;
    sphere = calloc(1, sizeof(s_gl_sphere));
    if (! sphere) {
      err_puts("gl_sphere_new: failed to allocate memory");
      return NULL;
    }
    if (! gl_sphere_init(sphere, segments_u, segments_v)) {
      free(sphere);
      return NULL;
    }
    return sphere;
  }
  
  void gl_sphere_render (const s_gl_sphere *sphere)
  {
    assert(sphere);
    gl_object_render(&sphere->object);
  }
  
  /*
  void gl_sphere_render_wireframe (const s_gl_sphere *sphere)
  {
    u32 i;
    u32 j;
    s_gl_3d *p[3];
    u32 seg_u;
    u32 seg_v;
    assert(sphere);
    seg_u = sphere->segments_u;
    seg_v = sphere->segments_v;
    // first row
    j = 0;
    while (j < seg_u + 1) {
      glBegin(GL_LINE_STRIP);
      p[0] = sphere->vertex + seg_u * seg_v;
      p[1] = sphere->vertex +  j      % seg_u;
      p[2] = sphere->vertex + (j + 1) % seg_u;
      gl_vertex_3d(p[0]);
      gl_vertex_3d(p[1]);
      gl_vertex_3d(p[2]);
      glEnd();
      j++;
    }
    // whole
    i = 1;
    while (i < seg_v) {
      j = 0;
      while (j < seg_u + 1) {
        glBegin(GL_LINE_STRIP);
        p[0] = sphere->vertex + (i - 1) * seg_u +  j      % seg_u;
        p[1] = sphere->vertex +  i      * seg_u +  j      % seg_u;
        p[2] = sphere->vertex +  i      * seg_u + (j + 1) % seg_u;
        gl_vertex_3d(p[0]);
        gl_vertex_3d(p[1]);
        gl_vertex_3d(p[2]);
        glEnd();
        j++;
      }
      i++;
    }
    glBegin(GL_LINES);
    j = 0;
    while (j < seg_u + 1) {
      p[0] = sphere->vertex + seg_u * seg_v + 1;
      p[1] = sphere->vertex + (seg_v - 1) * seg_u + j % seg_u;
      gl_vertex_3d(p[0]);
      gl_vertex_3d(p[1]);
      j++;
    }
    glEnd();
  }
  */
  

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