terrain

Real-time terrain generation using marching cubes
git clone git://git.christianermann.dev/terrain
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mesh.c (2225B)

      1 #include "mesh.h"
      2 
      3 #include "glad/glad.h"
      4 
      5 #include <stdlib.h>
      6 
      7 void Mesh_init(Mesh *m, u32 vertex_count, u32 index_count)
      8 {
      9     m->vertex_capacity = vertex_count;
     10     m->vertex_count = 0;
     11 
     12     m->index_capacity = index_count;
     13     m->index_count = 0;
     14 
     15     glGenVertexArrays(1, &m->vao);
     16     glBindVertexArray(m->vao);
     17 
     18     glGenBuffers(1, &m->vbo);
     19     glBindBuffer(GL_ARRAY_BUFFER, m->vbo);
     20     glBufferData(
     21             GL_ARRAY_BUFFER,
     22             sizeof *m->vertices * vertex_count,
     23             NULL,
     24             GL_STATIC_DRAW
     25     );
     26 
     27     glVertexAttribPointer(
     28             0,
     29             3,
     30             GL_FLOAT,
     31             GL_FALSE,
     32             sizeof(Vertex),
     33             (GLvoid*)0
     34     );
     35     glEnableVertexAttribArray(0);
     36 
     37     glVertexAttribPointer(
     38             1,
     39             3,
     40             GL_FLOAT,
     41             GL_FALSE,
     42             sizeof(Vertex),
     43             (GLvoid*)sizeof(Vec3)
     44     );
     45     glEnableVertexAttribArray(1);
     46 
     47     glGenBuffers(1, &m->ebo);
     48     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m->ebo);
     49     glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof *m->indices * index_count,
     50             NULL, GL_STATIC_DRAW);
     51 
     52     glBindVertexArray(0);
     53 }
     54 
     55 void Mesh_free(Mesh *m)
     56 {
     57     m->vertex_capacity = 0;
     58     m->vertex_count = 0;
     59 
     60     m->index_capacity = 0;
     61     m->index_count = 0;
     62 
     63     Mesh_unmapBuffers(m);
     64 
     65     glDeleteVertexArrays(1, &m->vao);
     66     glDeleteBuffers(1, &m->vbo);
     67     glDeleteBuffers(1, &m->ebo);
     68 }
     69 
     70 void Mesh_mapBuffers(Mesh *m)
     71 {
     72     glBindBuffer(GL_ARRAY_BUFFER, m->vbo);
     73     m->vertices = glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
     74 
     75     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m->ebo);
     76     m->indices = glMapBuffer(GL_ELEMENT_ARRAY_BUFFER, GL_WRITE_ONLY);
     77 
     78     m->buffers_mapped = true;
     79 }
     80 
     81 void Mesh_unmapBuffers(Mesh *m)
     82 {
     83     glBindBuffer(GL_ARRAY_BUFFER, m->vbo);
     84     glUnmapBuffer(GL_ARRAY_BUFFER);
     85     m->vertices = NULL;
     86 
     87     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m->ebo);
     88     glUnmapBuffer(GL_ELEMENT_ARRAY_BUFFER);
     89     m->indices = NULL;
     90 
     91     m->buffers_mapped = false;
     92 }
     93 
     94 void Mesh_draw(const Mesh *m)
     95 {
     96     if (!m->buffers_mapped)
     97     {
     98         glBindVertexArray(m->vao);
     99         glDrawElements(GL_TRIANGLES, m->index_count, GL_UNSIGNED_INT, 0);
    100         glBindVertexArray(0);
    101     }
    102 }