Question

讨厌做一个＆＃34;找到我的错误＆＃34;发布，但互联网似乎严重缺乏任何超简单的OpenGL ES2三角绘图的例子。从技术上讲，这是使用OpenGL 2.1，但OpenGL ES2只是其中的一部分......对吗？

无论如何，这是我的代码（我删除了记录/错误检查，我知道它通过了）

#include <SDL.h>
#include <SDL_opengl.h>

int main(int argc, char* argv[])
{    
  SDL_Init( SDL_INIT_VIDEO | SDL_INIT_EVENTS);

  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION,2);
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION,1);

  SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL,1);
  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1);

  SDL_Window* window = SDL_CreateWindow("Test", 0,0,100,100, SDL_WINDOW_OPENGL);
  SDL_GLContext gl = SDL_GL_CreateContext(window);

  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LESS);

  GLuint gl_program_id;
  GLuint gl_vs_id;
  GLuint gl_fs_id;
  GLuint gl_pos_attrib_id;
  GLuint gl_pos_buff_id;

  char vs_file[2048]; //assume I successfully loaded vertex shader code into this array
  char *vs_file_p = &vs_file[0];
  char fs_file[2048]; //assume I successfully loaded fragment shader code into this array
  char *fs_file_p = &fs_file[0];

  gl_vs_id = glCreateShader(GL_VERTEX_SHADER);
  glShaderSource(gl_vs_id, 1, &vs_file_p, NULL);
  glCompileShader(gl_vs_id);

  gl_fs_id = glCreateShader(GL_FRAGMENT_SHADER);
  glShaderSource(gl_fs_id, 1, &fs_file_p, NULL);
  glCompileShader(gl_fs_id);

  gl_program_id = glCreateProgram();
  glAttachShader(gl_program_id, gl_vs_id);
  glAttachShader(gl_program_id, gl_fs_id);
  glLinkProgram(gl_program_id);

  glDeleteShader(gl_vs_id);
  glDeleteShader(gl_fs_id);

  glUseProgram(gl_program_id);

  gl_pos_attrib_id = glGetAttribLocation(gl_program_id, "position");

  float verts[] = {0.0,0.0,0.5,1.0,1.0,0.0};
  glGenBuffers(1, &gl_pos_buff_id);
  glBindBuffer(GL_ARRAY_BUFFER, gl_pos_buff_id);
  glBufferData(GL_ARRAY_BUFFER, sizeof(float)*2*3, verts, GL_STATIC_DRAW);
  glVertexAttribPointer(gl_pos_attrib_id, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
  glEnableVertexAttribArray(gl_pos_attrib_id);

  glViewport(0,0,100,100);
  glClearColor(0.,0.,0.,1.);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glUseProgram(gl_program_id);

  glBindBuffer(GL_ARRAY_BUFFER, gl_pos_buff_id);
  glBufferData(GL_ARRAY_BUFFER, sizeof(float)*2*3, verts, GL_STATIC_DRAW);
  glVertexAttribPointer(gl_pos_attrib_id, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
  glEnableVertexAttribArray(gl_pos_attrib_id);

  glDrawArrays(GL_TRIANGLES,0,3*3);

  SDL_GL_SwapWindow(window);

  //while loop waiting on input to quit goes here...

  SDL_GL_DeleteContext(gl);
  SDL_Quit();
  exit(0);
  return 0;
}

我的着色器如下：

顶点：

#version 110

attribute vec2 position;

void main()
{
  gl_Position = vec4(position,1.,1.);
}

片段：

#version 110

void main()
{
  gl_FragColor = vec4(1.);
}

另一个注意事项是所有着色器都编译，程序编译，上下文和窗口创建都顺利完成。它最终只有一个黑色的100x100px窗口。任何帮助将不胜感激！

（另外，如果有人可以在opengl es2上推荐体面，一致，直接的文档资源，这将非常棒。版本/平台之间的文档很多不一致。谢谢！）

OpenGL ES2黑屏（C ++，OSX，SDL2）

0 个答案: