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knobby67

loading and drawing a vbo

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Hi All,
I'm trying to load and a display a model using the assimp model loader and VBO's. I'm new to assimp and vbo's so am having a few problems, basically the nothing is displayed. All I'm doing now is reading the vertexes and indexes. I'm hoping someone help me out with using VBO's basically I read in the data using assimp then setting up the vertex and index vbo's as follows


/*get number of meshes*/
number_of_meshes = scene->mNumMeshes;
// For each mesh
for ( unsigned int n = 0; n < scene->mNumMeshes; ++n )
{

struct aiMesh* mesh = scene->mMeshes[n];

/*create face array*/
unsigned int *facearray;
facearray = (unsigned int *)malloc(sizeof(unsigned int) * mesh->mNumFaces * 3);
unsigned int faceIndex = 0;

for ( unsigned int t = 0; t < mesh->mNumFaces; ++t )
{
const struct aiFace* face = &mesh->mFaces[t];
memcpy(&facearray[faceIndex], face->mIndices,3 * sizeof( unsigned int ) );
faceIndex += 3;
}
aMesh.numfaces = scene->mMeshes[n]->mNumFaces;


/*face vbo*/
glGenBuffers( 1, &aMesh.index_vbo );
glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, aMesh.index_vbo );
glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * (mesh->mNumFaces * 3), facearray, GL_STATIC_DRAW);


/* buffer for vertex positions*/
GLfloat *vertexarray;
vertexarray = ( GLfloat *)malloc(sizeof( GLfloat ) * mesh->mNumVertices * 3);
unsigned int vetexindex = 0;

if ( mesh->HasPositions() )
{
for ( unsigned int t = 0; t < mesh->mNumVertices; ++t )
{

vertexarray[ vetexindex ] = mesh->mVertices[ t ].x;
vertexarray[ vetexindex + 1 ] = mesh->mVertices[ t ].y;
vertexarray[ vetexindex + 2 ] = mesh->mVertices[ t ].z;
vetexindex += 3;
}
//GL_ARRAY_BUFFER
glGenBuffers( 1, &aMesh.vertex_vbo );
glBindBuffer( GL_ARRAY_BUFFER, aMesh.vertex_vbo );
glBufferData( GL_ARRAY_BUFFER, sizeof(float) * ( mesh->mNumVertices * 3 ), vertexarray, GL_STATIC_DRAW );
}

aMesh.numvertexes = scene->mMeshes[n]->mNumFaces;

/*degug for faces or elements*/
for( unsigned int x=0; x < mesh->mNumVertices ; ++x )
{
printf("%d array %d x %f y %f z %f \n",x,facearray[ x ], vertexarray[ facearray[ x ] ], vertexarray[ facearray[ x ] + 1 ], vertexarray[ facearray[ x ] + 2 ] );
}

mymeshes.push_back( aMesh );
free( vertexarray );
free( facearray );
}


I can see that vertexarray and facearray contain data from my printf statement. But don't know if the data has been passed to the VBO's?

next I draw the scene using


glPushMatrix( );

for (unsigned int n=0; n < number_of_meshes; n++)
{


printf("\n\n vertex vbo %d index vbo %d \n\n\n",mymeshes.at( n ).vertex_vbo, mymeshes.at( n ).index_vbo );

glBindBuffer(GL_ARRAY_BUFFER, mymeshes.at( n ).vertex_vbo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mymeshes.at( n ).index_vbo );
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, 0 );

glDrawElements(GL_TRIANGLE_STRIP, mymeshes.at( n ).index_vbo, GL_UNSIGNED_INT, 0);

glDisableClientState(GL_VERTEX_ARRAY);

glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);



}

// draw all children
//for (unsigned int n = 0; n < nd->mNumChildren; ++n)
//{
// recursive_render( nd->mChildren[n]);
//}





glPopMatrix( );


I'm having some problems as they seem to be so many examples with so slightly different ways of doing things.
Thanks in advance!

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Hardcode a mesh first maybe:

Mesh m;
m.mNumVertices =3;
m.mVertices[0] = something


So make a triangle and see if that works first.

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Are you sure you have a single GL_TRIANGLE_STRIP? Sound like you have GL_TRIANGLES because you have the value of 3.

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