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Texture Mapping Issues


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#1 theJuniorOne   Members   -  Reputation: 100

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Posted 14 March 2012 - 04:03 AM

Hi, I have been working on a project for school and I am having some problems with texturing a model after I load it from a file. The models seem to all be load and drawn fine, but the textures appear to just be placed anywhere they want on the model itself. as see below.

model loader.png

below is the code involved aswell

Load the Model

ObjectModelType * LoadObjectModel(char *data, int datasize)
{
Vector3f objboundingboxmin(9999,9999,9999);
Vector3f objboundingboxmax(0,0,0);
char *memoryPositionPtr, *endOfMemoryPtr;
int c=0, polyCtr=0, vertexCtr=0, uvCtr=0, normalCtr=0;
ObjectModelType *theModel;
theModel = (ObjectModelType *)calloc(1,sizeof(ObjectModelType));
memoryPositionPtr = data;						   // current position and end location pointers
endOfMemoryPtr = data + datasize;
   while (memoryPositionPtr != endOfMemoryPtr)
{
	  if (*memoryPositionPtr == 'v')
	 //	   theModel->VertexCount++;	  // removed
		 if (*(memoryPositionPtr+1) == 't') // added
			theModel->UVvertexCount++; // added
   else if (*(memoryPositionPtr+1) == 'n')
	theModel->NormalCount++;
		 else							   // added
			theModel->VertexCount++;		// added
	  else if (*memoryPositionPtr == 'f')
		 theModel->PolygonCount++;
	  while (*memoryPositionPtr++ != 0x0A)
		 ;
   }
   //allocate memory for the model data
   theModel->VertexArray = (ObjectVertexType *)malloc(sizeof(ObjectVertexType)*theModel->VertexCount);
   theModel->NormalArray = (ObjectNormalType *)malloc(sizeof(ObjectNormalType)*theModel->NormalCount);// now allocate the arrays
   theModel->UVArray = (ObjectUVType *)malloc(sizeof(ObjectUVType)*theModel->UVvertexCount);   // added
   theModel->PolygonArray = (ObjectPolygonType *)malloc(sizeof(ObjectPolygonType)*theModel->PolygonCount);

   memoryPositionPtr = data;		  // finally, go back and scan the values
vertexCtr = 1;
polyCtr = uvCtr = 0;	  // reset values	 // added  modified
while (memoryPositionPtr != endOfMemoryPtr)
   {
	  if (*memoryPositionPtr=='v')	// might be a vertex or a uv coord
	  {
		 if (*(memoryPositionPtr+1) == 't') // it's a uv coord
		 {
			sscanf(memoryPositionPtr,"vt %f %f",&theModel->UVArray[uvCtr].u,
											   &theModel->UVArray[uvCtr].v);
			uvCtr++;
		 }
   else if (*(memoryPositionPtr+1) == 'n') // it's a normal coord
		 {
			sscanf(memoryPositionPtr,"v %f %f %f",&theModel->NormalArray[normalCtr].x,
											   &theModel->NormalArray[normalCtr].y,
											   &theModel->NormalArray[normalCtr].z);
			normalCtr++;
		 }
		 else							  // no, it's a vertex
		 {
			sscanf(memoryPositionPtr,"v %f %f %f",&theModel->VertexArray[vertexCtr].x,
											   &theModel->VertexArray[vertexCtr].y,
											   &theModel->VertexArray[vertexCtr].z);
   if (objboundingboxmin.x > theModel->VertexArray[vertexCtr].x)
   {
   objboundingboxmin.x = theModel->VertexArray[vertexCtr].x;
   theModel->bbminx = objboundingboxmin.x;
   }
   if (objboundingboxmin.y > theModel->VertexArray[vertexCtr].y)
   {
   objboundingboxmin.y = theModel->VertexArray[vertexCtr].y;
   }
   if (objboundingboxmin.z > theModel->VertexArray[vertexCtr].z)
   {
   objboundingboxmin.z = theModel->VertexArray[vertexCtr].z;
   }
   if (objboundingboxmax.x < theModel->VertexArray[vertexCtr].x)
   {
   objboundingboxmax.x = theModel->VertexArray[vertexCtr].x;
   }
   if (objboundingboxmax.y < theModel->VertexArray[vertexCtr].y)
   {
   objboundingboxmax.y = theModel->VertexArray[vertexCtr].y;
   }
   if (objboundingboxmax.z < theModel->VertexArray[vertexCtr].z)
   {
   objboundingboxmax.z = theModel->VertexArray[vertexCtr].z;
   }
   theModel->bbminx = objboundingboxmin.x;
   theModel->bbminy = objboundingboxmin.y;
   theModel->bbminz = objboundingboxmin.z;
   theModel->bbmaxx = objboundingboxmax.x;
   theModel->bbmaxy = objboundingboxmax.y;
   theModel->bbmaxz = objboundingboxmax.z;
			vertexCtr++;
		 }
	  }
	  else if (*memoryPositionPtr=='f')
	  {
		 sscanf(memoryPositionPtr,"f %d/%d/%d %d/%d/%d %d/%d/%d ",
					&theModel->PolygonArray[polyCtr].Vertex[0],&theModel->PolygonArray[polyCtr].UV[0],&theModel->PolygonArray[polyCtr].Normal[0], // added  modified
					&theModel->PolygonArray[polyCtr].Vertex[1],&theModel->PolygonArray[polyCtr].UV[1],&theModel->PolygonArray[polyCtr].Normal[1], // added  modified
					&theModel->PolygonArray[polyCtr].Vertex[2],&theModel->PolygonArray[polyCtr].UV[2],&theModel->PolygonArray[polyCtr].Normal[2]);// added  modified
		 polyCtr++;
	  }
	
	  while (*memoryPositionPtr++ != (char) 0x0A)
		 ;
   }
   return theModel;
}
//#include <direct.h>  /* supports _getcwd to get the current working directory if their are problems finding the file */
long LoadObjectFile(const char* filename, char** data)
{
long bytes = 0;
FILE* theFile;
//   char buffer[_MAX_PATH];  _getcwd( buffer, _MAX_PATH ); /* Get the current working directory: */
   theFile = fopen(filename, "rt");
if (theFile != NULL)
   {
	fseek(theFile, 0, SEEK_END);
	long end = ftell(theFile);
	fseek(theFile, 0, SEEK_SET);
  
