问题
I use SFML to create the window.
In this screenshot the cube should be behind the pyramid but it just doesn't work.
Here is the minimal code I used:
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
#include <SFML/Graphics.hpp>
#include "ResourcePath.hpp"
void resize();
void drawScene();
void initGL();
float rtri = 0;
float rquad = 0;
float z = -10.0f;
int main (int argc, const char * argv[])
{
// Create the main window
sf::RenderWindow *window = new sf::RenderWindow();
window->Create( sf::VideoMode( 800, 600, 32 ), "Collision Detection", sf::Style::Close );
sf::Event event;
bool run = true;
initGL();
resize();
while( run ) {
window->PollEvent( event );
if( event.Type == sf::Event::Closed ) {
run = false;
}
drawScene();
window->Display();
// z+= 0.001f;
}
return EXIT_SUCCESS;
}
void resize() {
glViewport(0,0, 800,600);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// Calculate The Aspect Ratio Of The Window
gluPerspective(45.0f,800/600,0.1f,100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void drawScene() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity(); // Reset The Current Modelview Matrix
glTranslatef(0.0f,0.0f,-6.0f); // Move Left 1.5 Units And Into The Screen 6.0
glRotatef(rtri,0.0f,1.0f,0.0f); // Rotate The Triangle On The Y axis ( NEW )
glBegin(GL_TRIANGLES);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f( 0.0f, 1.0f, 0.0f);
glColor3f(0.0f,1.0f,0.0f);
glVertex3f(-1.0f,-1.0f, 1.0f);
glColor3f(0.0f,0.0f,1.0f);
glVertex3f( 1.0f,-1.0f, 1.0f);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f( 0.0f, 1.0f, 0.0f);
glColor3f(0.0f,0.0f,1.0f);
glVertex3f( 1.0f,-1.0f, 1.0f);
glColor3f(0.0f,1.0f,0.0f);
glVertex3f( 1.0f,-1.0f, -1.0f);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f( 0.0f, 1.0f, 0.0f);
glColor3f(0.0f,1.0f,0.0f);
glVertex3f( 1.0f,-1.0f, -1.0f);
glColor3f(0.0f,0.0f,1.0f);
glVertex3f(-1.0f,-1.0f, -1.0f);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f( 0.0f, 1.0f, 0.0f);
glColor3f(0.0f,0.0f,1.0f);
glVertex3f(-1.0f,-1.0f,-1.0f);
glColor3f(0.0f,1.0f,0.0f);
glVertex3f(-1.0f,-1.0f, 1.0f);
glEnd();
glLoadIdentity(); // Reset The Current Modelview Matrix
glTranslatef(0.0f,0.0f,z); // Move Right 1.5 Units And Into The Screen 7.0
glRotatef(rquad,1.0f,1.0f,z); // Rotate The Quad On The X axis ( NEW )
glBegin(GL_QUADS);
glColor3f(0.0f,1.0f,0.0f);
glVertex3f( 1.0f, 1.0f,-1.0f);
glVertex3f(-1.0f, 1.0f,-1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glColor3f(1.0f,0.5f,0.0f);
glVertex3f( 1.0f,-1.0f, 1.0f);
glVertex3f(-1.0f,-1.0f, 1.0f);
glVertex3f(-1.0f,-1.0f,-1.0f);
glVertex3f( 1.0f,-1.0f,-1.0f);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f,-1.0f, 1.0f);
glVertex3f( 1.0f,-1.0f, 1.0f);
glColor3f(1.0f,1.0f,0.0f);
glVertex3f( 1.0f,-1.0f,-1.0f);
glVertex3f(-1.0f,-1.0f,-1.0f);
glVertex3f(-1.0f, 1.0f,-1.0f);
glVertex3f( 1.0f, 1.0f,-1.0f);
glColor3f(0.0f,0.0f,1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f,-1.0f);
glVertex3f(-1.0f,-1.0f,-1.0f);
glVertex3f(-1.0f,-1.0f, 1.0f);
glColor3f(1.0f,0.0f,1.0f);
glVertex3f( 1.0f, 1.0f,-1.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glVertex3f( 1.0f,-1.0f, 1.0f);
glVertex3f( 1.0f,-1.0f,-1.0f);
glEnd(); // Done Drawing The Quad
rtri+=0.2f; // Increase The Rotation Variable For The Triangle ( NEW )
rquad-=0.15f;
z-=0.01;
}
void initGL() {
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background
glClearDepth(1.0f); // Depth Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glEnable( GL_CULL_FACE );
/* Position the camera */
glTranslatef(0, 0, -5);
}
I've tried different depth functions, GL_LESS, GL_EQUAL, I've tried them all. Also enabling and disabling depth testing on different places, nothing seems to work.
I'm running Mac OS X 10.7 ( Lion ), not sure if that is important, though I didn't seem to have any trouble with these kind of things before upgrading.
回答1:
Your code looks okay. I suspect that your window simply does not have a depth buffer. You're using sf::RenderWindow, whose documentation says (emphasis mine):
Simple wrapper for
sf::Windowthat allows easy 2D rendering.
I don't know SFML, but this tutorial suggests to create your window like this:
sf::WindowSettings Settings;
Settings.DepthBits = 24; // Request a 24 bits depth buffer
Settings.StencilBits = 8; // Request a 8 bits stencil buffer
Settings.AntialiasingLevel = 2; // Request 2 levels of antialiasing
sf::Window App(sf::VideoMode(800, 600, 32), "SFML OpenGL", sf::Style::Close, Settings);
You could set StencilBits and AntialiasingLevel to 0 since this example doesn't need them.
回答2:
In latest version of SFML WindowSettings replaced by ContextSettings. Depth settings can be configured as.
//Configuring SFML window
sf::ContextSettings window_settings;
window_settings.depthBits = 24; // Request a 24-bit depth buffer
window_settings.stencilBits = 8; // Request a 8 bits stencil buffer
window_settings.antialiasingLevel = 2; // Request 2 levels of antialiasing
// Opening SFML window
sf::Window window(sf::VideoMode(800, 600), "Title", sf::Style::Resize | sf::Style::Close, window_settings);
glewExperimental = GL_TRUE;
// Initializing glew and openGL
glewInit();
glViewport(0, 0, 800, 600);
// Enabling Depth
glEnable(GL_DEPTH_TEST);
来源：https://stackoverflow.com/questions/9045843/cant-get-depth-testing-to-work-in-opengl