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[FLEXPLAN3D]

This question is probably for Silverfrost Developers.

The clearwin support for Opengl has not kept pace with the more recent extensions to the Opengl API.

In particular the number of wgl function prototypes in the WINGDI.H are now very limited.

One feature that I would like to make use of, which pretty well all graphic cards support, is multi-sampling which is an anti-aliasing feature which smooths jagged lines. This requires the setting up of a multisampled frame buffer.

The Opengl documentation shows that this can be set up with the appropriate wgl function calls or more simply using the GLUT library to initialise the display.

Neither of these options seem to currently available with the Silverfrost compilers.

Is there any way that multi-sampling can be implemented at present ?

Ideally an extra argument to the %og statement would be useful

eg. %^og[stencil,double,depth32,multisample4]

[DanRRight]

You don't have glut32.dll ?

[PaulLaidler]

FLEXPLAN3D

Could you provide links to the functions that you want to use?

If they are not already in opengl.ins then it should be a simple matter to add them.

Providing support via the %gl options may be possible. Again some illustrative C code would help.

[FLEXPLAN3D]

This code to set multisampling is taken from Opengl Superbible by R wright. I cannot get it to compile with SCC compiler.

I think if this worked I could access the multi-sampling I require.

As you can see it needs quite a few extra wgl functions.

#include <windows.h>
//extract from GLTools.h
int gltIsWGLExtSupported(HDC hDC, const char *szExtension);

// extract from WGLEXT.h
extern BOOL WINAPI wglGetPixelFormatAttribivARB (HDC, int, int, UINT, const int *, int *);
extern BOOL WINAPI wglChoosePixelFormatARB (HDC, const int *, const FLOAT *, UINT, int *, UINT *);
typedef BOOL (WINAPI * PFNWGLGETPIXELFORMATATTRIBIVARBPROC) (HDC hdc, int iPixelFormat, int iLayerPlane, UINT nAttributes, const int *piAttributes, int *piValues);



// Find the best available pixelformat, including if Multisample is available
void FindBestPF(HDC hDC, int *nRegularFormat, int *nMSFormat);


///////////////////////////////////////////////////////////////////////////////
// Select pixelformat with desired attributes
// Returns the best available "regular" pixel format, and the best available
// Multisampled pixelformat (0 if not available)
void FindBestPF(HDC hDC, int *nRegularFormat, int *nMSFormat)
{
*nRegularFormat = 0;
*nMSFormat = 0;

// easy check, just look for the entrypoint
if(gltIsWGLExtSupported(hDC, "WGL_ARB_pixel_format"))
if(wglGetPixelFormatAttribivARB == NULL)
wglGetPixelFormatAttribivARB = (PFNWGLGETPIXELFORMATATTRIBIVARBPROC)
wglGetProcAddress("wglGetPixelFormatAttribivARB");

// First try to use new extended wgl way
if(wglGetPixelFormatAttribivARB != NULL)
{
// Only care about these attributes
int nBestMS = 0;
int i;
int iResults[9];
int iAttributes [9] = { WGL_SUPPORT_OPENGL_ARB, // 0
WGL_ACCELERATION_ARB, // 1
WGL_DRAW_TO_WINDOW_ARB, // 2
WGL_DOUBLE_BUFFER_ARB, // 3
WGL_PIXEL_TYPE_ARB, // 4
WGL_DEPTH_BITS_ARB, // 5
WGL_STENCIL_BITS_ARB, // 6
WGL_SAMPLE_BUFFERS_ARB, // 7
WGL_SAMPLES_ARB }; // 8

// How many pixelformats are there?
int nFormatCount[] = { 0 };
int attrib[] = { WGL_NUMBER_PIXEL_FORMATS_ARB };
wglGetPixelFormatAttribivARB(hDC, 1, 0, 1, attrib, nFormatCount);

// Loop through all the formats and look at each one
for(i = 0; i < nFormatCount[0]; i++)
{
// Query pixel format
wglGetPixelFormatAttribivARB(hDC, i+1, 0, 9, iAttributes, iResults);

// Match? Must support OpenGL AND be Accelerated AND draw to Window
if(iResults[0] == 1 && iResults[1] == WGL_FULL_ACCELERATION_ARB && iResults[2] == 1)
if(iResults[3] == 1) // Double buffered
if(iResults[4] == WGL_TYPE_RGBA_ARB) // Full Color
if(iResults[5] >= 16) // Any Depth greater than 16
if(iResults[6] > 0) // Any Stencil depth (not zero)
{
// We have a candidate, look for most samples if multisampled
if(iResults[7] == 1) // Multisampled
{
if(iResults[8] > nBestMS) // Look for most samples
{
*nMSFormat = i; // Multisamples
nBestMS = iResults[8]; // Looking for the best
}
}
else // Not multisampled
{
// Good enough for "regular". This will fall through
*nRegularFormat = i

[PaulLaidler]

FLEXPLAN3D

Your post may have been truncated. If it is very large then you could use something like DropBox.

[FLEXPLAN3D]

Paul

My apologies - here is the missing bit.

I can send a file if you wish, but I don't have a contact e-mail for you.

Thanks

Bob

}
}
}
}
else
{
// Old fashioned way...
// or multisample
PIXELFORMATDESCRIPTOR pfd = {
sizeof(PIXELFORMATDESCRIPTOR),
1,
PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,
PFD_TYPE_RGBA, // Full color
32, // Color depth
0,0,0,0,0,0,0, // Ignored
0,0,0,0, // Accumulation buffer
24, // Depth bits
8, // Stencil bits
0,0,0,0,0,0 }; // Some used, some not

*nRegularFormat = ChoosePixelFormat(hDC, &pfd);
}
}

[PaulLaidler]

Bob

I have had a look at your code.

I can get it to compile by downloading wglext.h from the Internet and by commenting out the call to wglGetProcAddress (which would not be needed if the relevant DLL is available at link time).

Sorry but I don't see any way to progress from this point.

[FLEXPLAN3D]

Paul

Thanks for looking at it - if you can think of any other way of implemented multi-sampling I would still be interested.

Bob