forums.ps2dev.org

onne · Joined: 29 Aug 2006 Posts: 24

For those who are interested seeing some C++ and VFPU code this engine offers that and pixel processing rendering engine for PSP. (I used PSPSDK, Eclipse & Cygwin as my environment..)

Basically it has a scanline renderer, which allows different kinds of interpolations per pixel bases. It is not directed to game development as such, but more for exploring different kinds of rendering/shading types on PSP.

Included in the engine:
- a simple scenegraph
- OBJ loader
- scaline renderer (this is where the most bugs seem to be.. :) )
- Phong, Gouraud and Quadratic shaders implemented
- VFPU used for the rendering pipeline transforms, occlusion culling, and lighting calculations
- Simple multithreading for UI
- UI (rotate & zoom)

Current Issues:
- the scanline algorithm produces uggly flickering.. maybe because of writing directly to memory... (maybe someone would have an idea about this?)
- scanline does not draw to the right hand side 32 pixels...hmmm.. related to the above, maybe.
- And I believe the scanline could be faster as well!!!
- The normals are not drawn correctly now...
- Code could be cleaned more I guess

Todo (I'm not sure if I have the time anymore though...):
- Fix the above bugs
- File menu for loading objects
- textures, cubemaps, hdr, blooming, simple modelling capabilities, etc, etc... :)

Usage:
0. copy the eboot AND the data folder + contents on your psp
1. start the program and press X when the model has been loaded
2. Use analogue stick to rotate L&R to zoom and [] & /\ to change the active renderer.

Download:

*UPDATED 2007-07-08 (fixed phong shading as discussed below)
*UPDATED 2007-07-10 (optimized vfpu stuff as discussed below)
http://www.etukan.net/psp/rtEngine.zip (1.75MB)

The thanks go to:
ps2dev.org, hlide(VFPU), tyranid(PSPLINK!), torakak(Eclipse), skistovel(PSPGU), rapso (founding phong bug)

an example with a model of 5000 polys and 3842 vertices

onne · Joined: 29 Aug 2006 Posts: 24

I got question about creating custom shaders in the DX or GLSL style, using vertex- and pixel/fragment- shading programs... So I thought others might be interested as well.

-----------------------------

As you know there is really no shading language on PSP, but we have to do the things ourselves. That was the exact purpose of the engine I wrote... So,

* in Gouraud shader:
-- the normals are taken only per vertex basis
-- the color got using the "(vertex) shader program" (and pixel coordinates of course) is interpolated per fragment.

* in Phong shader
-- the normals are interpolated per fraqment basis
-- color information is calculated per fragment (using the "(fragment) shader program")

* in Quadratic shader the formulation is more complex
-- normals are interpolated once in the edge midpoints
-- color is calculated per fragment using quadratic formulation

In other words, in the Gouraud case the shader program ( CalculateLightVFPU() ) is called per vertex, where as in the Phong case it is called per fragment.

Following that pattern one can implement any shader... although the cost of interpolation is quite high as you can see. But in the case of smaller models (<1000) results may both look very nice and be real time.

And of course it is possible to use shaders only on some objects instead of all!

rapso · Joined: 28 Mar 2005 Posts: 148

hi

nice work! I've taken a look at ur assembler code, I'm not that deep into vfpu code, but it seems like u've forgot some normalize, that are needed per pixel. sorry if u do it and I just didn't find it, maybe I'm to tired ;)

nite

onne · Joined: 29 Aug 2006 Posts: 24

thanks rapso... Yes, maybe the normalization is a bit in a weird place, but it is there. In the code the light vector is static and normalized, and so is the view...

So the only thing that needs normalization is the normals. They are normalized when the appropriate transform is applied in the ApplyNormalMatrix().

rapso · Joined: 28 Mar 2005 Posts: 148

yes, I've seen that normalize per vertex, but I'm talking about

onne · Joined: 29 Aug 2006 Posts: 24

yep, I see it... I'm just thinking how much it improves the accuracy. :)

(..I guess it should a lot as the intensity of many highlights decreases when interpolating...)

Actually the phong and gouraud both use the same CalculateLightVFPU() function, so only the phong needs the normalization...

I will try how much it improves the quality and update the archieve, thanks for the notice!

-----------------
UPDATED the zip...
yes the quality is better and phongshading works as it should (I added a seperate lighting function CalculateLightVFPUPhong() ). thanks.

hlide · Joined: 10 Sep 2006 Posts: 753

some operations can be reduced through parallelization :

vadd.s has 3 cycles penality because of RAW

onne · Joined: 29 Aug 2006 Posts: 24

ah... I forgot to group those. Thanks! Although I did not know about RAW... interesting.

It seems I should upload it to some svn... updating the zip starts to get me. heh.

What still bothers me are the artifacts in the scanline. I'm not quite sure where those come from.

Oh, and hlide.. I have this part in the code:

hlide · Joined: 10 Sep 2006 Posts: 753

hlide · Joined: 10 Sep 2006 Posts: 753

svxs · Joined: 19 Jun 2009 Posts: 15

Does anyone have a working link for this old project? Sounds interesting. I'd like to have a look.

Tomaz · Joined: 25 Aug 2006 Posts: 6

I'd also like to know if anyone still got this?