This code works fine.
glGenVertexArrays(1, &m_VAO);
glGenBuffers(1, &m_VBO);
glGenBuffers(1, &m_EBO);
glBindVertexArray(m_VAO);
glBindBuffer(GL_ARRAY_BUFFER, m_VBO);
glBufferData(GL_ARRAY_BUFFER, data.size() * sizeof(VertexFormat), &data[0] , GL_DYNAMIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GL_UNSIGNED_INT), &indices[0], GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(VertexFormat), (void*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(VertexFormat), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(VertexFormat), (void*)(6 * sizeof(float)));
glBindVertexArray(0);
But when i try to change it to DSA nothing gets drawn on the screen.
glCreateBuffers(1, &m_VBO);
glNamedBufferStorage(m_VBO, data.size() * sizeof(VertexFormat), &data[0], GL_DYNAMIC_STORAGE_BIT);
glCreateBuffers(1, &m_EBO);
glNamedBufferStorage(m_EBO, indices.size() * sizeof(unsigned int), &indices[0], GL_DYNAMIC_STORAGE_BIT);
glCreateVertexArrays(1, &m_VAO);
glVertexArrayVertexBuffer(m_VAO, 0, m_VBO, 0, data.size() * sizeof(VertexFormat));
glVertexArrayElementBuffer(m_VAO, m_EBO);
glEnableVertexArrayAttrib(m_VAO, 0);
glEnableVertexArrayAttrib(m_VAO, 1);
glEnableVertexArrayAttrib(m_VAO, 2);
glVertexArrayAttribFormat(m_VAO, 0, 3 , GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(m_VAO, 1, 3 , GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(m_VAO, 2, 2 , GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribBinding(m_VAO, 0, 0);
glVertexArrayAttribBinding(m_VAO, 1, 0);
glVertexArrayAttribBinding(m_VAO, 2, 0);
What is the issue in the DSA section of code?
You did not transfer over two pieces of information.
You didn't specify the stride in glVertexArrayVertexBuffer correctly. When using separate attribute format, a stride of 0 doesn't mean "tightly packed"; it means exactly what it says: zero bytes will be added to get the next array element.
You also didn't specify the offsets for each attribute in glVertexArrayAttribFormat the way you did with glVertexAttribPointer.
Related
I was working on an OpenGL project where I tried to use DSA concepts instead of binding the variables. One way that I use this is when creating a VBO, VAO, and EBO for a set of meshes from a model that I loaded. The code runs fine on my own executable after compiling and linking everything.
I've tried to add other unrelated functionality, but I need to debug it through RenderDoc. The problem is that nothing shows on screen when I run the executable through it.
I saw that one of the reasons why is because it doesn't see the VBO that I create for each mesh and shows it as Unkown Resource #.
I changed the DSA code that creates these buffers to do it the normal way, and it actually works when I do it that way. I'm confused if there is a bug with my code in terms of the way I do the calls, or if it's something else like a driver issue that I can't really fix by myself. For reference, I have a RX 6700 XT in case someone else has gone through the same issue.
For reference the DSA Way:
GLuint binding_index = 0;
glCreateVertexArrays(1, &mesh.VAO);
glCreateBuffers(1, &mesh.EBO);
glCreateBuffers(1, &mesh.VBO);
glNamedBufferStorage(mesh.VBO, sizeof(Vertex) * mesh.vertices.size(), mesh.vertices.data(), GL_DYNAMIC_STORAGE_BIT);
glNamedBufferStorage(mesh.EBO, mesh.indices.size() * sizeof(unsigned int), mesh.indices.data(), GL_DYNAMIC_STORAGE_BIT);
glVertexArrayVertexBuffer(mesh.VAO, binding_index, mesh.VBO, 0, sizeof(Vertex));
glVertexArrayElementBuffer(mesh.VAO, mesh.EBO);
glEnableVertexArrayAttrib(mesh.VAO, 0);
glEnableVertexArrayAttrib(mesh.VAO, 1);
glEnableVertexArrayAttrib(mesh.VAO, 2);
glEnableVertexArrayAttrib(mesh.VAO, 3);
glEnableVertexArrayAttrib(mesh.VAO, 4);
glVertexArrayAttribFormat(mesh.VAO, 0, 3, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(mesh.VAO, 1, 3, GL_FLOAT, GL_FALSE, offsetof(Vertex, Normal));
glVertexArrayAttribFormat(mesh.VAO, 2, 2, GL_FLOAT, GL_FALSE, offsetof(Vertex, TexCoords));
glVertexArrayAttribFormat(mesh.VAO, 3, 3, GL_FLOAT, GL_FALSE, offsetof(Vertex, Tangent));
glVertexArrayAttribFormat(mesh.VAO, 4, 3, GL_FLOAT, GL_FALSE, offsetof(Vertex, Bitangent));
glVertexArrayAttribBinding(mesh.VAO, 0, binding_index);
