OpenGL在2個紋理之間切換

Question

我有一個正在處理的OpenGL項目，我需要將這2個PNG文件綁定到兩個不同的對象。 到目前為止，我所擁有的只是將最新加載的紋理綁定到所有內容。

我這樣加載我的PNG：

void load_texture(GLuint texture, const char* filename, int x, int y) {
  Fl_PNG_Image image(filename);    // load texturemap
  glBindTexture(GL_TEXTURE_2D, texture);
  glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE , GL_MODULATE);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  gluBuild2DMipmaps(GL_TEXTURE_2D, 3, x, y, GL_RGB, GL_UNSIGNED_BYTE, image.data()[0]);
}

在初始化中，我得到了這個：

GLuint* textures;
...
int main(void) {
   ...
   textures = new GLuint[2];
   glGenTextures(2, textures);
   ...

在我的繪制函數中，我正在這樣做：

  glEnable(GL_TEXTURE_2D);      
  load_texture(textures[1], "wood.png", 64, 64);
  load_texture(textures[0], "brick.png", 128, 128);

  for (unsigned int x = 0; x < x_size; ++x) {
    for (unsigned int z = 0; z < z_size; ++z) {
    char type = m->get_object(x,z);
    switch (type) {
      case 'W': {
      // Front Face
        glBegin(GL_QUADS);
        glBindTexture(GL_TEXTURE_2D, textures[0]);
        glColor3f(1.0, 1.0, 1.0);
        glTexCoord2f(0.0, 1.0); glVertex3f(x    , 1, z + 1);
        glTexCoord2f(1.0, 1.0); glVertex3f(x + 1, 1, z + 1);
        glTexCoord2f(1.0, 0.0); glVertex3f(x + 1, 0, z + 1);
        glTexCoord2f(0.0, 0.0); glVertex3f(x    , 0, z + 1);
        // Back Face
        glTexCoord2f(0.0, 1.0); glVertex3f(x + 1, 1, z);
        glTexCoord2f(1.0, 1.0); glVertex3f(x    , 1, z);
        glTexCoord2f(1.0, 0.0); glVertex3f(x    , 0, z);
        glTexCoord2f(0.0, 0.0); glVertex3f(x + 1, 0, z);
        // Right face
        glTexCoord2f(0.0, 1.0); glVertex3f(x + 1, 1, z + 1);
        glTexCoord2f(1.0, 1.0); glVertex3f(x + 1, 1, z    );
        glTexCoord2f(1.0, 0.0); glVertex3f(x + 1, 0, z    );
        glTexCoord2f(0.0, 0.0); glVertex3f(x + 1, 0, z + 1);
        // Left Face
        glTexCoord2f(0.0, 1.0); glVertex3f(x, 1, z    );
        glTexCoord2f(1.0, 1.0); glVertex3f(x, 1, z + 1);
        glTexCoord2f(1.0, 0.0); glVertex3f(x, 0, z + 1);
        glTexCoord2f(0.0, 0.0); glVertex3f(x, 0, z    );
        glEnd();
        break;
      }
      case ' ': {
        // Draw floor
        glBegin(GL_QUADS);
        glBindTexture(GL_TEXTURE_2D, textures[1]);
        glTexCoord2f(0.0, 0.0); glVertex3f(x    , 0, z    );
        glTexCoord2f(0.0, 1.0); glVertex3f(x    , 0, z + 1);
        glTexCoord2f(1.0, 1.0); glVertex3f(x + 1, 0, z + 1);
        glTexCoord2f(1.0, 0.0); glVertex3f(x + 1, 0, z    );
        glEnd();

        // Draw roof
        glBegin(GL_QUADS);
        glBindTexture(GL_TEXTURE_2D, textures[0]);
        glTexCoord2f(0.0, 0.0); glVertex3f(x    , 1, z    );
        glTexCoord2f(0.0, 1.0); glVertex3f(x    , 1, z + 1);
        glTexCoord2f(1.0, 1.0); glVertex3f(x + 1, 1, z + 1);
        glTexCoord2f(1.0, 0.0); glVertex3f(x + 1, 1, z    );
        glEnd();
        break;
      }
     default:
        break;
     }
   }

看起來像這樣：

但是wood.png看起來像這樣：

並且應在地板和天花板上進行渲染。 任何見解將不勝感激。 預先感謝，馬克斯

Answer 1

您不能在glBegin和glEnd之間調用glBindTexture 。

如果在glBegin的執行和glEnd的相應執行之間執行glBindTexture，則生成GL_INVALID_OPERATION。

請參閱glBindTexture文檔 。