我尝试在两个类之间共享 HPBUFFERARB：TGLForm 和 TGLForm2。
（我尝试过 FBO，但有一个旧的 Borland Builder 6 版本，我无法使用 FBO 进行管理）
我的目标是在两个 openGL 窗口中显示相同的缓冲区。
所以我在第一个 Form 之外声明了这个对象：
struct GLRenderToTexture
{
struct
{
HDC hdc;
HGLRC hGlRc;
HPBUFFERARB hBuffer;
PFNWGLGETEXTENSIONSSTRINGARBPROC wglGetExtensionsStringARB;
PFNWGLCHOOSEPIXELFORMATARBPROC wglChoosePixelFormatARB;
PFNWGLCREATEPBUFFERARBPROC wglCreatePbufferARB;
PFNWGLGETPBUFFERDCARBPROC wglGetPbufferDCARB;
PFNWGLQUERYPBUFFERARBPROC wglQueryPbufferARB;
PFNWGLDESTROYPBUFFERARBPROC wglDestroyPbufferARB;
PFNWGLRELEASEPBUFFERDCARBPROC wglReleasePbufferDCARB;
PFNWGLBINDTEXIMAGEARBPROC wglBindTexImageARB;
PFNWGLRELEASETEXIMAGEARBPROC wglReleaseTexImageARB;
} wgl;
unsigned int texture; // the texture we're going to render to
};
GLRenderToTexture RTT;
我初始化它以便具有与第一个 Form 相同的像素格式：
void __fastcall TGLForm::FormCreate(TObject *Sender)
{
ghDC = GetDC(Handle);
if (!bSetupPixelFormat(ghDC)) Close();
ghRC = wglCreateContext(ghDC);
wglMakeCurrent(ghDC, ghRC);
InitializeGL();
int pixelFormats;
int intAttrs[32] ={WGL_RED_BITS_ARB,8,WGL_GREEN_BITS_ARB,8,WGL_BLUE_BITS_ARB,8,WGL_ALPHA_BITS_ARB,8,WGL_DRAW_TO_PBUFFER_ARB, GL_TRUE,WGL_BIND_TO_TEXTURE_RGBA_ARB, GL_TRUE,WGL_SUPPORT_OPENGL_ARB,GL_TRUE,WGL_ACCELERATION_ARB,WGL_FULL_ACCELERATION_ARB,WGL_DOUBLE_BUFFER_ARB,GL_FALSE,0}; // 0 terminate the list
unsigned int numFormats = 0;
// get an acceptable pixel format to create the PBuffer with
if (RTT.wgl.wglChoosePixelFormatARB(ghDC, intAttrs, NULL, 1, &pixelFormats, &numFormats)==FALSE)
AnsiString error = AnsiString().sprintf("wglChoosePixelFormatARB returned %i", GetLastError()); // GetLastError will tell us why it failed
//Set some p-buffer attributes so that we can use this p-buffer as a 2d texture target
const int attributes[]= {WGL_TEXTURE_FORMAT_ARB, WGL_TEXTURE_RGBA_ARB, // p-buffer will have RBA texture format
WGL_TEXTURE_TARGET_ARB, WGL_TEXTURE_2D_ARB, 0}; // Of texture target will be GL_TEXTURE_2D
// the size of the PBuffer must be the same size as the texture
RTT.wgl.hBuffer= RTT.wgl.wglCreatePbufferARB(ghDC, pixelFormats, ClientWidth, ClientHeight, attributes);
RTT.wgl.hdc= RTT.wgl.wglGetPbufferDCARB(RTT.wgl.hBuffer);
RTT.wgl.hGlRc= wglCreateContext(RTT.wgl.hdc);
wglMakeCurrent(NULL,NULL);
}
这是我的第一个 DrawScene：“PaintGL()”绘图完美地在此表单上绘制：
void TGLForm::DrawSceneForm1()
{
wglMakeCurrent(ghDC, ghRC);
ClientWidth = 1920;
ClientHeight = 1080;
// create a texture to use as the backbuffer
glGenTextures(1, &RTT.texture);
glBindTexture(GL_TEXTURE_2D, RTT.texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
// make sure this is the same color format as the screen
