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Thread: Transformations on VBOs

  1. #1
    Junior Member
    Join Date
    Jun 2009
    Posts
    2

    Transformations on VBOs

    I'm currently trying to perform transformations on vertex data stored in a VBO. I'm storing vertex data representing multiple meshes in a single VBO, and then attempting to apply separate transformations (glRotatef, glTranslate, etc) between glDrawArray calls. This is not working as expected, in fact, both meshes are simply rendering on top of each other and all the transformations are applying to all the glDrawArray calls. Any guidance on the solution to this would be awesome.
    Code :
    // Bind the buffer object, this is storing mesh 1 and mesh 2 vertex data
    glBindBuffer(GL_ARRAY_BUFFER, mFBO);
     
    // Transform mesh 1
    glRotatef(0.5f, 1.0f, 1.0f, 0.0f);
     
    glColorPointer(4, GL_UNSIGNED_BYTE, 0, 0);
    glVertexPointer(4, GL_FLOAT, 0, mesh1VertexOffset);
     
    // Commit mesh 1 data (0 -> mesh 1 index length)
    glDrawArrays(GL_TRIANGLES, 0, mesh1IndicesLen);
     
    // Transform mesh 2
    glTranslatef(0.002f, 0.0f, 0.0f);
     
    glColorPointer(4, GL_UNSIGNED_BYTE, 0, mesh2ColorOffset);
    glVertexPointer(4, GL_FLOAT, 0, mesh1VertexOffset + mesh2ColorOffset);
     
    // Commit mesh 2 data (mesh 1 index length -> mesh 2 index length)
    glDrawArrays(GL_TRIANGLES, mesh1IndicesLen, mesh2IndicesLen);

  2. #2
    Junior Member
    Join Date
    Jun 2009
    Posts
    2

    Re: Transformations on VBOs [SOLVED]

    Solved the issue. This can be achieved using glPushMatrix() and glPopMatrix(), which I was doing but improperly within the context of VBOs

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