glVertexArrayAttribBinding(mesh.VAO, 1, binding_index);
glVertexArrayAttribBinding(mesh.VAO, 2, binding_index);
glVertexArrayAttribBinding(mesh.VAO, 3, binding_index);
glVertexArrayAttribBinding(mesh.VAO, 4, binding_index);
Normal Way:
glGenVertexArrays(1, &mesh.VAO);
glGenBuffers(1, &mesh.VBO);
glGenBuffers(1, &mesh.EBO);
glBindVertexArray(mesh.VAO);
glBindBuffer(GL_ARRAY_BUFFER, mesh.VBO);
glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(Vertex), mesh.vertices.data(), GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mesh.EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned int), mesh.indices.data(), GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*) offsetof(Vertex, Normal));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*) offsetof(Vertex, TexCoords));
// vertex tangent
glEnableVertexAttribArray(3);
glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Tangent));
// vertex bitangent
glEnableVertexAttribArray(4);
glVertexAttribPointer(4, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Bitangent));
I want to draw 2 Vertex Buffers but it only draws the second one. I am using OpenGL 4.6 and the COMPAT profile. The code:
float buffer[] =
{
0.0f,0.0f,
1.0f,0.0f,
1.0f,1.0f
};
float buffera[] =
{
0.0f,0.0f,
1.0f,0.0f,
1.0f,-1.0f
};
unsigned int id;
glGenBuffers(1, &id);
glBindBuffer(GL_ARRAY_BUFFER, id);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), buffer, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
glBindBuffer(GL_ARRAY_BUFFER, 0);
unsigned int ida;
glGenBuffers(1, &ida);
glBindBuffer(GL_ARRAY_BUFFER, ida);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), buffera, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
glBindBuffer(GL_ARRAY_BUFFER, 0);
unsigned int indices[]
{
0,1,2
};
And then the draw calls:
glBindBuffer(GL_ARRAY_BUFFER, id);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
glBindBuffer(GL_ARRAY_BUFFER, ida);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
When glVertexAttribPointer is called, the the buffer which is currently bound to the target ARRAY_BUFFER is associated to the attribute. It is not sufficient to bind the buffer object. You have to do the vertex specification before drawing the object:
glBindBuffer(GL_ARRAY_BUFFER, id);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
glBindBuffer(GL_ARRAY_BUFFER, ida);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
I recommend to use a Vertex Array Object. The VAO is used to store the vertex specification.
unsigned int vao1;
glGenVertexArrays(1, &vao1);
glBindVertexArray(vao1);
unsigned int id;
glGenBuffers(1, &id);
glBindBuffer(GL_ARRAY_BUFFER, id);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), buffer, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
unsigned int vao2;
glGenVertexArrays(1, &vao2);
glBindVertexArray(vao2);
unsigned int ida;
glGenBuffers(1, &ida);
glBindBuffer(GL_ARRAY_BUFFER, ida);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), buffera, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
glBindVertexArray(vao1);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
glBindVertexArray(vao2);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
Since you are not using a VAO, only binding the buffer is not enough. The command which establishes from which buffer a draw command reads is glVertexAttribPointer. You have to move this command into to the draw commands (and since they aren't doing anthing, remove them from the initialization.
The code should be something like:
Init:
unsigned int id;
glGenBuffers(1, &id);
glBindBuffer(GL_ARRAY_BUFFER, id);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), buffer, GL_STATIC_DRAW);
unsigned int ida;
glGenBuffers(1, &ida);
glBindBuffer(GL_ARRAY_BUFFER, ida);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), buffera, GL_STATIC_DRAW);
Drawing:
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, id);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
glBindBuffer(GL_ARRAY_BUFFER, ida);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (const void*)8);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, indices);
I am trying to construct a bar.