glTexImage2D(GL_TEXTURE_2D, 0, 4, ClientWidth, ClientHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
// switch to the texture context
wglMakeCurrent(RTT.wgl.hdc, RTT.wgl.hGlRc);
glEnable(GL_TEXTURE_2D); // Enable Texture Mapping
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE);
glClear(GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClearColor(0,0,0,1);
glClear(GL_COLOR_BUFFER_BIT);
glDisable(GL_TEXTURE_2D);
// switch back to the screen context
wglMakeCurrent(ghDC, ghRC);
wglShareLists(ghRC, RTT.wgl.hGlRc);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE);
glClear(GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, ClientWidth, ClientHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
wglMakeCurrent(RTT.wgl.hdc, RTT.wgl.hGlRc);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, RTT.texture);
PaintGL();
glDisable(GL_TEXTURE_2D);
wglMakeCurrent(ghDC, ghRC);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, RTT.texture);
RTT.wgl.wglBindTexImageARB(RTT.wgl.hBuffer, WGL_FRONT_LEFT_ARB);
glBegin(GL_QUADS);
glColor4ub(255,255,255,255);
glTexCoord2f (0.0, 0.0); glVertex2f (-1.0, -1.0);
glTexCoord2f (1.0, 0.0); glVertex2f (1.0, -1.0);
glTexCoord2f (1.0, 1.0); glVertex2f (1.0, 1.0);
glTexCoord2f (0.0, 1.0); glVertex2f (-1.0, 1.0);
glEnd();
RTT.wgl.wglReleaseTexImageARB(RTT.wgl.hBuffer, WGL_FRONT_LEFT_ARB);
glDisable(GL_TEXTURE_2D);
glFlush();
SwapBuffers(ghDC);
wglMakeCurrent(NULL,NULL);
}
这是我的第二个 GLForm 的 DrawScene ：问题是我只看到彩色四边形，但这个四边形没有纹理，或者纹理是空的：
void TGLForm2::DrawSceneForm2()
{
wglMakeCurrent(ghDC2, ghRC2);
ClientWidth = 1920;
ClientHeight = 1080;
wglShareLists(RTT.wgl.hGlRc, ghRC2);
if (wglShareLists(RTT.wgl.hGlRc,ghRC2) == FALSE)
SCmsgError(AnsiString().sprintf("wglShareLists returned %i", GetLastError()));
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE); //ARC
glClear(GL_DEPTH_BUFFER_BIT);
glViewport(0, 0, ClientWidth, ClientHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, RTT.texture);
RTT.wgl.wglBindTexImageARB(RTT.wgl.hBuffer, WGL_FRONT_LEFT_ARB);
glBegin(GL_QUADS);
glColor4ub(200,200,200,200);
glTexCoord2f (0.0, 0.0); glVertex2f (-1.0, -1.0);
glTexCoord2f (1.0, 0.0); glVertex2f (1.0, -1.0);
glTexCoord2f (1.0, 1.0); glVertex2f (1.0, 1.0);
glTexCoord2f (0.0, 1.0); glVertex2f (-1.0, 1.0);
glEnd();
RTT.wgl.wglReleaseTexImageARB(RTT.wgl.hBuffer, WGL_FRONT_LEFT_ARB);
glDisable(GL_TEXTURE_2D);
glFlush();
SwapBuffers(ghDC);
}
=> 我如何检查该纹理是否为空？
将其导出为位图并检查它？
=> DrawSceneForm2 中的 wglShareLists 返回 GetLastError 错误：
错误 6：ERROR_INVALID_HANDLE 句柄无效。
=> 有人看到这个 wglShareList 或我的代码有什么问题吗？
