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我尝试在两个类之间共享一个 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 管理）

我的目标是在两个 openGL 窗口中显示相同的缓冲区。

所以我在第一个表单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;

我对其进行初始化，使其具有与第一个 GLForm 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()”绘图完美地绘制在此表单上：

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 QUAD 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);
}

=> 我如何检查这个纹理是否为空？

将其导出到位图并检查它？

=> DrawSceneForm2 中的 wglShareLists 使用 GetLastError 返回错误：

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？

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2 回答 2

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调用wglShareLists时，上下文不能是当前的。最好先分享，然后再做任何其他事情。共享上下文将共享此后创建的任何内容。最好的办法是创建所有需要在启动时共享的上下文。如果您使用 WGL_ARB_create_context，那么您甚至可以在创建调用中自动执行此操作。

如果由于某种原因不能（但是，为什么？），那么wglMakeCurrent(0,0);首先（你在代码中做相反的事情，你在共享之前使上下文成为当前的）。

于 2011-04-19T18:34:36.693 回答
1

我有一个类似的问题：

wglShareLists 返回 0

GetLastError() 返回 3221684311 (0xc0070057)

事实证明，在调用 wglShareLists 之前，您无法对 hglrc2（传递给 wglShareLists 的第二个参数）做太多事情。在我的情况下，我创建了 glUseProgram 一个着色器，然后尝试了 wglShareLists 导致上面显示的错误。在第二个 RC 的 wglCreateContext(hDC) 工作后立即将 wglShareLists 移动到。我能够在 2 个上下文中共享纹理。

于 2016-05-16T15:02:18.057 回答