我尝试在Windows中使用OpenGL渲染多维数据集。但显示窗口是黑色的。我启用了Z-Buffer，我清除了glClear函数中的深度位等。但没有运气。问题是我遵循的每个示例或文档都是不完整的，或者省略了一些信息，而且我现在非常非常困惑。我不知道我做得对，我做错了什么。
我想要的只是显示一个立方体，知道渲染器已准备好用于3D图形（我可以毫无问题地显示2D图形）。没别了。
这是我主程序的代码：
#include "demo.h"
#include "renderfunc.c"
HDC hDC;
HGLRC hRC;
void enableGL(HWND hWnd)
{
hDC = GetDC(hWnd);
int nPixelFormat;
static PIXELFORMATDESCRIPTOR pfd = {
sizeof(PIXELFORMATDESCRIPTOR),
1,
PFD_DRAW_TO_WINDOW |
PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER,
PFD_TYPE_RGBA,
24,
0,0,0,0,0,0,
0,0,
0,0,0,0,0,
32,
0,
0,
PFD_MAIN_PLANE,
0,
0,0,0 };
if(!hDC)
{
MessageBox(hWnd,L"Can't Create A GL Device Context.",L"ERROR",MB_OK|MB_ICONEXCLAMATION);
return;
}
nPixelFormat = ChoosePixelFormat(hDC, &pfd);
if(!nPixelFormat)
{
MessageBox(hWnd,L"Can't find a proper Pixel Format.",L"ERROR",MB_OK|MB_ICONEXCLAMATION);
return;
}
SetPixelFormat(hDC, nPixelFormat, &pfd);
/* Those lines has to be here*/
hRC = wglCreateContext(hDC);
wglMakeCurrent(hDC,hRC);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
/* UNCOMMENT THIS SECTION FOR 3D */
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_EQUAL); //In some examples this is GL_LESS
glDepthMask(GL_TRUE);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); //Accurate perspective calculations
return;
}
GLvoid ChangeSize(GLsizei width, GLsizei height)
{
if(height==0)
height=1;
glViewport(0,0,width,height);
//glLoadIdentity();
/* THIS SECTION IS FOR 3D GRAPHICS */
/* Comment glLoadIdentity above, and uncomment this section */
/* If you enable Z-buffer */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, (GLfloat)width/(GLfloat)height,0.1f,100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
return;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch (msg)
{
case WM_CREATE:
enableGL(hWnd);
return 0;
case WM_CLOSE:
PostQuitMessage(0);
return 0;
case WM_DESTROY:
ReleaseDC(hWnd,hDC);
wglMakeCurrent(hDC, NULL);
wglDeleteContext(hRC);
PostQuitMessage(0);
return 0;
case WM_KEYDOWN:
switch(wParam)
{
case VK_ESCAPE:
PostQuitMessage(0);
return 0;
}
return 0;
case WM_PAINT:
glClearColor( 0.0f, 0.0f, 0.0f, 1.0f );
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
/* GL ANIMATION GOES HERE */
//Change this for whatever you want to render
renderCubeTest();
/* -------------------- */
SwapBuffers(hDC);
ValidateRect(hWnd, NULL);
return 0;
case WM_SIZE:
ChangeSize(LOWORD(lParam), HIWORD(lParam));
return 0;
default:
return DefWindowProc(hWnd, msg, wParam, lParam);
}
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iCmdShow)
{
WNDCLASS wc;
HWND hWnd;
MSG msg;
//String with the name of the class of our window
LPCTSTR classname = L"OpenGL";
//String with the title of our window
LPCTSTR windowtitle = L"Cubes Demo By Ninjihaku Software";
wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
wc.lpfnWndProc = (WNDPROC) WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
//wc.hIcon = (HICON) LoadImage(hInstance, MAKEINTRESOURCE(IDI_APPICON), IMAGE_ICON, 0, 0, LR_DEFAULTSIZE | LR_DEFAULTCOLOR | LR_SHARED);
wc.hIcon = NULL;
wc.hCursor = (HCURSOR) LoadImage(NULL, IDC_ARROW, IMAGE_CURSOR, 0, 0, LR_SHARED);
wc.hbrBackground = NULL;
wc.lpszMenuName = NULL;
wc.lpszClassName = classname;
if(RegisterClass(&wc) == 0)
return false;
//hWnd = CreateWindow(classname, windowtitle, WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN | WS_CLIPSIBLINGS, 100, 100, 640, 480, NULL, NULL, hInstance, NULL);
hWnd = CreateWindowEx(WS_EX_APPWINDOW | WS_EX_WINDOWEDGE, classname, windowtitle, WS_OVERLAPPEDWINDOW | WS_CLIPSIBLINGS | WS_CLIPCHILDREN, 0, 0, 640, 480, NULL, NULL, hInstance, NULL);
if(hWnd == NULL)
return FALSE;
ShowWindow(hWnd, SW_SHOW);
UpdateWindow(hWnd);
while(GetMessage(&msg, NULL, 0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
DestroyWindow(hWnd);
return (int) msg.wParam;
}
然后renderfunc.c中包含renderCubeTest（）函数：
void renderCubeTest()
{
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix();
glTranslatef(1.5f, 0.0f, -7.0f); // Move right and into the screen
glBegin(GL_QUADS); // Begin drawing the color cube with 6 quads
// Top face (y = 1.0f)
// Define vertices in counter-clockwise (CCW) order with normal pointing out
glColor3f(0.0f, 1.0f, 0.0f); // Green
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);
// Bottom face (y = -1.0f)
glColor3f(1.0f, 0.5f, 0.0f); // Orange
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);
// Front face (z = 1.0f)
glColor3f(1.0f, 0.0f, 0.0f); // Red
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);
// Back face (z = -1.0f)
glColor3f(1.0f, 1.0f, 0.0f); // Yellow
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);
// Left face (x = -1.0f)
glColor3f(0.0f, 0.0f, 1.0f); // Blue
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);
// Right face (x = 1.0f)
glColor3f(1.0f, 0.0f, 1.0f); // Magenta
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(); // End of drawing color-cube
glFlush();
glPopMatrix();
return;
}
我希望有人可以帮助我并告诉我这有什么问题。
答案 0 :(得分：5)
glDepthFunc(GL_EQUAL);
我怀疑这是问题 - 它基本上是告诉OpenGL，如果新像素的深度值等于当前像素的深度值，则只应将像素渲染到屏幕。这肯定不是你想要的。
相反，您应该使用GL_LEQUAL（注意“EQUAL”之前的“L”）或GL_LESS，因为这些是正常的比较函数。