Hello, I found some things to improve the quality of the shadow mapping, and written in more comments.
http://rene.f0o.com/~rene/stuff/shadows_rd.zip It also by default uses a polygon as a floor, and a teapot from GLUT. There's a constant at the top of demoShadows.py which changes this. However the objects you draw are a very simple part of this demo, they could be anything really. The complexity comes from the other code. I think maybe the glPolygonOffset call may have something to do with it... but haven't managed to get the call to do anything. I tried glScale, and glTranslate, but that seems to be wrong - and in one paper it says you can't use translate/scale but have to use glPolygonOffset. The main thing which improved quality for me was to use GL_DEPTH_COMPONENT32 instead of GL_DEPTH_COMPONENT with the glTexImage2D call. GL_DEPTH_COMPONENT lets the driver pick the resolution (which for this Imac as only 8 bit). I haven't managed to increase the resolution of the shadow map successfully. Apparently it's possible to do shadow mapping in one pass... but it's more complicated. However I think using display lists will be quite quick even though it's done in 3 passes. eg. # 1. draw stuff first time, and create display list at the same time. # 2. second pass reusing display list. # 3. third pass reusing display list. Another improvement would be to anti-alias the shadows some how. There's a whole bunch of different methods for doing this mentioned in the literature, but I haven't tried anything yet. cheers, On Thu, Mar 13, 2008 at 4:00 AM, Ian Mallett <[EMAIL PROTECTED]> wrote: > > > On Tue, Mar 11, 2008 at 10:32 PM, René Dudfield <[EMAIL PROTECTED]> wrote: > > Hello, > > > > I noticed with this cool shadow demo: > > http://www.pygame.org/project/556/ > > > > On this ATI card I have, I had to change the glAlphaFunc to use > > GL_LESS... which I think is because of float inaccuracies. > > > > #Set alpha test to discard false comparisons > > #glAlphaFunc(GL_EQUAL, 1.0) > > glAlphaFunc(GL_LESS, 1.0) > > > > Any ideas on how to make the shadows softer? Either by making the > > shadow map a higher resolution or some other algorithm? I tried > > changing shadowMapSize = 2048, but it looks like the shadow map is > > wrong some how. Like it isn't the correct scale, or something. > > > I tried increasing the shadow map resolution, but although the resulting > shadow was very nice and smooth, the area it covered on the landscape was > tiny. The resolution appeared to be inversely proportional to the area that > could be shadowed. I think a well-commented simple demo that shadowed a > single quad with another quad might actually be more useful than a > full-blown demo such as this. > > cheers, > > > Ian >
