我正在使用一些用于科学可视化的 OpenGL 代码，但我在让其橡皮筋在较新的硬件上工作时遇到了问题。该代码在现有场景上绘制一个“缩放窗口”，其中“缩放窗口”的一个角在存储的左键单击位置，另一个在鼠标移动时位于鼠标下方。在第二个左键单击场景放大到选定的窗口。
当鼠标在场景中移动时，我看到的症状是：
- 出现的橡皮筋伪影是用于创建“缩放窗口”的行，没有被第二个“RenderLogic”传递从缓冲区中删除（参见下面的代码）
- 我可以清楚地看到前一个缓冲区的内容在交换缓冲区时闪烁并消失
上述问题不会发生在低端硬件上，例如我拥有的上网本上的集成显卡。另外，我不记得大约 5 年前编写此代码时的这个问题。
以下是相关的代码部分，经过精简以专注于相关的 OpenGL：
// Called by every mouse move event
// Makes use of current device context (m_hDC) and rendering context (m_hRC)
void MyViewClass::DrawLogic()
{
BOOL bSwapRv = FALSE;
// Make the rendering context current
if (!wglMakeCurrent(m_hDC, m_hRC))
// ... error handling
// Perform the logic rendering
glLogicOp(GL_XOR);
glEnable(GL_COLOR_LOGIC_OP);
// Draws the rectangle on the buffer using XOR op
RenderLogic();
bSwapRv = ::SwapBuffers(m_hDC);
// Removes the rectangle from the buffer via a second pass
RenderLogic();
glDisable(GL_COLOR_LOGIC_OP);
// Release the rendering context
if (!wglMakeCurrent(NULL, NULL))
// ... error handling
}
void MyViewClass::RenderLogic(void)
{
glLineWidth(1.0f);
glColor3f(0.6f,0.6f,0.6f);
glEnable(GL_LINE_STIPPLE);
glLineStipple(1, 0x0F0F);
glBegin(GL_LINE_LOOP);
// Uses custom "Point" class with Coords() method returning double*
// Draw rectangle with corners at clicked location and current location
glVertex2dv(m_pntClickLoc.Coords());
glVertex2d(m_pntCurrLoc.X(), m_pntClickLoc.Y());
glVertex2dv(m_pntCurrLoc.Coords());
glVertex2d(m_pntClickLoc.X(), m_pntCurrLoc.Y());
glEnd();
glDisable(GL_LINE_STIPPLE);
}
// Setup code that might be relevant to the buffer configuration
bool MyViewClass::SetupPixelFormat()
{
PIXELFORMATDESCRIPTOR pfd = {
sizeof(PIXELFORMATDESCRIPTOR),
1, // Version number (?)
PFD_DRAW_TO_WINDOW // Format must support window
| PFD_SUPPORT_OPENGL // Format must support OpenGL
| PFD_DOUBLEBUFFER, // Must support double buffering
PFD_TYPE_RGBA, // Request an RGBA format
32, // Select a 32 bit colour depth
0, 0, 0, 0, 0, 0, // Colour bits ignored (?)
8, // Alpha buffer bits
0, // Shift bit ignored (?)
0, // No accumulation buffer
0, 0, 0, 0, // Accumulation bits ignored
16, // 16 bit Z-buffer
0, // No stencil buffer
0, // No accumulation buffer (?)
PFD_MAIN_PLANE, // Main drawing layer
0, // Number of overlay and underlay planes
0, 0, 0 // Layer masks ignored (?)
};
PIXELFORMATDESCRIPTOR chosen_pfd;
memset(&chosen_pfd, 0, sizeof(PIXELFORMATDESCRIPTOR));
chosen_pfd.nSize = sizeof(PIXELFORMATDESCRIPTOR);
// Find the closest match to the pixel format
m_uPixelFormat = ::ChoosePixelFormat(m_hDC, &pfd);
// Make sure a pixel format could be found
if (!m_uPixelFormat)
return false;
::DescribePixelFormat(m_hDC, m_uPixelFormat, sizeof(PIXELFORMATDESCRIPTOR), &chosen_pfd);
// Set the pixel format for the view
::SetPixelFormat(m_hDC, m_uPixelFormat, &chosen_pfd);
return true;
}
任何有关如何删除人工制品的指示将不胜感激。
@Krom - 下图
