QSurfaceFormat qglx_reduceSurfaceFormat(const QSurfaceFormat &format, bool *reduced)
{
QSurfaceFormat retFormat = format;
*reduced = true;
if (retFormat.redBufferSize() > 1) {
retFormat.setRedBufferSize(1);
} else if (retFormat.greenBufferSize() > 1) {
retFormat.setGreenBufferSize(1);
} else if (retFormat.blueBufferSize() > 1) {
retFormat.setBlueBufferSize(1);
} else if (retFormat.samples() > 1) {
retFormat.setSamples(qMin(retFormat.samples() / 2, 16));
} else if (retFormat.stereo()) {
retFormat.setStereo(false);
}else if (retFormat.stencilBufferSize() > 0) {
retFormat.setStencilBufferSize(0);
}else if (retFormat.hasAlpha()) {
retFormat.setAlphaBufferSize(0);
}else if (retFormat.depthBufferSize() > 0) {
retFormat.setDepthBufferSize(0);
}else if (retFormat.swapBehavior() != QSurfaceFormat::SingleBuffer) {
retFormat.setSwapBehavior(QSurfaceFormat::SingleBuffer);
}else{
*reduced = false;
}
return retFormat;
}
GLXFBConfig qglx_findConfig(Display *display, int screen , const QSurfaceFormat &format, int drawableBit)
{
bool reduced = true;
GLXFBConfig chosenConfig = 0;
QSurfaceFormat reducedFormat = format;
while (!chosenConfig && reduced) {
QVector<int> spec = qglx_buildSpec(reducedFormat, drawableBit);
int confcount = 0;
GLXFBConfig *configs;
configs = glXChooseFBConfig(display, screen,spec.constData(),&confcount);
if (confcount)
{
for (int i = 0; i < confcount; i++) {
chosenConfig = configs[i];
// Make sure we try to get an ARGB visual if the format asked for an alpha:
if (reducedFormat.hasAlpha()) {
int alphaSize;
glXGetFBConfigAttrib(display,configs[i],GLX_ALPHA_SIZE,&alphaSize);
if (alphaSize > 0) {
XVisualInfo *visual = glXGetVisualFromFBConfig(display, chosenConfig);
bool hasAlpha = false;
#if !defined(QT_NO_XRENDER)
XRenderPictFormat *pictFormat = XRenderFindVisualFormat(display, visual->visual);
hasAlpha = pictFormat->direct.alphaMask > 0;
#else
hasAlpha = visual->depth == 32;
#endif
XFree(visual);
if (hasAlpha)
break;
}
} else {
break; // Just choose the first in the list if there's no alpha requested
}
}
XFree(configs);
}
if (!chosenConfig)
reducedFormat = qglx_reduceSurfaceFormat(reducedFormat,&reduced);
}
return chosenConfig;
}
QVector<int> qglx_buildSpec(const QSurfaceFormat &format, int drawableBit)
{
QVector<int> spec(48);
int i = 0;
spec[i++] = GLX_LEVEL;
spec[i++] = 0;
spec[i++] = GLX_DRAWABLE_TYPE; spec[i++] = drawableBit;
spec[i++] = GLX_RENDER_TYPE; spec[i++] = GLX_RGBA_BIT;
spec[i++] = GLX_RED_SIZE; spec[i++] = (format.redBufferSize() == -1) ? 1 : format.redBufferSize();
spec[i++] = GLX_GREEN_SIZE; spec[i++] = (format.greenBufferSize() == -1) ? 1 : format.greenBufferSize();
spec[i++] = GLX_BLUE_SIZE; spec[i++] = (format.blueBufferSize() == -1) ? 1 : format.blueBufferSize();
if (format.hasAlpha()) {
spec[i++] = GLX_ALPHA_SIZE; spec[i++] = format.alphaBufferSize();
}
spec[i++] = GLX_DOUBLEBUFFER; spec[i++] = format.swapBehavior() != QSurfaceFormat::SingleBuffer ? True : False;
spec[i++] = GLX_STEREO; spec[i++] = format.stereo() ? True : False;
if (format.depthBufferSize() > 0) {
spec[i++] = GLX_DEPTH_SIZE; spec[i++] = format.depthBufferSize();
}
if (format.stencilBufferSize() > 0) {
spec[i++] = GLX_STENCIL_SIZE; spec[i++] = (format.stencilBufferSize() == -1) ? 1 : format.stencilBufferSize();
}
if (format.samples() > 1) {
spec[i++] = GLX_SAMPLE_BUFFERS_ARB;
spec[i++] = 1;
spec[i++] = GLX_SAMPLES_ARB;
spec[i++] = format.samples();
}
spec[i++] = XNone;
return spec;
}
GLXFBConfig qglx_findConfig(Display *display, int screen , const QSurfaceFormat &format, int drawableBit)
{
// Allow forcing LIBGL_ALWAYS_SOFTWARE for Qt 5 applications only.
// This is most useful with drivers that only support OpenGL 1.
// We need OpenGL 2, but the user probably doesn't want
// LIBGL_ALWAYS_SOFTWARE in OpenGL 1 apps.
static bool checkedForceSoftwareOpenGL = false;
static bool forceSoftwareOpenGL = false;
if (!checkedForceSoftwareOpenGL) {
// If LIBGL_ALWAYS_SOFTWARE is already set, don't mess with it.
// We want to unset LIBGL_ALWAYS_SOFTWARE at the end so it does not
// get inherited by other processes, of course only if it wasn't
// already set before.
if (!qEnvironmentVariableIsEmpty("QT_XCB_FORCE_SOFTWARE_OPENGL")
&& !qEnvironmentVariableIsSet("LIBGL_ALWAYS_SOFTWARE"))
forceSoftwareOpenGL = true;
checkedForceSoftwareOpenGL = true;
}
if (forceSoftwareOpenGL)
qputenv("LIBGL_ALWAYS_SOFTWARE", QByteArrayLiteral("1"));
bool reduced = true;
GLXFBConfig chosenConfig = 0;
QSurfaceFormat reducedFormat = format;
while (!chosenConfig && reduced) {
QVector<int> spec = qglx_buildSpec(reducedFormat, drawableBit);
int confcount = 0;
GLXFBConfig *configs;
configs = glXChooseFBConfig(display, screen,spec.constData(),&confcount);
if (confcount)
{
for (int i = 0; i < confcount; i++) {
chosenConfig = configs[i];
// Make sure we try to get an ARGB visual if the format asked for an alpha:
if (reducedFormat.hasAlpha()) {
int alphaSize;
glXGetFBConfigAttrib(display,configs[i],GLX_ALPHA_SIZE,&alphaSize);
if (alphaSize > 0) {
XVisualInfo *visual = glXGetVisualFromFBConfig(display, chosenConfig);
bool hasAlpha = false;
#if !defined(QT_NO_XRENDER)
XRenderPictFormat *pictFormat = XRenderFindVisualFormat(display, visual->visual);
hasAlpha = pictFormat->direct.alphaMask > 0;
#else
hasAlpha = visual->depth == 32;
#endif
XFree(visual);
if (hasAlpha)
break;
}
} else {
break; // Just choose the first in the list if there's no alpha requested
}
}
XFree(configs);
}
if (!chosenConfig)
reducedFormat = qglx_reduceSurfaceFormat(reducedFormat,&reduced);
}
// unset LIBGL_ALWAYS_SOFTWARE now so other processes don't inherit it
if (forceSoftwareOpenGL)
qunsetenv("LIBGL_ALWAYS_SOFTWARE");
return chosenConfig;
}
