void ParsePrimitiveList(UInt16 address)
{
// get pointer to vertex list
VertexTableAddr = Memory[address++];
for (; ;)
{
// get primitive pointer
UInt16 primitiveAddress = Memory[address++];
// exit when end of primitive list is encountered
if (primitiveAddress >= 0x8000)
{
return;
}
// get control flags
PrimitiveInstruction opCode = Memory[address++];
// fill vertex buffer
bool faceVisible = RenderPrimitive(primitiveAddress, opCode);
// keep/remove hidden surface 'groups'/'chunks'
if (opCode.IsBranchInstruction)
{
// assume we will branch (this takes care of BRA states)
bool branch = true;
switch (opCode.BranchType)
{
case PrimitiveInstruction.eBranchType.BranchIfFaceHidden: branch = !faceVisible; break;
case PrimitiveInstruction.eBranchType.BranchIfFaceVisible: branch = faceVisible; break;
}
if (!branch)
{
address++;
}
else if (opCode.IsBranchRelative)
{
address += Memory[address]; // NOTE: branch is Int16, could jump forward or backward
}
else
{
address = Memory[address];
}
}
}
}
bool RenderPrimitive(UInt16 address, PrimitiveInstruction opCode)
{
float shade = 0;
// check if first vertex is a normal vector
VertexInstruction vertex = Memory[address];
if (vertex.IsNormalVector)
{
// get the normal vector
Vector3 normal = GetVertexFromTable(vertex);
normal = Vector3.Transform(normal, Parent.WorldRotation);
// get the first coordinate
Vector3 pt = GetVertexFromTable(Memory[address + 1]);
pt = Vector3.Transform(pt, Parent.D3DTS_WORLD);
// check if surface is visible
if (Vector3.Dot(normal, pt) <= 0)
{
return(false); // not visible
}
// if shading enabled
if (opCode.IsShaded)
{
// both values are 14 bit fractional precision
// so dot product must be dividied by 2^(14+14) to normalize from 0.0 - 1.0
// but then we multiply by 8 (2^3) to convert to a pallete index
// so we divide by 2^(14+14-3)
const float scale = 1.0f / (1 << 25);
shade = Vector3.Dot(normal, Parent.Light) * scale;
shade = Math.Min(7, Math.Max(0, shade));
}
}
// should we skip rendering?
if (opCode.SkipRender)
{
return(true); // would have been visible
}
// prepare the vertex buffer
BuildPrimitive(address, Parent.GetColor(opCode.ColorIndex, shade), opCode.RenderMode);
return(true);
}
