3ds.cpp

3DS文件读取程序 用于三维开发的；用于三维开发的；

//***********************************************************************//
//																		 //
//		- "Talk to me like I'm a 3 year old!" Programming Lessons -		 //
//                                                                       //
//		$Author:		DigiBen		[e-mail]			 //
//																		 //
//		$Program:		3DS Loader										 //
//																		 //
//		$Description:	Demonstrates how to load a .3ds file format		 //
//																		 //
//		$Date:			10/6/01											 //
//																		 //
//***********************************************************************//

#include "main.h"
#include "3ds.h"
#include <assert.h>

// Global
int gBuffer[50000] = {0};					// This is used to read past unwanted data

// This file handles all of the code needed to load a .3DS file.
// Basically, how it works is, you load a chunk, then you check
// the chunk ID.  Depending on the chunk ID, you load the information
// that is stored in that chunk.  If you do not want to read that information,
// you read past it.  You know how many bytes to read past the chunk because
// every chunk stores the length in bytes of that chunk.

///////////////////////////////// CLOAD3DS \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
/////
/////	This constructor initializes the tChunk data
/////
///////////////////////////////// CLOAD3DS \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*

CLoad3DS::CLoad3DS()
{
	m_FilePointer = NULL;
}

///////////////////////////////// IMPORT 3DS \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
/////
/////	This is called by the client to open the .3ds file, read it, then clean up
/////
///////////////////////////////// IMPORT 3DS \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*

bool CLoad3DS::Import3DS(t3DModel *pModel, char *strFileName)
{
	char strMessage[255] = {0};
	tChunk currentChunk = {0};

	// Open the 3DS file
	m_FilePointer = fopen(strFileName, "rb");

	// Make sure we have a valid file pointer (we found the file)
	if(!m_FilePointer) 
	{
		sprintf(strMessage, "Unable to find the file: %s!", strFileName);
		MessageBox(NULL, strMessage, "Error", MB_OK);
		return false;
	}

	// Once we have the file open, we need to read the very first data chunk
	// to see if it's a 3DS file.  That way we don't read an invalid file.
	// If it is a 3DS file, then the first chunk ID will be equal to PRIMARY (some hex num)

	// Read the first chuck of the file to see if it's a 3DS file
	ReadChunk(&currentChunk);

	// Make sure this is a 3DS file
	if (currentChunk.ID != PRIMARY)
	{
		sprintf(strMessage, "Unable to load PRIMARY chuck from file: %s!", strFileName);
		MessageBox(NULL, strMessage, "Error", MB_OK);
		return false;
	}

	// Now we actually start reading in the data.  ProcessNextChunk() is recursive

	// Begin loading objects, by calling this recursive function
	ProcessNextChunk(pModel, &currentChunk);

	// After we have read the whole 3DS file, we want to calculate our own vertex normals.
	ComputeNormals(pModel);

	// Clean up after everything
	CleanUp();

	return true;
}

///////////////////////////////// CLEAN UP \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
/////
/////	This function cleans up our allocated memory and closes the file
/////
///////////////////////////////// CLEAN UP \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*

void CLoad3DS::CleanUp()
{
	if (m_FilePointer) {
		fclose(m_FilePointer);					// Close the current file pointer
		m_FilePointer = NULL;
	}
}


///////////////////////////////// PROCESS NEXT CHUNK\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
/////
/////	This function reads the main sections of the .3DS file, then dives deeper with recursion
/////
///////////////////////////////// PROCESS NEXT CHUNK\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*

void CLoad3DS::ProcessNextChunk(t3DModel *pModel, tChunk *pPreviousChunk)
{
	t3DObject newObject = {0};					// This is used to add to our object list
	tMaterialInfo newTexture = {0};				// This is used to add to our material list

	tChunk currentChunk = {0};					// The current chunk to load
	tChunk tempChunk = {0};						// A temp chunk for holding data		

	// Below we check our chunk ID each time we read a new chunk.  Then, if
	// we want to extract the information from that chunk, we do so.
	// If we don't want a chunk, we just read past it.  

	// Continue to read the sub chunks until we have reached the length.
	// After we read ANYTHING we add the bytes read to the chunk and then check
	// check against the length.
	while (pPreviousChunk->bytesRead < pPreviousChunk->length)
	{
		// Read next Chunk
		ReadChunk(&currentChunk);

		// Check the chunk ID
		switch (currentChunk.ID)
		{
		case VERSION:							// This holds the version of the file
			
			// If the file was made in 3D Studio Max, this chunk has an int that 
			// holds the file version.  Since there might be new additions to the 3DS file
			// format in 4.0, we give a warning to that problem.
			// However, if the file wasn't made by 3D Studio Max, we don't 100% what the
			// version length will be so we'll simply ignore the value

			// Read the file version and add the bytes read to our bytesRead variable
			currentChunk.bytesRead += fread(gBuffer, 1, currentChunk.length - currentChunk.bytesRead, m_FilePointer);

			// If the file version is over 3, give a warning that there could be a problem
			if ((currentChunk.length - currentChunk.bytesRead == 4) && (gBuffer[0] > 0x03)) {
				MessageBox(NULL, "This 3DS file is over version 3 so it may load incorrectly", "Warning", MB_OK);
			}
			break;

		case OBJECTINFO:						// This holds the version of the mesh
			{	
			// This chunk holds the version of the mesh.  It is also the head of the MATERIAL
			// and OBJECT chunks.  From here on we start reading in the material and object info.

