FIX: Assumption in terrData.h breaks some terrain mods

A "bug" in terrData.h will cause resources such as this one or the one on CodeSampler.com to crash Torque. (These resources allow you to use more than the default eight materials that can be assigned to a terrain map.)

In terrData.h, on line 192:

S32 mMPMIndex[10];

This assumes a maximum of nine possible materials. While this is fine for out-of-the-box Torque, this assumption will cause an error in TerrainBlock::initMMXBlender at line 608 if you have either of the above-mentioned resources installed. (mFile will contain gibberish at that line, and the getMaterialAlphaMap method will choke.)

I traced this back to the onAdd() method, where this code executes at line 749:

for (int i = 0; i < TerrainBlock::MaterialGroups; i++)
   {                        
      StringTableEntry fn = mMaterialFileName[i];
      if (fn != NULL)
      {   
			if(!dStrncmp(fn, "terrain.", 8))
				fn += 8;

			char nameBuff[512];
			dStrcpy(nameBuff, mTerrFileName);
			const char *p = dStrrchr(fn, '/');
			if(p) p++;
			else p = nameBuff;

			mMPMIndex[i] = pMatMap->getIndexFromName( p );
      }
      else mMPMIndex[i] = -1;
   }

Ooops! After nine loops, mMPMIndex walks off and clobbers the heap, which causes the later crash. Well, the fix is simple. Change terrData.h line 192 to read:

S32 mMPMIndex[TerrainBlock::MaterialGroups];

Problem solved!

It's not a big deal, but might be a good, fast change to prevent future hair-tearing. :)