I've been trying to use Vertex Buffer Objects to save vertex data on the GPU and reduce the overhead, but I cannot get it to work. The code is below.
From what I understand you generate the buffer with glGenBuffers
, then you bind the buffer with glBindBuffer
so it's ready to be used, then you write data to it with glBufferData
and its done and can be unbinded and ready for use later with simply binding it again.
However the last part is what I'm having trouble with, when I bind it after I have created and loaded data to it and try to draw using it, it gives me lots of GL Error: Out of Memory.
I doubt that I am running out of memory for my simple mesh, so I must be doing something very wrong.
Thanks.
EDIT 1: I call glGetError after every frame, but since this is the only OpenGL I do in the entire program it shouldn't be a problem
//when loading the mesh we create the VBO
void createBuffer()
{
GLuint buf;
glGenBuffers(1, &buf);
glBindBuffer(GL_ARRAY_BUFFER, buf);
glBufferData(GL_ARRAY_BUFFER, vertNormalBuffer->size() * sizeof(GLfloat), (GLvoid*) bufferData, GL_STATIC_DRAW);
//EDIT 1: forgot to show how I handle the buffer
model->vertexNormalBuffer = &buf;
//Unbinds it
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
void Fighter::doRedraw(GLuint shaderProgram)
{
glm::mat4 transformationMatrix = getTransform();
GLuint loc = glGetUniformLocation(shaderProgram,"modelviewMatrix");
glUniformMatrix4fv(loc, 1, GL_FALSE, (GLfloat*) &transformationMatrix);
glBindBuffer(GL_ARRAY_BUFFER, *model->vertexNormalBuffer);
//If I uncomment this line below all works wonderfully, but isnt the purpose of VBO of not uploading the same data again and again?
//glBufferData(GL_ARRAY_BUFFER, model->vertAndNormalArraySize * sizeof(GLfloat), model->vertAndNormalArray, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(2);
renderChild(model, model);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
void Fighter::renderChild(ModelObject* model, ModelObject* parent)
{
//Recursively render the mesh children
for(int i = 0; i < model->nChildren; i++)
{
renderChild( dynamic_cast<ModelObject*>(model->children[i]), parent);
}
//Vertex and normal data are interlieved
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 8*sizeof(GLfloat),(void*)(model- >vertexDataPosition*sizeof(GLfloat)));
glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, 8*sizeof(GLfloat), (void*)((model->vertexDataPosition + 4)*sizeof(GLfloat)));
//Draws using two sets of indices
glDrawElements(GL_QUADS, model->nQuads * 4, GL_UNSIGNED_INT,(void*) model->quadsIndices);
glDrawElements(GL_TRIANGLES, model->nTriangles * 3, GL_UNSIGNED_INT, (void*) model->trisIndices);
}