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.obj file loader


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#1 sothro   Members   -  Reputation: 139

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Posted 22 January 2014 - 01:42 PM

hi,

 

I'm having a problem with showing a model that i have loaded from a object file, the vertexes and indices are loaded oke in to 2 vectors in a seperate class. Below you see my creat methode i have set the lines in bold that have changed for drawing the loaded object in place of a hardcoded one. I think the problem lays with one of these lines. Also i have added my model class as a file.

Thank you for all the helpsmile.png

ShaderIds[1] = LoadShader("\\Debug\\SimpleShader.fragment.glsl", GL_FRAGMENT_SHADER);
    ShaderIds[2] = LoadShader("Debug\\SimpleShader.vertex.glsl", GL_VERTEX_SHADER);
    
    ShaderIds[0] = glCreateProgram();
    ExitOnGLError("ERROR: Could not create the shader program");
    
    glAttachShader(ShaderIds[0], ShaderIds[1]);
    glAttachShader(ShaderIds[0], ShaderIds[2]);

    glLinkProgram(ShaderIds[0]);
    ExitOnGLError("ERROR: Could not link the shader program");

    ModelMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ModelMatrix");
    ExitOnGLError("ERROR: Could not get the shader uniform locations for modelmatrix");
    ViewMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ViewMatrix");
    ExitOnGLError("ERROR: Could not get the shader uniform locations for viewmatrix");
    ProjectionMatrixUniformLocation = glGetUniformLocation(ShaderIds[0], "ProjectionMatrix");
    ExitOnGLError("ERROR: Could not get the shader uniform locations for projectionMatrix");

    glGenVertexArrays(1, &BufferIds[0]);
    ExitOnGLError("ERROR: Could not generate the VAO");
    glBindVertexArray(BufferIds[0]);
    ExitOnGLError("ERROR: Could not bind the VAO");

    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);
    ExitOnGLError("ERROR: Could not enable vertex attributes");

    glGenBuffers(2, &BufferIds[1]);
    ExitOnGLError("ERROR: Could not generate the buffer objects");


    glBindBuffer(GL_ARRAY_BUFFER, BufferIds[1]);
    //glBufferData(GL_ARRAY_BUFFER, sizeof(VERTICES), VERTICES, GL_STATIC_DRAW);
    glBufferData(GL_ARRAY_BUFFER, 256/*sizeof((*model).GetVertices().size())*/, &(*model).GetVertices(), GL_STATIC_DRAW);

    ExitOnGLError("ERROR: Could not bind the VBO to the VAO");


    //glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)0);
    //glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)sizeof(VERTICES[0].Position));
        glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof((*model).GetVertices()[0]), (GLvoid*)0);
    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof((*model).GetVertices()[0]), (GLvoid*)sizeof(&(*model).GetVertices()[0].Position));
    ExitOnGLError("ERROR: Could not set VAO attributes");

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, BufferIds[2]);
    //glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(INDICES), INDICES, GL_STATIC_DRAW);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 144/*sizeof((*model).GetIndices().size())*/, &(*model).GetIndices(), GL_STATIC_DRAW);

    ExitOnGLError("ERROR: Could not bind the IBO to the VAO");
 
    glBindVertexArray(0);

Attached Files


Edited by sothro, 22 January 2014 - 03:05 PM.


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#2 BitMaster   Crossbones+   -  Reputation: 3001

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Posted 22 January 2014 - 03:27 PM

Since you did not post the code of the loader, the standard question has to be asked: did you compensate for the fact that .obj file indices are 1-based?

 

If that is not the problem, what is the actual problem? What do you expect to happen? What happens?



#3 sothro   Members   -  Reputation: 139

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Posted 22 January 2014 - 04:20 PM

I compensated the fact that indices are 1-based and i can see the model now on the screen because i have changed the code to this:

    glBindBuffer(GL_ARRAY_BUFFER, BufferIds[1]);
    //glBufferData(GL_ARRAY_BUFFER, sizeof(VERTICES), VERTICES, GL_STATIC_DRAW);
    glBufferData(GL_ARRAY_BUFFER, 256/*sizeof((*model).GetVertices().size())*/, &(*model).GetVertices()[0], GL_STATIC_DRAW);

    ExitOnGLError("ERROR: Could not bind the VBO to the VAO");

    //glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)0);
    //glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(VERTICES[0]), (GLvoid*)sizeof(VERTICES[0].Position));
        glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof((*model).GetVertices()[0]), (GLvoid*)0);
    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof((*model).GetVertices()[0]), (GLvoid*)sizeof((*model).GetVertices()[0].Position));
    ExitOnGLError("ERROR: Could not set VAO attributes");


    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, BufferIds[2]);
    //glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(INDICES), INDICES, GL_STATIC_DRAW);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 144/*sizeof((*model).GetIndices().size())*/, &(*model).GetIndices()[0], GL_STATIC_DRAW);

but the numbers 256 and 144 need to be dynamic i need to get the size off the memory used by the array i think, but when i use the sizeof i only get the size of the pointer.

I think i need to calculate how mutch space is used but don't know how exactly.

Thanks for the help so far smile.png


Edited by sothro, 22 January 2014 - 04:22 PM.


#4 sothro   Members   -  Reputation: 139

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Posted 22 January 2014 - 04:49 PM

Hi i have found a way to calculate the values, but i was wondering if their is a better way.

My calculation is as follow:

 

For the vertexes

int sizeVertex=sizeof((*model).GetVertices()[0]);
    int vertexEllements=(*model).GetVertices().size();
    int sizeVertexes=sizeVertex*vertexEllements;

For the Indices

nt size=sizeof((*model).GetIndices()[0]);
    int ellements=(*model).GetIndices().size();
    int sizeIndices=size*ellements;

If anybody knows a better way do tell.

Or if you have other suggestions to improve the code i'm all ears biggrin.png



#5 Ectara   Crossbones+   -  Reputation: 2402

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Posted 22 January 2014 - 10:05 PM


sizeof((*model).GetIndices().size())

I am quite sure that this will not do what you think it is doing. If this is a standard container, you are passing sizeof(std::size_t). Perhaps you just want to use (*model).GetIndices().size()? (Times the size of each element, if you are going for a total byte count?)

 

 

 


If anybody knows a better way do tell.

If you find the size of each element, and you find the number of elements, then you'll arrive at this algorithm, as you did. It should be fine; there are faster ways, but most aren't recommended for reasons of readability. On a side note, if this is an std::vector, you can use (*model).GetIndices().front() instead of indexing it with zero.


Edited by Ectara, 22 January 2014 - 10:23 PM.


#6 sothro   Members   -  Reputation: 139

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Posted 22 January 2014 - 11:50 PM

Thanks for the tip Ectara wink.png



#7 apatriarca   Crossbones+   -  Reputation: 1475

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Posted 23 January 2014 - 03:30 AM

Is there any reason you are using (*model).GetIndices() instead of model->GetIndices() ? 



#8 sothro   Members   -  Reputation: 139

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Posted 23 January 2014 - 11:57 AM

No not really. Is it better to use -> or is it nicer to read just?

Thanks for all the tips :D



#9 richardurich   Members   -  Reputation: 1161

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Posted 23 January 2014 - 07:34 PM

No not really. Is it better to use -> or is it nicer to read just?

Thanks for all the tips biggrin.png

Think of "->" as reading "points to" and whenever that sounds right, it's probably good to use "->". As the first responses in the thread demonstrate though, it's not hard to read in any case. You can also use var[0].Foo() instead of (*var).Foo() if it makes sense. Whatever you do, just be consistent. It's easy to mentally adjust to someone else's style as long as it is consistent.






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