core::array<SDefineExp> grabDefineExpressions(core::stringc &shaderProgram)
{
s32 CurrentSearchPos = 1;
s32 FindHelper = 1;
s32 FindHelper2 = 1;
core::array<SDefineExp> DefineArray;
// Dont bother stripping comments if theres no defines.
if((CurrentSearchPos = shaderProgram.find("##ifdef")) == -1)
return DefineArray;
// Strip all comments, they get in the way.
while((CurrentSearchPos = shaderProgram.find("//")) > -1)
{
FindHelper = shaderProgram.findNext('\n',CurrentSearchPos);
if(FindHelper != -1)
for(u32 i = CurrentSearchPos;i < (u32)FindHelper;++i)
shaderProgram[i] = ' ';
else
for(u32 i = CurrentSearchPos;i < shaderProgram.size();++i)
shaderProgram[i] = ' ';
}
while((CurrentSearchPos = shaderProgram.find("/*")) > -1)
{
FindHelper = shaderProgram.find("*/");
if(FindHelper > CurrentSearchPos)
for(u32 i = CurrentSearchPos;i <= (u32)(FindHelper + 1);++i)
shaderProgram[i] = ' ';
else
for(u32 i = CurrentSearchPos;i < shaderProgram.size();++i)
shaderProgram[i] = ' ';
}
while((CurrentSearchPos = shaderProgram.find("##ifdef")) > -1)
{
SDefineExp DExp;
DExp.IfPos = CurrentSearchPos;
// Comment out the ##ifdef so that we do not find it again, and so that the compiler ignores it.
shaderProgram[CurrentSearchPos] = '/';
shaderProgram[CurrentSearchPos + 1] = '/';
FindHelper = shaderProgram.findNext(' ',CurrentSearchPos);
FindHelper2 = shaderProgram.findNext('\n',FindHelper);
if(FindHelper == -1 || FindHelper2 == -1)
{
std::cerr << "Shader preprocessor encountered invalid if statement." << std::endl;
return DefineArray;
}
// Find the appropriate expression and trim all white space.
DExp.IfExp = shaderProgram.subString(FindHelper,FindHelper2 - FindHelper);
DExp.IfExp.trim();
// Record if its inverse and remove ! sign from expression.
if(DExp.IfExp[0] == '!')
{
DExp.IfExp[0] = ' ';
DExp.IfExp.trim();
DExp.Inverse = true;
}
bool EndIfFound = false;
FindHelper2 = CurrentSearchPos;
s32 IfEndScope = 0;
while(!EndIfFound)
{
FindHelper = shaderProgram.findNext('#',FindHelper2);
if(FindHelper == -1 || FindHelper >= (s32)(shaderProgram.size() - 3))
{
std::cerr << "Shader preprocessor encountered unmatched if statement." << std::endl;
return DefineArray;
}
if(IfEndScope < 0)
{
std::cerr << "Shader preprocessor encountered unmatched endif statement." << std::endl;
return DefineArray;
}
if(shaderProgram[FindHelper + 1] != '#')
{
FindHelper2 = FindHelper + 1;
continue;
}
else if(shaderProgram[FindHelper + 2] == 'i')
{
IfEndScope++;
}
else if(shaderProgram[FindHelper + 2] == 'e' && shaderProgram[FindHelper + 3] == 'n')
{
if(IfEndScope == 0)
break;
IfEndScope--;
}
else if(shaderProgram[FindHelper + 2] == 'e' && shaderProgram[FindHelper + 3] == 'l')
{
if(IfEndScope == 0)
{
if(DExp.ElsePos != -1)
{
std::cerr << "Shader preprocessor encountered duplicate else statements per if statement." << std::endl;
return DefineArray;
}
// Comment out the ##else so that we do not find it again, and so that the compiler ignores it.
shaderProgram[FindHelper] = '/';
shaderProgram[FindHelper + 1] = '/';
DExp.ElsePos = FindHelper;
}
}
FindHelper2 = FindHelper + 2;
}
// Comment out the ##endif so that we do not find it again, and so that the compiler ignores it.
shaderProgram[FindHelper] = '/';
shaderProgram[FindHelper + 1] = '/';
DExp.EndPos = FindHelper;
// Add the define expression to the array.
DefineArray.push_back(DExp);
}
return DefineArray;
}
//! PreProcesses a shader using Irrlicht's built-in shader preprocessor.
core::stringc CShaderPreprocessor::ppShader(core::stringc shaderProgram)
{
core::array<SDefineExp> DefineArray = grabDefineExpressions(shaderProgram);
// No need for this as its already inited at startup.
//// If DefineMap is empty then initialize it.
//if(DefineMap.isEmpty())
// initDefineMap();
for(u32 i = 0; i < DefineArray.size();++i)
{
if(DefineArray[i].IfPos == -1)
break;
// Either it is true and not inversed, or it is false, but inversed.
// (Wish C++ had a built-in (logical) XOR operator sometimes. :P)
if((DefineMap.find(DefineArray[i].IfExp) && !DefineArray[i].Inverse)
|| (!DefineMap.find(DefineArray[i].IfExp) && DefineArray[i].Inverse))
{
if(DefineArray[i].ElsePos > -1)
{
// If there is an else statement then clear the else section.
if(DefineArray[i].EndPos != -1)
{
for(int z = DefineArray[i].ElsePos;z <= DefineArray[i].EndPos + 6;++z)
shaderProgram[z] = ' ';
}
}
}
else if(DefineArray[i].ElsePos != -1)
{
// If there is an else statement then clear the if section.
for(int z = DefineArray[i].IfPos;z <= DefineArray[i].ElsePos + 5;++z)
shaderProgram[z] = ' ';
}
else
{
// Else just clear the whole block.
if(DefineArray[i].EndPos != -1)
{
for(int z = DefineArray[i].IfPos;z <= DefineArray[i].EndPos + 6;++z)
shaderProgram[z] = ' ';
}
}
}
core::map<core::stringc,core::stringc>::ParentFirstIterator DefIter;
s32 DefFinder = 1;
// Replace all shader defines.
for(DefIter = DefineMap.getParentFirstIterator();!DefIter.atEnd();DefIter++)
{
if(DefIter->getValue().size() == 0)
continue;
// Replace all occurances.
while((DefFinder = shaderProgram.find(DefIter->getKey().c_str())) > -1)
{
// Clear the define from the code.
for(u32 z = DefFinder;z < DefFinder + DefIter->getKey().size();++z)
shaderProgram[z] = ' ';
// Stitch value and shader program together. (Is there a faster way?)
shaderProgram = shaderProgram.subString(0,DefFinder) + DefIter->getValue()
+ shaderProgram.subString(DefFinder,shaderProgram.size() - 1);
}
}
return shaderProgram;
}