	*data = (char*) malloc(end);
	bytes = (long)fread(*data, sizeof(char), (size_t)end, theFile);
	fclose(theFile);
   }
return bytes;
}

Loading and Applying Textures

void Entity::loadImage(const char* filename)
{
	ILuint ilimg;
	ilGenImages(1, &ilimg);
	ilBindImage(ilimg);
//load image
if(!ilLoadImage(filename))
{
  printf("Error: Could load image %s\n", filename);
  return;
}
	glGenTextures(1, &image);
	glBindTexture(GL_TEXTURE_2D, image);
ILuint bpp = ilGetInteger(IL_IMAGE_BPP);
	ILuint width = ilGetInteger(IL_IMAGE_WIDTH);
	ILuint height = ilGetInteger(IL_IMAGE_HEIGHT);
	ILuint format = ilGetInteger(IL_IMAGE_FORMAT);
ILubyte *data = ilGetData();
glPixelStorei(GL_UNPACK_ALIGNMENT,1);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
   glTexImage2D(GL_TEXTURE_2D, 0, bpp, width, height, 0, format,
		GL_UNSIGNED_BYTE, data);
	ilDeleteImages(1, &ilimg);
}
void Entity :: ApplyTexture()
{
glEnable(GL_NORMALIZE);
glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE, GL_MODULATE);
glBindTexture(GL_TEXTURE_2D,image);
glEnable(GL_REPEAT);
}

Drawing the model
void Entity::draw()
{
/*draw the object in opengl to current location*/
glPushMatrix();
glColor3f(1,1,1);
  glTranslatef(
   currentAnimState->position.x,
   currentAnimState->position.y,
   currentAnimState->position.z);

  //ApplyTexture();
   for(long i=0; i<currentPose->PolygonCount;i++)
   {
	long v1 =  currentPose->PolygonArray[i].Vertex[0];
	long v2 =  currentPose->PolygonArray[i].Vertex[1];
	long v3 =  currentPose->PolygonArray[i].Vertex[2];
	long uv1 =  currentPose->PolygonArray[i].UV[0];
	long uv2 =  currentPose->PolygonArray[i].UV[1];
	long uv3 =  currentPose->PolygonArray[i].UV[2];
	long vn1 =  currentPose->PolygonArray[i].Normal[0];
	long vn2 =  currentPose->PolygonArray[i].Normal[1];
	long vn3 =  currentPose->PolygonArray[i].Normal[2];
	ApplyTexture();
	glBegin(GL_TRIANGLES);

	 //point 1
	 glNormal3f(currentPose->NormalArray[vn1].x,currentPose->NormalArray[vn1].y,currentPose->NormalArray[vn1].z);
	 glTexCoord2f(currentPose->UVArray[uv1].u,currentPose->UVArray[uv1].v);
	 glVertex3f(currentPose->VertexArray[v1].x,currentPose->VertexArray[v1].y,currentPose->VertexArray[v1].z );
  
	 //point 2
	 glNormal3f(currentPose->NormalArray[vn2].x,currentPose->NormalArray[vn2].y,currentPose->NormalArray[vn2].z);
	 glTexCoord2f(currentPose->UVArray[uv2].u,currentPose->UVArray[uv2].v);
	 glVertex3f(currentPose->VertexArray[v2].x,currentPose->VertexArray[v2].y,currentPose->VertexArray[v2].z );
	
	 //point 3
	 glNormal3f(currentPose->NormalArray[vn3].x,currentPose->NormalArray[vn3].y,currentPose->NormalArray[vn3].z);
	 glTexCoord2f(currentPose->UVArray[uv3].u,currentPose->UVArray[uv3].v);
	 glVertex3f(currentPose->VertexArray[v3].x,currentPose->VertexArray[v3].y,currentPose->VertexArray[v3].z );
	glEnd();
   }
  
glPopMatrix();
}


any help would really be appreciated, I have spent many long nights trying to figure this out, also let me know If you want to me to include any other code. Thanks in advance.

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#2 meeshoo   Members   -  Reputation: 508

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Posted 14 March 2012 - 06:47 AM

To me it looks like your UV coordinates are not the right ones.

#3 theJuniorOne   Members   -  Reputation: 100

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Posted 14 March 2012 - 07:50 AM

Yeah that is what I figured but I cant figure out why and I have asked my artist over and over again if its UV mapped correctly and according to him and maya it is. So I dont know why it is getting incorrect values for the UV's

#4 Molle85   Members   -  Reputation: 172

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Posted 14 March 2012 - 07:55 AM

Try flipping the texture coordinates on Y-axis

#5 theJuniorOne   Members   -  Reputation: 100

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Posted 14 March 2012 - 11:39 AM

Yeah Thanks for the quick response, one of the other programmers was actually able to come up with that solution and it worked, thanks though.




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