/**
* A utility method to load vertex data into an OpenGL "vertex array object" (VAO) for efficient
* rendering. The VAO stores several "vertex buffer objects" (VBOs) that contain the vertex
* attribute data.
*
* @param data reference to the vertex data to be loaded into a VAO
*/
private void initArrayBuffer(GLVertexData data) {
// Make a vertex array object (VAO) for this vertex data
// and store a reference to it
GLVertexArrayObject vao = new GLVertexArrayObject(gl, data.getElements().size() + 1);
data.setVAO(vao);
// Bind (activate) the VAO for the vertex data in OpenGL.
// The subsequent OpenGL operations on VBOs will be recorded (stored)
// in the VAO.
vao.bind();
// Store all vertex attributes in vertex buffer objects (VBOs)
ListIterator<VertexData.VertexElement> itr = data.getElements().listIterator(0);
data.getVAO().rewindVBO();
while (itr.hasNext()) {
VertexData.VertexElement e = itr.next();
// Bind the vertex buffer object (VBO)
gl.glBindBuffer(GL3.GL_ARRAY_BUFFER, data.getVAO().getNextVBO());
// Upload vertex data
gl.glBufferData(
GL3.GL_ARRAY_BUFFER,
e.getData().length * 4,
FloatBuffer.wrap(e.getData()),
GL3.GL_DYNAMIC_DRAW);
}
// Bind the default vertex buffer objects
gl.glBindBuffer(GL3.GL_ARRAY_BUFFER, 0);
// Store the vertex data indices into the last vertex buffer
gl.glBindBuffer(GL3.GL_ELEMENT_ARRAY_BUFFER, data.getVAO().getNextVBO());
gl.glBufferData(
GL3.GL_ELEMENT_ARRAY_BUFFER,
data.getIndices().length * 4,
IntBuffer.wrap(data.getIndices()),
GL3.GL_DYNAMIC_DRAW);
// Bind the default vertex array object. This "deactivates" the VAO
// of the vertex data
gl.glBindVertexArray(0);
}
