shamus88
Joined: 27 Nov 2008
Posts: 2
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 Posted: Fri Dec 05, 2008 10:11 am Post subject: Re: Terrain generation using heightmaps |
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Hmmm, noone at all? :(
I can draw a flat terrain consisting of triangle strips zig zagging from left to right , producing a flat patch. But any attempts at modifying the code to accept data from RAW files made the PS2 crash so far. Here is the relevant part of the code I hope someone could help me with :
| Code: |
void CTerrain::LoadTerrainData(void)
{
// Get the address that we can call to later.
m_iStaticAddr = VIFStaticDMA.GetPointer();
VIFStaticDMA.Add32(FLUSH); // Make sure VU1 isn't busy
VIFStaticDMA.Add32(STCYCL(1,1)); // Unpack linearly, i.e. don't skip any spaces
VIFStaticDMA.Add32(BASE(32)); // The double buffers start at VU1 address 16 (giving us 16 QW to store data that won't change)
VIFStaticDMA.Add32(OFFSET(496)); // The size of each buffer.
VIFStaticDMA.AddUnpack(V4_32, 0, 1); // Unpack 8QW of data that won't change
VIFStaticDMA.AddVector(Vector4(2048, 2048, (0xFFFFFF / 32.0f), 1)); // 0: The scales
// Set the PRIM field here. This may look like it's for convenience, but actually it's the only
// way we can do it. If we set this in the GIFTag it would reset the strip every buffer.
// As we want one huge strip, we can't use the prim setting capabilites of the GIFTag.
VIFStaticDMA.StartDirect();
VIFStaticDMA.StartAD();
VIFStaticDMA.AddAD(PRIM_SET(GS_TRISTRIP, 1, 1, 0, 0, 0, 0, 0, 0), PRIM);
VIFStaticDMA.EndAD();
VIFStaticDMA.EndDirect();
// The verts are 3QW each, and the 504QW is split in half. Therefore we have 252QW for each buffer.
// Each buffer also has 2QW of info (GIFTag + Numverts), so we can process 83 vertices (249QW)
// in each buffer.
int iNumVertsPerChunk = 82;
// The number of triangles in each dimension.
int iSizeX = 256;
int iSizeY = 256;
int iNumVerts = (iSizeX * 2) * (iSizeY - 1);
int iX = 0, iY = 0;
int bBottomRow = 0;
bool bFirst = true;
while(iNumVerts > 0)
{
int iVertsThisChunk;
if(iNumVerts > iNumVertsPerChunk)
{
iVertsThisChunk = iNumVertsPerChunk;
iNumVerts -= iVertsThisChunk;
}
else
{
iVertsThisChunk = iNumVerts;
iNumVerts -= iVertsThisChunk;
}
VIFStaticDMA.AddUnpack(V4_32, 0, iVertsThisChunk * 3 + 2, 1);
VIFStaticDMA.Add128(iVertsThisChunk * 3);
VIFStaticDMA.Add128(
GS_GIFTAG_BATCH(iVertsThisChunk,
1, 0, 0, GIF_FLG_PACKED,
GS_BATCH_3(GIF_REG_ST, GIF_REG_RGBAQ, GIF_REG_XYZ2)));
// Zigzag from left to right across the patch making a huge triangle strip.
//
// 0 2 4 6
// | / | / | / |
// | / | / | / |
// 1 / 3 / 5 / 7 etc.
//
for(int iVert = 0; iVert < iVertsThisChunk; iVert++)
{
float fX = (float)iX;
float fY = (float)(iY + bBottomRow);
// Disable the drawing kick when we move to the next row, so that we don't get a huge
// polygon going across the patch.
int iDontDraw = (iX == 0) ? 1 : 0;
// Alternate between the current row and the one below.
iX += bBottomRow;
bBottomRow ^= 1;
// If we have reached the end, start again on the next row.
if(iX == iSizeX)
{
iX = 0;
bBottomRow = 0;
iY += 1;
}
// Add a huge number of vertices
VIFStaticDMA.AddVector(Vector4(fX / iSizeX, fY / iSizeY, 1, *((float *)&iDontDraw))); // Tex coords + in W, a flag to set ADC or not.
VIFStaticDMA.AddVector(Vector4(0, 1, 0, 0)); // Normal
VIFStaticDMA.AddVector(Vector4((fX - (iSizeX / 2)), 0, (fY - (iSizeY / 2)), 1)); // Position
}
if(bFirst)
{
bFirst = false;
// If this is the first buffer then run the VU code from address 0 so that the initialisation
// VU code is ran.
VIFStaticDMA.Add32(MSCALL(0));
}
else
{
// For multiple times MSCNT means to continue where the VU code finished last time at the --cont.
VIFStaticDMA.Add32(MSCNT);
}
// Notice that due to the quad buffer setup we don't need to flush here because we can upload, process, and render
// all in parallel now. (the XGKick in the vector code will flush to make sure that we don't get ahead of ourselves)
}
VIFStaticDMA.Add32(FLUSH);
VIFStaticDMA.DMARet();
}
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Thanks. |
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