Running a very simple draw a triangle example, I'm trying to find out which lines refer specifically to the VAO definition and which others can run apart.
Currently I'm using this code:
Buffer creation & filling:
TriangleVertices = new float[9]
{
0.0f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
};
TriangleColors = new float[12]
{
1.0f, 0.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
};
glGenBuffers(1, &VertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, VertexBuffer);
glBufferData(GL_ARRAY_BUFFER, 9*sizeof(float), TriangleVertices, GL_STATIC_DRAW);
glGenBuffers(1, &ColorsBuffer);
glBindBuffer(GL_ARRAY_BUFFER, ColorsBuffer);
glBufferData(GL_ARRAY_BUFFER, 12*sizeof(float), TriangleColors, GL_STATIC_DRAW);
glGenVertexArrays(1, &VAOID);
VAO definition:
glBindVertexArray(VAOID);
glBindBuffer(GL_ARRAY_BUFFER, VertexBuffer);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glBindBuffer(GL_ARRAY_BUFFER, ColorsBuffer);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(0);
glBindVertexArray(0);
Drawing Loop
glBindVertexArray(VAOID);
glDrawArrays(GL_TRIANGLES, 0, 3);
glBindVertexArray(0);
The example runs fine if in the drawing loop I include the VAO definition each frame, but it doesn't work if I define the VAO only once before starting to draw so I guess the VAO definition lacks some code.
What am I missing?
EDIT: The code in the question was correct. The problem was coming from collision with other OpenGL calls I thought I wasn't running.
The code described below is just situational. As @derhass commented, there is no need to enable nor disable VertexAttribArray when making the draw call.
...
Old answer:
Unbindinding and disabling each element when not needed anymore fixed the problem, but I don't know if this solution can be widespread or it is specific to my environment only.
Buffer creation & filling:
TriangleVertices = new float[9]
{
0.0f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
};
TriangleColors = new float[12]
{
1.0f, 0.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
};
glGenBuffers(1, &VertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, VertexBuffer);
glBufferData(GL_ARRAY_BUFFER, 9*sizeof(float), TriangleVertices, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glGenBuffers(1, &ColorsBuffer);
glBindBuffer(GL_ARRAY_BUFFER, ColorsBuffer);
glBufferData(GL_ARRAY_BUFFER, 12*sizeof(float), TriangleColors, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glGenVertexArrays(1, &VAOID);
VAO definition:
glBindVertexArray(VAOID);
glBindBuffer(GL_ARRAY_BUFFER, VertexBuffer);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ARRAY_BUFFER, ColorsBuffer);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glEnableVertexAttribArray(0);
glBindVertexArray(0);
Drawing Loop
glBindVertexArray(VAOID);
glEnableVertexAttribArray(0);//not needed
glEnableVertexAttribArray(1);//not needed
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);//not needed
glDisableVertexAttribArray(1);//not needed
glBindVertexArray(0);
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