			// Read the next chunk
			ReadChunk(&tempChunk);

			// Get the version of the mesh
			tempChunk.bytesRead += fread(gBuffer, 1, tempChunk.length - tempChunk.bytesRead, m_FilePointer);

			// Increase the bytesRead by the bytes read from the last chunk
			currentChunk.bytesRead += tempChunk.bytesRead;

			// Go to the next chunk, which is the object has a texture, it should be MATERIAL, then OBJECT.
			ProcessNextChunk(pModel, &currentChunk);
			break;
		}
		case MATERIAL:							// This holds the material information

			// This chunk is the header for the material info chunks

			// Increase the number of materials
			pModel->numOfMaterials++;

			// Add a empty texture structure to our texture list.
			// If you are unfamiliar with STL's "vector" class, all push_back()
			// does is add a new node onto the list.  I used the vector class
			// so I didn't need to write my own link list functions.  
			pModel->pMaterials.push_back(newTexture);

			// Proceed to the material loading function
			ProcessNextMaterialChunk(pModel, &currentChunk);
			break;

		case OBJECT:							// This holds the name of the object being read
				
			// This chunk is the header for the object info chunks.  It also
			// holds the name of the object.

			// Increase the object count
			pModel->numOfObjects++;
		
			// Add a new tObject node to our list of objects (like a link list)
			pModel->pObject.push_back(newObject);
			
			// Initialize the object and all it's data members
			memset(&(pModel->pObject[pModel->numOfObjects - 1]), 0, sizeof(t3DObject));

			// Get the name of the object and store it, then add the read bytes to our byte counter.
			currentChunk.bytesRead += GetString(pModel->pObject[pModel->numOfObjects - 1].strName);
			
			// Now proceed to read in the rest of the object information
			ProcessNextObjectChunk(pModel, &(pModel->pObject[pModel->numOfObjects - 1]), &currentChunk);
			break;

		case EDITKEYFRAME:

			// Because I wanted to make this a SIMPLE tutorial as possible, I did not include
			// the key frame information.  This chunk is the header for all the animation info.
			// In a later tutorial this will be the subject and explained thoroughly.

			//ProcessNextKeyFrameChunk(pModel, currentChunk);

			// Read past this chunk and add the bytes read to the byte counter
			currentChunk.bytesRead += fread(gBuffer, 1, currentChunk.length - currentChunk.bytesRead, m_FilePointer);
			break;

		default: 
			
			// If we didn't care about a chunk, then we get here.  We still need
			// to read past the unknown or ignored chunk and add the bytes read to the byte counter.
			currentChunk.bytesRead += fread(gBuffer, 1, currentChunk.length - currentChunk.bytesRead, m_FilePointer);
			break;
		}

		// Add the bytes read from the last chunk to the previous chunk passed in.
		pPreviousChunk->bytesRead += currentChunk.bytesRead;
	}
}


///////////////////////////////// PROCESS NEXT OBJECT CHUNK \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
/////
/////	This function handles all the information about the objects in the file
/////
///////////////////////////////// PROCESS NEXT OBJECT CHUNK \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*

void CLoad3DS::ProcessNextObjectChunk(t3DModel *pModel, t3DObject *pObject, tChunk *pPreviousChunk)
{
	// The current chunk to work with
	tChunk currentChunk = {0};

	// Continue to read these chunks until we read the end of this sub chunk
	while (pPreviousChunk->bytesRead < pPreviousChunk->length)
	{
		// Read the next chunk
		ReadChunk(&currentChunk);

		// Check which chunk we just read
		switch (currentChunk.ID)
		{
		case OBJECT_MESH:					// This lets us know that we are reading a new object
		
			// We found a new object, so let's read in it's info using recursion
			ProcessNextObjectChunk(pModel, pObject, &currentChunk);
			break;

		case OBJECT_VERTICES:				// This is the objects vertices
			ReadVertices(pObject, &currentChunk);
			break;

		case OBJECT_FACES:					// This is the objects face information
			ReadVertexIndices(pObject, &currentChunk);
			break;

		case OBJECT_MATERIAL:				// This holds the material name that the object has
			
			// This chunk holds the name of the material that the object has assigned to it.
			// This could either be just a color or a texture map.  This chunk also holds
			// the faces that the texture is assigned to (In the case that there is multiple
			// textures assigned to one object, or it just has a texture on a part of the object.
			// Since most of my game objects just have the texture around the whole object, and 
			// they aren't multitextured, I just want the material name.

			// We now will read the name of the material assigned to this object
			ReadObjectMaterial(pModel, pObject, &currentChunk);			
			break;

		case OBJECT_UV:						// This holds the UV texture coordinates for the object

			// This chunk holds all of the UV coordinates for our object.  Let's read them in.
			ReadUVCoordinates(pObject, &currentChunk);
			break;

		default:  

			// Read past the ignored or unknown chunks
			currentChunk.bytesRead += fread(gBuffer, 1, currentChunk.length - currentChunk.bytesRead, m_FilePointer);
			break;
		}

		// Add the bytes read from the last chunk to the previous chunk passed in.
		pPreviousChunk->bytesRead += currentChunk.bytesRead;
	}
}


///////////////////////////////// PROCESS NEXT MATERIAL CHUNK \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
/////
/////	This function handles all the information about the material (Texture)
/////
///////////////////////////////// PROCESS NEXT MATERIAL CHUNK \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*

void CLoad3DS::ProcessNextMaterialChunk(t3DModel *pModel, tChunk *pPreviousChunk)
{