using Overlay planes with the GlxMDraw Widget

Thread View: comp.sys.sgi.graphics

2 messages

[T] Back to Threads [V] Tree View [G] Group Articles

2 total messages Started by Matthew E. Moses Sat, 23 Jan 1993 23:22

#122

Author: Matthew E. Moses
Date: Sat, 23 Jan 1993 23:22

57 lines
2856 bytes

I am using the GL Widget in combination with motif.  I want to use the 
overlay plane for rubber-banding.  I've looked at the sample overlay.c from 
the 4Dgifts examples but it doesn't provide any insight.  I draw an image in 
the normal plane and then based on mouse input use the following code to do the rubber banding from an input callback:

	  XtVaGetValues(w, GlxNoverlayWindow, &over, NULL);

	  err = GLXwinset(XtDisplay(w), over);
	  fprintf(stdout, "\n overlay window: %d, err: %d", over, err); 
	  fflush(stdout);

	  c3i(Black); /* erase old band */
	  rect(oldX, oldY, oldX1, oldY1);

	  c3i(Blue); /* draw new band */
	  rect(mouseDownX, mouseDownY, newX, newY);
	  
	  gflush();

The GLXwinset call is returning 0 (no error) but the drawing rect call doesn't show up in the overlay plane.

Does anyone know if there is a special way you have to initialize the overlay planes of the widget?  The following is how I am initializing the widget:

static GLXconfig glxConfig [] = 
{
    { GLX_NORMAL, GLX_RGB, TRUE },
    { GLX_OVERLAY,  GLX_BUFSIZE, 2},
    { GLX_OVERLAY, GLX_RGB, TRUE },
    { 0, 0, 0 }
};

...

     XtSetArg(args[i], GlxNglxConfig, glxConfig); i++;
     XtSetArg(args[i], GlxNuseOverlay, True); i++;
     gGLWidget = XtCreateManagedWidget("glwidget", glxMDrawWidgetClass,
				       frame, args, i);
     XtAddCallback(gGLWidget, GlxNoverlayExposeCallback, OverlayDrawSceneCB, 
		   (XtPointer) NULL);
     XtAddCallback(gGLWidget, GlxNinputCallback, HandleInputCB, 
		   (XtPointer) NULL);
     XtAddCallback(gGLWidget, GlxNexposeCallback, DrawSceneCB, 
		   (XtPointer) NULL);
     XtAddCallback(gGLWidget, GlxNresizeCallback, ResizeScreenCB, 
		   (XtPointer) NULL);
     XtAddCallback(gGLWidget, GlxNginitCallback, InitializeGLCB, 
		   (XtPointer) NULL);

Any help or pointers to information would be appreciated.


*------------------*-----------------------*-----------------------------*
* Matthew E. Moses * AHPCRC Systems Staff  * moses@ahpcrc.umn.edu        *
*                  * CIS Consultant        * moses@mermaid.micro.umn.edu *
*  U of Minnesota  *-----------------------*-----------------------------*   
*                  * Office: (612)626-8136 * Home: (612)624-0126         *
*------------------*-----------------------*-----------------------------*

Re: using Overlay planes with the GlxMDraw Widget

#125

Author: Joel Tesler
Date: Mon, 25 Jan 1993 17:40

26 lines
1522 bytes

In article <C1By8u.JFv@news2.cis.umn.edu>, moses@i5.arc.umn.edu writes:
> I am using the GL Widget in combination with motif.  I want to use the 
> overlay plane for rubber-banding.  

A couple of things:

First, are you installing the colormaps?  You need to use
XSetWMColormapWindows to install the colormaps of both the normal and
overlay GL colormaps.  If they aren't installed, you won't get the
correct colors.

Second, and this is probably the problem, you are trying to use RGB
for the overlay planes.  Some of our very high end hardware may
support this (I don't know for sure), but most of the hardware
doesn't; and none of it does with overlays with a depth of 2.  With a
depth of 2 you have exactly 3 colors + transparent; and the best way
to allocate those three colors is to use X color allocation
mechanisms (It is often a good idea to get a new X colormap for the
overlay planes so you don't need to share the 3 colors between
multiple applications).  Then use color (not c3i) to allocate the colors.

Joel Tesler
joel@sgi.com
415-390-3048

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads