我正在使用OpenGL创建3D游戏,我想在窗口顶部制作一个工具栏。为此,我尝试使用SDL绘制按钮,并使用OpenGL绘制实际的游戏。这是我的代码的相关部分:
void openMainWindow(){
SDL_Surface *screen;
SDL_Event event;
SDL_Rect position;
SDL_Init(SDL_INIT_VIDEO);
putenv("SDL_VIDEO_CENTERED=center");
SDL_WM_SetCaption("Example",NULL);
SDL_WM_SetIcon(IMG_Load("icon.png"),NULL);
screen = SDL_SetVideoMode(832,487,32,SDL_HWSURFACE | SDL_OPENGL);
glLoadIdentity();
gluPerspective(70,(double)832/487,1,1000);
//Some things to initialize the window
int continue = 1;
while(continue){
SDL_PollEvent(&event);
switch(event.type){
//Events
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBegin(GL_QUADS);
//Draw a square
glEnd();
//Draw more things the same way
glFlush();
SDL_GL_SwapBuffers();
SDL_Surface *button1 = SDL_CreateRGBSurface(SDL_HWSURFACE,50,50,32,0,0,0,0);
SDL_FillRect(button1,NULL,SDL_MapRGB(screen->format,50,50,50);
position.x = 8;
position.y = 8;
SDL_BlitSurface(button1,NULL,screen,&position);
SDL_Flip(screen);
}
SDL_Quit();
}
问题在于,当调用此函数时,过程结束并返回3(这意味着有错误)。因此,我尝试使用OpenGL绘制按钮,如下所示:
void openMainWindow(){
//Everything before the while loop is the same as in the other code
int continue = 1;
while(continue){
SDL_PollEvent(&event);
switch(event.type){
//Events
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBegin(GL_QUADS);
//Draw a square
glEnd();
//Draw more things the same way
glDisable(GL_DEPTH_TEST);
glLoadIdentity();
glBegin(GL_QUADS); //Draw the button
glColor3ub(50,50,50);
glVertex2d(-0.5,-0.5);
glVertex2d(-0.5,0.5);
glVertex2d(0.5,0.5);
glVertex2d(0.5,-0.5);
glEnd();
glEnable(GL_DEPTH_TEST);
glFlush();
SDL_GL_SwapBuffers();
}
SDL_Quit();
}
我知道第二个代码应该使按钮在窗口中居中,但是我使用此代码只是为了测试它是否有效(这是不行的,这就是为什么我要发布此问题)。
使用第二个代码,3D事物将按原样出现在窗口中,但是我看不到任何按钮。如何在3D OpenGL窗口中放置2D按钮?
第二个代码通过在绘制2D按钮之前添加以下内容来起作用:
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glDisable(GL_DEPTH_TEST);
glLoadIdentity();
以及绘制2D按钮后的以下代码:
glEnable(GL_DEPTH_TEST);
gluPerspective(70,(double)640/480,0.5,INFINITE); //These parameters have to be the same as the ones used for gluPerspective when initializing the 3D
gluLookAt(0,0,3,1,0,3,0,0,0.01); //Where you want to position the camera and where you want to look at
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
这是有效的完整代码:
void openMainWindow(){
//Everything before the while loop is the same as in the other code
int continue = 1;
while(continue){
SDL_PollEvent(&event);
switch(event.type){
//Events
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBegin(GL_QUADS);
//Draw a square
glEnd();
//Draw more things the same way
glLoadIdentity();
glMatrixMode(GL_PROJECTION);
glDisable(GL_DEPTH_TEST);
glLoadIdentity();
glBegin(GL_QUADS); //Draw the button
glColor3ub(50,50,50);
glVertex2d(-0.5,-0.5);
glVertex2d(-0.5,0.5);
glVertex2d(0.5,0.5);
glVertex2d(0.5,-0.5);
glEnd();
glEnable(GL_DEPTH_TEST);
gluPerspective(70,(double)640/480,0.5,INFINITE); //These parameters have to be the same as the ones used for gluPerspective when initializing the 3D
gluLookAt(0,0,3,1,0,3,0,0,0.01); //Where you want to position the camera and where you want to look at
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glFlush();
SDL_GL_SwapBuffers();
}
SDL_Quit();
}
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