Stereo Rendering Demo

James W. Walker — Tue, 24 Feb 2009 07:02:28 -0000

The new stereo demo implements several methods of 3D rendering such as red/cyan anaglyphs. It shows the use of view plane cameras and mixing OpenGL calls with Quesa. The user interface is Mac only, but the techniques are applicable to Windows as well.

Line Width Style Objects

James W. Walker — Sat, 10 May 2008 23:40:18 -0000

The OpenGL renderer now supports a new kind of style object to set the width in pixels of geometries such as lines and edge-filled meshes.

Rendering Features Page added to Wiki

James W. Walker — Mon, 28 Apr 2008 01:49:14 -0000

Quesa's wiki has a new page describing several advanced rendering techniques: Shadows, per-pixel lighting, and full-screen antialiasing. See: http://quesa.wiki.sourceforge.net/OpenGL+Rendering+Effects

Quesa 2.0 Release

James W. Walker — Sat, 26 Jan 2008 23:19:20 -0000

The Quesa 3D graphics engine has been updated to version 2.0. This update introduces a new OpenGL renderer that supports shadows and per-pixel lighting. Other changes include improved 3DS file format support and improved Mac Cocoa support.

Source and binary packages for Mac OS X and Windows are available for download. Source is also available by CVS.

Shadow rendering available

James W. Walker — Thu, 07 Jun 2007 23:06:44 -0000

The Quesa OpenGL renderer now has an option to render shadows. It produces sharp-edged shadows from any directional, spot, or point light that has its cast-shadows flag set to kQ3True. It respects the casts-shadows style but not the receive-shadows style. Translucent objects do not cast shadows, nor do lines or points.

Rendering with shadows can be requested by setting an object property on the renderer object:

TQ3Boolean theFlag = kQ3True; Q3Object_SetProperty( theRenderer, kQ3RendererPropertyShadows, sizeof(theFlag), &theFlag );

This option can be used with or without the per-pixel lighting option.

Hardware Requirements

In order to render with shadows, your OpenGL drawing context must:

1. Be able to have a stencil buffer at least 8 bits deep, as well as a depth buffer. (This is usually not a problem. One case where it fails is the Windows software renderer.)

2. Support either OpenGL 2.0 or the GL_EXT_stencil_two_side extension.

It is preferable, but not essential, to have the extensions GL_EXT_stencil_wrap and GL_NV_depth_clamp as well.

Warnings

For angle aspect cameras, the algorithm sets the "yon" value of your camera range to infinity. To prevent surprises, it would be a good idea to set "yon" to infinity yourself. While it is true that you get the best depth resolution when hither is as large as possible and yon is as small as possible, it is much more important to make hither as large as possible.

If you are using Quesa on Windows, beware that Windows does not allow setting the pixel format of a window more than once. This means that if you start rendering without shadows, and then attempt to turn on shadows, it will fail, because you will not be able to get a stencil buffer. You can work around this problem by explicitly requesting a stencil buffer from the start, using kQ3DrawContextPropertyGLStencilBufferDepth.

Performance

Shadows require a multi-pass rendering algorithm. The first pass handles ambient light and non-shadow-casting lights, assuming there are no more than 8 of them. Then for each shadow-casting light, there is a stencil marking pass followed by a lighting pass. Naturally, this will be slower than a single-pass algorithm. There is even more of a speed hit if you combine per-pixel lighting with shadows, since each lighting pass will be slower.

Naturally, you can improve performance by designating some lights and some objects as not casting shadows. It also helps to use the Remove backfacing style when feasible, and to ensure that your TriMeshes supply face normal vectors.

During shadow lighting passes, the renderer culls meshes that are outside the light cone of a spot light or beyond the reach of a point or spot light.

Per-Pixel Lighting Available

James W. Walker — Fri, 13 Apr 2007 00:25:32 -0000

The Quesa OpenGL renderer now has an option to perform per-pixel lighting if the video card supports OpenGL Shading Language. We have posted a screenshot showing the difference between per-pixel and the usual per-vertex lighting.

New OpenGL renderer added

James W. Walker — Sun, 11 Feb 2007 04:58:00 -0000

A new renderer has been added to Quesa, which aims to acheive better speed by taking advantage of OpenGL features such as vertex buffer objects.

Visible Differences from Interactive Renderer

* There is no distinction between the "both" and "flip" backfacing
styles. Both cases use normal OpenGL two-sided lighting.

* Geometries of dimension less than 2 (Point, Line, PolyLine,
Ellipse, NURBCurve) are unaffected by the direction of the light.

* Textures of pixel type kQ3PixelTypeARGB16 are treated differently.
With the default linear texture filtering, you will see a smooth
transition from transparent to opaque.

Performance Notes

* In order for a TriMesh to be on the "fast path" for the OpenGL
renderer,

* it must be a retained object
* it must have vertex normals
* it must not have color or texture with transparency
* it must not have per-face colors (unless per-vertex colors are also
present)
* it must not have per-face textures

* Per-face normals on TriMeshes are ignored.

* If a TriMesh falls off the fast path due to lack of vertex normals,
or due to having per-face color and not per-vertex color, then the
renderer will call Q3TriMesh_Optimize and cache the result. This
takes a little extra time when the object is first rendered, but
should be fast thereafter.

* You will get better performance with a few large TriMeshes than
with many small ones. The "MultiBox" test in the Geom Test sample
is a particularly bad case, having 4000 TriMeshes with 2 triangles
each.

* A fast-path TriMesh with more than 500 faces will be cached as a
vertex buffer object when the hardware supports it, and otherwise
as a display list.

* When a fast-path TriMesh has more than 500 faces, we compute a
triangle strip for it and cache the strip in an object property.

* This renderer gives much more of a performance boost when the video
card has actual VRAM rather than shared system memory.

HIQuesaView sample code added

James W. Walker — Mon, 29 Jan 2007 01:51:41 -0000

A new sample program for Mac OS X has been added to the Quesa project. This sample illustrates how to use a Quesa view as a custom control is a compositing-mode Carbon window. It is available by CVS.

VRML Reader plug-in updated to 1.0.4

James W. Walker — Tue, 07 Nov 2006 01:42:09 -0000

The VRML Reader plug-in for Quesa has been updated to version 1.0.4. This release handles Anchor nodes as if they were Groups, and is less likely to get confused by PROTO declarations.

The source is available by CVS, and a package of binaries for Mac and Windows has been posted under Files.

Quesa is a cross-platform 3D scene graph and rendering engine.

Quesa 1.8 Released

James W. Walker — Tue, 25 Apr 2006 00:21:58 -0000

The Quesa 3D graphics engine has been updated to version 1.8. This update introduces a cartoon-style renderer and a VRML file format reader plug-in, makes the code compatible with Intel Macs and 64-bit platforms, and includes various other improvements and bug fixes.

Source and binary packages for Mac, Windows, and Unix are available under Files. Source is also available by CVS, although SourceForge has CVS problems at this writing.

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