vertex-buffer

问题 Would someone care to explain the difference to be between a VertexBuffer , a VertexArray , a VertexBufferObject , and a VertexArrayObject ? I'm not even sure if these are all terms for different things, but I've seen all of them appear in the OpenGL spec. I know that a VertexBuffer simply contains vertices and nothing else, once bound, and once I've set the vertex pointers, I can use DrawArrays to draw it. I've done it this way many times. I am using what I think is a VertexArray, which

来源： https://stackoverflow.com/questions/15672720/pyopengl-dynamically-updating-values-in-a-vertex-buffer-object

来源： https://stackoverflow.com/questions/15672720/pyopengl-dynamically-updating-values-in-a-vertex-buffer-object

问题 I am struggling to understand how exactly VAO is handling buffer mapping. What I'm doing could be described in this pseudocode: SetUp: BindVAO BindArrayBuffer glBufferData(GL_ARRAY_BUFFER, ExpectedMaxCount, NULL, GL_DYNAMIC_DRAW);//Allocate storage glEnableVertexAttribArray glVertexAttribPointer BindElementBuffer Allocate storage (no data yet) UnbindVAO UnbindArrayBuffer UnbindElementBuffer Draw: SubArrayAndElementDataIfNeeded BindVAO DrawElements Is this correct that when DrawElements is

问题 I am struggling to understand how exactly VAO is handling buffer mapping. What I'm doing could be described in this pseudocode: SetUp: BindVAO BindArrayBuffer glBufferData(GL_ARRAY_BUFFER, ExpectedMaxCount, NULL, GL_DYNAMIC_DRAW);//Allocate storage glEnableVertexAttribArray glVertexAttribPointer BindElementBuffer Allocate storage (no data yet) UnbindVAO UnbindArrayBuffer UnbindElementBuffer Draw: SubArrayAndElementDataIfNeeded BindVAO DrawElements Is this correct that when DrawElements is

问题 I have OpenGL rendering code calling glDrawArrays that works flawlessly when the OpenGL context is (automatically / implicitly obtained) 4.2 but fails consistently (GL_INVALID_OPERATION) with an explicitly requested OpenGL core context 3.2. (Shaders are always set to #version 150 in both cases but that's beside the point here I suspect.) According to specs, there are only two instances when glDrawArrays() fails with GL_INVALID_OPERATION: "if a non-zero buffer object name is bound to an

问题 I want to send a buffer list (to the GPU/vertex shader) which contains information about vertex position, world position, color, scale, and rotation. If each of my 3D objects have transformation related information in a matrix, how can i pass this array of matrices (in addition to the other vertex data) to the GPU via the VBO(s) ? Updated Please excuse any typos: // bind & set vertices. gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer); gl.vertexAtribPointer(a_Position, 3, gl.FLOAT, false, stride,

问题 I'm using Direct3D 9 to draw lines. The vertices I am using now have the format D3DFVF_XYZ|D3DFVF_DIFFUSE and are stored in a vertex buffer. They are drawn with DrawPrimitive as D3DPT_LINELIST . How do I change the drawn color of a the whole drawn vertex buffer or even a specific vertex without locking the vertex buffer to modify it's content? This has to be done every frame. Is this possible with a vertex buffer? I would prefer a solution without a custom shader (using the default direct3d 9

问题 I'm working on a multithreaded app that simultaneously renders geometry to multiple FBOs. I'm experiencing a leak (as described on this question). I've been able to narrow it down a little — if I make one change, it stops leaking — but I can't figure out why. On each of 4 threads (each with its own shared context), I'm doing the following each render cycle: // Upload positionBuffer = getUnusedArrayBufferFromPool(); glBindBuffer(GL_ARRAY_BUFFER, positionBuffer); glBufferData(GL_ARRAY_BUFFER,

问题 For the other buffers there are functions like: glVertexArrayVertexAttribOffsetEXT( this->handle, // vao handle vbo.getHandle(), // vbo handle index, // specifies the index of the generic vertex attribute to be modified. size, // number of components per generic vertex attribute vbo.getType(), // specifies the data type of each component in the array normalized, // specifies whether fixed-point data values should be normalized stride, // specifies the byte offset between consecutive generic