我在使用OpenGL渲染深度方面遇到了问题。
以下代码是出现问题的简单示例。它在同一位置呈现了两个梯形,其中一个在旋转。但是旋转的那个始终显示在顶部,即使在旋转时应该在第一个梯形后面。
我猜我在初始化OpenGL时弄错了什么。在搜索stackoverflow时,我找到了一篇帖子,有人建议执行以下代码并查看输出。
int depth;
glGetIntegerv(GL_DEPTH_BITS, &depth);
printf("%i bits depth", depth);
输出结果是0位深度,我猜这不太好 :(
我正在Mac上使用xCode和glfw库进行开发。
#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 );
}