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Can't get gouraud shaded triangles to work

 
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aap



Joined: 05 Jun 2008
Posts: 7
PostPosted: Thu Apr 01, 2010 6:27 pm    Post subject: Can't get gouraud shaded triangles to work Reply with quote
Hey guys,
I recently began to play around with the ps2, which is really fun...but I've run in some troubles.
How the hell can I draw gouraud shaded triangles? I thought it would be a simple matter of setting the right bit in the PRIM register and giving each vertex a different color...turns out it seems to be much harder than I thought.
My code is roughly based on the tutorial by dreamtime, to which I put a link at the end because the one on the main page is dead.
It looks like this:
Code:

GIF_BEGIN_PACKET(gs_dma_buf);
GIF_TAG(gs_dma_buf, 1, 1, 0, 0, 1, 8,   
    (PRIM<<0)  |
    (RGBAQ<<4) |
    (XYZ2<<8)  |
    (RGBAQ<<12)|
    (XYZ2<<16) |
    (RGBAQ<<20)|
    (XYZ2<<24) |
    (GIF_NOP<<28));
gs_dma_buf[gs_dma_buf_cur++] = GS_PRIM(PRIM_TRI, 1, 0, 0, 0, 0, 0, 0, 0);
gs_dma_buf[gs_dma_buf_cur++] = GS_RGBAQ(255, 0, 0, 0, 0);
gs_dma_buf[gs_dma_buf_cur++] = GS_XYZ(x1<<4, y1<<4, 0);
gs_dma_buf[gs_dma_buf_cur++] = GS_RGBAQ(0, 255, 0, 0, 0);
gs_dma_buf[gs_dma_buf_cur++] = GS_XYZ(x2<<4, y2<<4, 0);
gs_dma_buf[gs_dma_buf_cur++] = GS_RGBAQ(0, 0, 255, 0, 0);
gs_dma_buf[gs_dma_buf_cur++] = GS_XYZ(x3<<4, y3<<4, 0);
gs_dma_buf[gs_dma_buf_cur++] = 0;
gs_dma_buf_size = 5;
GIF_SEND_PACKET(gs_dma_buf);

I also tried using A+D Packets and even used working "magic numbers" from gsKit, alas with no success. The triangle is always blue (i.e. the last color I specified).
I really have no idea what could be the problem, the macros are correct, the information is also correct...could it be anything in the initialization routine? Do I have to set up another register properly?
Please give me a hint what could be wrong...

http://aap.papnet.eu/ps2tut_01.zip

Edit: fixed code

Last edited by aap on Thu Apr 01, 2010 6:48 pm; edited 1 time in total
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ragnarok2040



Joined: 09 Aug 2006
Posts: 230
PostPosted: Thu Apr 01, 2010 6:40 pm    Post subject: Reply with quote
It looks like you don't have the GS_PRIM register setting prior to the vertex data in your packet which might be setting your first RGBAQ data into the PRIM register. You should also set the NOP register data to 0 and advance your gs_dma_buf_cur index, just so you make sure you don't use up that data slot in the packet accidentally in case you change it in the future.
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aap



Joined: 05 Jun 2008
Posts: 7
PostPosted: Thu Apr 01, 2010 6:52 pm    Post subject: Reply with quote
Oh, sorry, I forgot to copy that (my code is a mess with huge blocks in comments).
Fixed it, should be correct now...but still doesn't work.
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ragnarok2040



Joined: 09 Aug 2006
Posts: 230
PostPosted: Thu Apr 01, 2010 6:59 pm    Post subject: Reply with quote
Maybe the primitive override is enabled. Try setting PRMODECONT to 1 to turn it off. Or add a PRMODE setting after the PRIM setting, it uses the same GS_PRIM() macro, except it doesn't set the type. You'll need to set it whenever you want to change a primitive's attributes, though.
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aap



Joined: 05 Jun 2008
Posts: 7
PostPosted: Thu Apr 01, 2010 7:07 pm    Post subject: Reply with quote
Woah, thank you. That's the solution :)
I knew it was a simple matter of setting some bits in some register, I just didn't know which one :P
Cool, thanks, that was a quick answer :)
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ragnarok2040



Joined: 09 Aug 2006
Posts: 230
PostPosted: Thu Apr 01, 2010 7:21 pm    Post subject: Reply with quote
No problem, :D.

It's still fresh in my mind because of the new libdraw implementation.
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