First i declare a structure
struct VertexFormat
{
glm::vec3 positions;
glm::vec3 normal;
glm::vec2 texCoord;
VertexFormat(glm::vec3 pos, glm::vec3 norm, glm::vec2 coord) : positions(pos), normal(norm), texCoord(coord)
{ }
};
and than i configure the VAO and the VBO
glBindVertexArray(m_VAO);
glBindBuffer(GL_ARRAY_BUFFER, m_VBO);
glBufferData(GL_ARRAY_BUFFER, data.size() * sizeof(VertexFormat), &data[0], GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size(), &indices[0], GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, data.size() * sizeof(VertexFormat), (void*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, data.size() * sizeof(VertexFormat), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, data.size() * sizeof(VertexFormat), (void*)(6 * sizeof(float)));
glBindVertexArray(0);
Nothing gets drawn when i issue the drawing commands
glBindVertexArray(m_VAO);
glDrawElements(GL_TRIANGLES, 24, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
My question is that am i defining the offsets for the data in the buffer correctly ?
There are several problems with this code:
First, the amount of data uploaded to the EBO is wrong. The size of the data has to be given in byte. Assuming that indices contains unsigned integers, the code should be:
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned int), &indices[0], GL_STATIC_DRAW);
Then, stride describes the offset between two consecutive vertices in the buffer, not the total size of your data. In your case, every vertex starts sizeof(VertexFormat) after the previous one.
The correct code should be:
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(VertexFormat), (void*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(VertexFormat), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(VertexFormat), (void*)(6 * sizeof(float)));
I do want to use an Index Buffer (GL_ELEMENT_ARRAY) together with an Vertex array object. I have the following code:
// Set stuff up
glGenVertexArrays(1, &VertexArrayObjectId);
glBindVertexArray(VertexArrayObjectId);
glGenBuffers( 1, &ArrayBufferId );
glBindBuffer( GL_ARRAY_BUFFER, ArrayBufferId );
glBufferData( GL_ARRAY_BUFFER, sizeof(float) * finalData.size() , finalGPUData, GL_STATIC_DRAW );
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 8, (GLvoid*) 0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_TRUE, sizeof(float) * 8, (GLvoid*) 12);
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 8, (GLvoid*) 20);
glGenBuffers(1, &IndexBufferId);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IndexBufferId);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, finalIndices.size() * sizeof(unsigned int), finalGPUIndices, GL_STATIC_DRAW);
glBindVertexArray(0);
glBindBuffer( GL_ARRAY_BUFFER, 0 );
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
//Render
//Set up shader etc
glBindVertexArray(VertexArrayObjectId);
//glBindBuffer( GL_ARRAY_BUFFER, ArrayBufferId );
//glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 8, (GLvoid*) 0);
//glVertexAttribPointer(1, 2, GL_FLOAT, GL_TRUE, sizeof(float) * 8, (GLvoid*) 12);
//glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 8, (GLvoid*) 20);
glDrawElements(GL_TRIANGLES, finalIndices.size(), GL_UNSIGNED_INT, (void*) 0 );
According to my knowledge, the 4 lines of code, which are commented out are not necessary, because this information is stored in the VAO. (I mean, saving these calls is the purpose of the VAO) However if I run this code it only draws a few Triangles at the origin rather than at the correct vertex position. If I include these lines however, everything gets drawn correctly. So apparently the GL_ELEMENT_ARRAY_BUFFER information is stored correctly within the VAO, but the vertex attributes are not. Is my understanding wrong or are there simply mistakes in my code?
Any help is greatly appreciated.
In my project I'd like to edit given vertex position which is already in GPU.
Do I need to reload whole model or there is an function to change needed vertex.
This is how I pass mesh to GPU
void Mesh3v3n2t::PassToGPU()
{
glGenVertexArrays(1, &VaoId);
glBindVertexArray(VaoId);
glGenBuffers(1, &VboId);
glBindBuffer(GL_ARRAY_BUFFER, VboId);
glBufferData(GL_ARRAY_BUFFER, 32*vertices.size(),vertices.data(), GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 32, 0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 32, (void*)12);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 32, (void*)24);
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glEnableVertexAttribArray(2);
glGenBuffers(1, &IndexBufferId);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IndexBufferId);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size()*4, indices.data(), GL_STATIC_DRAW);
}
You can use glBufferSubData. You may want to rethink the GL_STATIC_DRAW usage hint if you're going to be doing this frequently, but it's not necessary.