OpenGL深度问题

Question

我在OpenGL中渲染深度有问题

以下代码是发生问题的代码的简单示例.它在同一个地方渲染出2个梯形,其中一个旋转.但旋转的一个总是显示在顶部,即使旋转时应该在第一个梯形后面.

我想我通过初始化OpenGL搞砸了一些东西.此外,当搜索stackoverflow时,我发现有人建议执行以下代码并查看输出的帖子.

int depth;
glGetIntegerv(GL_DEPTH_BITS, &depth);
printf("%i bits depth", depth);

好的输出是,0位深度,这是不好我猜:(

我正在使用glfw库在xCode上开发Mac

#include <GL/glfw.h>
#include <stdlib.h>

int main( void )
{
   int running = GL_TRUE;

   if( !glfwInit() )
   {
      exit( EXIT_FAILURE );
   }

   // Open an OpenGL window
   if( !glfwOpenWindow( 640,480, 0,0,0,0,0,0, GLFW_WINDOW ))
   {
      glfwTerminate();
      exit( EXIT_FAILURE );
   }

   glEnable(GL_DEPTH_TEST);

   float angle = 0;

   // Main loop
   while( running )
   {

      double elapsedTime = glfwGetTime();
      glfwSetTime(0);
      angle += 90 * elapsedTime;

      // OpenGL rendering goes here...
      glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

      glMatrixMode(GL_MODELVIEW);
      glLoadIdentity();

      glPushMatrix(); //Save the transformations performed thus far
      glColor3f(1.0f, 1.0, 0.0);
      glTranslatef(0.0f, 0.0f, 0.0f); //Move to the center of the trapezoid
      //glRotatef(angle, 0.0f, 1.0f, 0.0f); //Rotate about the y-axis
      glBegin(GL_QUADS);

      //Trapezoid
      glVertex3f(-0.7f, -0.5f, 0.0f);
      glVertex3f(0.7f, -0.5f, 0.0f);
      glVertex3f(0.4f, 0.5f, 0.0f);
      glVertex3f(-0.4f, 0.5f, 0.0f);

      glEnd();

      glPopMatrix();

      glPushMatrix(); //Save the transformations performed thus far
      glColor3f(1.0f, 0.0, 0.0);
      glTranslatef(0.0f, 0.0f, 0.0f); //Move to the center of the trapezoid
      glRotatef(angle, 0.0f, 1.0f, 0.0f); //Rotate about the y-axis
      glBegin(GL_QUADS);

      //Trapezoid
      glVertex3f(-0.7f, -0.5f, 0.0f);
      glVertex3f(0.7f, -0.5f, 0.0f);
      glVertex3f(0.4f, 0.5f, 0.0f);
      glVertex3f(-0.4f, 0.5f, 0.0f);

      glEnd();

      glPopMatrix(); //Undo the move to the center of the trapezoid

      glfwSwapBuffers();

      // Check if ESC key was pressed or window was closed
      running = !glfwGetKey( GLFW_KEY_ESC ) &&
      glfwGetWindowParam( GLFW_OPENED );
   }

   // Close window and terminate GLFW
   glfwTerminate();
   // Exit program
   exit( EXIT_SUCCESS );
}

Answer 1

if(!glfwOpenWindow(640,480,0,0,0,0,0,0,GLFW_WINDOW))

为什么你通过所有这些零？那些参数很重要.该GLFW参考文档(PDF)显示,这些参数描述了你多少位想要的颜色,深度和模板.倒数第二个零是深度位的数量.你为帧缓冲要求了0位深度,这就是你得到的.

你不能责怪API做你所要求的;)

一个更合理的命令是:

if( !glfwOpenWindow( 640,480, 8, 8, 8, 8, 24, 8, GLFW_WINDOW ))

这为RGBA提供了8位,深度为24位,模板为8位.