func (window *Win32Window) GetHDC() unsafe.Pointer {
if window.hdc != nil {
return unsafe.Pointer(&window.hdc)
}
window.hdc = C.GetDC(window.hwnd)
px := C.PIXELFORMATDESCRIPTOR{
dwFlags: 0x00000001 | 0x00000020 | 0x00000004,
iPixelType: 0,
cColorBits: 32,
cDepthBits: 32,
iLayerType: 0,
}
px.nSize = (C.WORD)(unsafe.Sizeof(px))
pxFormat := C.ChoosePX(window.hdc, &px)
if pxFormat == 0 {
return nil
}
res := C.SetPixelFormat(window.hdc, pxFormat, &px)
if res == 0 {
return nil
}
return unsafe.Pointer(&window.hdc)
}
func (ic *contextInternal) initializeFromSettings(settings ContextSettings, width, height int) ThreadError {
ic.deactivateSignal = make(chan bool)
ic.settings = settings
ic.window = createHiddenWindow(width, height)
if ic.window == nil {
// C.GetLastError()
return NewThreadError(fmt.Errorf("could not create window (%d)", C.GetLastError()), true)
}
ic.ownsWindow = true
ic.hdc = C.GetDC(ic.window)
if ic.hdc == nil {
return NewThreadError(errors.New("no device context"), true)
}
if sharedContext == nil { // if there is no shared context, we are it
ic.isSharedContext = true
pfd := C.PIXELFORMATDESCRIPTOR{
nSize: C.PIXELFORMATDESCRIPTOR_size, // size of this pfd
nVersion: 1, // version number
iPixelType: C.PFD_TYPE_RGBA, // RGBA type
cColorBits: 24, // 24-bit color depth
cDepthBits: 32, // 32-bit z-buffer
iLayerType: C.PFD_MAIN_PLANE, // main layer
// support window | OpenGL | double buffer
dwFlags: C.PFD_DRAW_TO_WINDOW | C.PFD_SUPPORT_OPENGL | C.PFD_DOUBLEBUFFER,
}
// get the best available match of pixel format for the device context
// make that the pixel format of the device context
if iPixelFormat := C.ChoosePixelFormat(ic.hdc, &pfd); iPixelFormat == 0 {
return NewThreadError(fmt.Errorf("sharedContext: ChoosePixelFormat failed (%d)", C.GetLastError()), true)
} else if C.SetPixelFormat(ic.hdc, iPixelFormat, &pfd) == C.FALSE {
return NewThreadError(fmt.Errorf("sharedContext: SetPixelFormat failed (%d)", C.GetLastError()), true)
}
ic.context = C.wglCreateContext(ic.hdc)
if ic.context == nil {
return NewThreadError(fmt.Errorf("sharedContext: wglCreateContext failed (%d)", C.GetLastError()), true)
}
} else { // otherwise we push the commands onto the shared context thread
bitsPerPixel := GetDefaultMonitor().GetDesktopMode().BitsPerPixel
ic.context = createContext(&sharedContext.internal.procs, sharedContext.internal.context, ic.hdc, bitsPerPixel, &ic.settings)
if ic.context == nil {
return NewThreadError(fmt.Errorf("could not create context (%d)", C.GetLastError()), true)
}
}
// signal because we start out deactivated
ic.signalDeactivation()
return nil
}
func createContext(procs *C.wglProcs, sharedContext C.HGLRC, hdc C.HDC, bitsPerPixel uint, settings *ContextSettings) C.HGLRC {
bestFormat := BestwglChoosePixelFormatARB(procs, hdc, bitsPerPixel, settings)
if bestFormat == 0 {
bestFormat = BestChoosePixelFormat(hdc, bitsPerPixel, settings)
}
if bestFormat == 0 {
return nil // Failed to find a suitable pixel format for device context -- cannot create OpenGL context
}
// Extract the depth and stencil bits from the chosen format
actualFormat := C.PIXELFORMATDESCRIPTOR{
nSize: C.PIXELFORMATDESCRIPTOR_size,
nVersion: 1,
}
if C.__DescribePixelFormat(hdc, bestFormat, C.PIXELFORMATDESCRIPTOR_size, &actualFormat) == 0 {
return nil
}
settings.DepthBits = uint(actualFormat.cDepthBits)
settings.StencilBits = uint(actualFormat.cStencilBits)
// Set the chosen pixel format
if C.SetPixelFormat(hdc, bestFormat, &actualFormat) == C.FALSE {
return nil // Failed to set pixel format for device context -- cannot create OpenGL context
}
if procs.p_wglCreateContextAttribsARB != nil {
for settings.MajorVersion >= 3 {
attributes := [...]C.int{
C.WGL_CONTEXT_MAJOR_VERSION_ARB, C.int(settings.MajorVersion),
C.WGL_CONTEXT_MINOR_VERSION_ARB, C.int(settings.MinorVersion),
C.WGL_CONTEXT_PROFILE_MASK_ARB, C.WGL_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
0, 0,
}
if context := C.__wglCreateContextAttribsARB(procs, hdc, sharedContext, &attributes[0]); context != nil {
return context
}
// If we couldn't create the context, lower the version number and try again -- stop at 3.0
// Invalid version numbers will be generated by this algorithm (like 3.9), but we really don't care
if settings.MinorVersion > 0 {
// If the minor version is not 0, we decrease it and try again
settings.MinorVersion--
} else {
// If the minor version is 0, we decrease the major version
settings.MajorVersion--
settings.MinorVersion = 9
}
}
}
// set the context version to 2.0 (arbitrary)
settings.MajorVersion = 2
settings.MinorVersion = 0
context := C.wglCreateContext(hdc)
if context == nil {
return nil // Failed to create an OpenGL context for this window
}
// Share this context with others
C.wglShareLists(sharedContext, context)
return context
}