我在 PC 上运行此代码（在 code::blocks 10.05 中编译）
当我使用 GLUT（GL Utiltiy Toolkit）做基本的 OpenGL 代码时，一切正常。
现在，当我尝试更改平移函数的 z 轴（第三个参数）时，我正在通过 SDL 框架运行 OpenGL 代码，几何图元（四边形）的位置似乎没有深度，并且要么显示覆盖当深度达到某一点时，整个屏幕或完全消失。
我错过了什么吗？：/
#include <sdl.h>
#include <string>
#include "sdl_image.h"
#include "SDL/SDL_opengl.h"
#include <gl\gl.h>
// Declare Constants
const int FRAMES_PER_SECOND = 60;
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;
// Create Event Listener
SDL_Event event;
// Declare Variable Used To Control How Deep Into The Screen The Quad Is
GLfloat zpos(0);
// Loop Switches
bool gamestarted(false);
bool exited(false);
// Prototype For My GL Draw Function
void drawstuff();
// Code Begins
void init_GL() {
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); // Really Nice Perspective Calculations
glViewport(0, 0, 640, 513); // Viewport Change
glOrtho(0, 640, 0, 513, -1.0, 1.0); // Puts Stuff Into View
}
bool init() {
SDL_Init(SDL_INIT_EVERYTHING);
SDL_SetVideoMode(640, 513, 32, SDL_OPENGL);
return true;
}
void drawstuff() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glTranslatef(0.0f, 0.0f, zpos);
glColor3f(0.5f,0.5f,0.5f);
glBegin(GL_QUADS);
glVertex3f(-1.0f, 1.0f, 0.0f);
glVertex3f( 1.0f, 1.0f, 0.0f);
glVertex3f( 1.0f,-1.0f, 0.0f);
glVertex3f(-1.0f,-1.0f, 0.0f);
glEnd();
}
int main (int argc, char* args[]) {
init();
init_GL();
while(exited == false) {
while( SDL_PollEvent( &event ) ) {
if( event.type == SDL_QUIT ) {
exited = true;
}
if( event.type == SDL_MOUSEBUTTONDOWN ) {
zpos-=.1;
}
}
glClear( GL_COLOR_BUFFER_BIT);
drawstuff();
SDL_GL_SwapBuffers();
}
SDL_Quit();
return 0;
}