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sceGumDrawArray and huge models

 
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LuMo



Joined: 21 Aug 2005
Posts: 410
Location: Austria
PostPosted: Wed Jan 18, 2006 10:39 pm    Post subject: sceGumDrawArray and huge models Reply with quote
as sceGumDrawArray is defined:
Code:
void sceGumDrawArray     (      int       prim,
      int     vtype,
      int     count,
      const void *     indices,
      const void *     vertices
   )


if i pass to count a value like unsigned shor it works fine
when i switch over to unsigned long the model gets fucked up (no other changes in code...)

as int can be 2 or 4 bytes i am curious whats going wrong there...
int
-32'768 ... 32'767 or
-2'147'483'648 .. 2'147'483'647

while unsigned long = 4 byte
0 ... 4'294'967'295

the range is the same (IF int is implemented as 4-byte)

any ideas?
greets
lumo
PS: i do not want to crop the models in parts...
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sandberg



Joined: 05 Oct 2005
Posts: 90
Location: Denmark
PostPosted: Thu Jan 19, 2006 2:44 am    Post subject: Reply with quote
This is caused by the fact, that when the sceGuDrawArray sends the last command to the GU, it packs the primitive type and the count parameter into the same 32 bit argument. Where the 16 upper bits is the primitive and the lower 16 bit is the number of vertices / indices. So you can only use 16 bit for the count.

I've marked the code below in red.

Quote:

void sceGuDrawArray(int prim, int vtype, int count, const void* indices, const void* vertices)
{
if (vtype)
sendCommandi(18,vtype);

if (indices)
{
sendCommandi(16,(((unsigned int)indices) >> 8) & 0xf0000);
sendCommandi(2,((unsigned int)indices) & 0xffffff);
}

if (vertices)
{
sendCommandi(16,(((unsigned int)vertices) >> 8) & 0xf0000);
sendCommandi(1,((unsigned int)vertices) & 0xffffff);
}

sendCommandiStall(4,(prim << 16)|count);
}

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LuMo



Joined: 21 Aug 2005
Posts: 410
Location: Austria
PostPosted: Thu Jan 19, 2006 2:57 am    Post subject: Reply with quote
bugga
at least i know... its not my programming fault :)

thanks
lumo
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