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POOpenGL buffer update
 

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  1. POOpenGL buffer update
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    <p>Currently I'm writing a program that simulates water. Here are the steps that I do:</p> <ol> <li>Create water surface - plane.</li> <li>Create VAO</li> <li>Create vertex buffer object in which I store normals and vertices.</li> <li>Bind pointers to this VBO.</li> <li>Create index buffer object.</li> </ol> <p>Then I render this plane using glDrawElements and then I invoke an update() function which changes positions of vertices of water surface. After that I invoke glBufferSubData function to update vertices positions.</p> <p>When I do that - nothing happens as if the buffer isn't changed.</p> <p>Here's the code snippet:</p> <pre><code>glGenBuffers(1, &amp;vertexBuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer); glBufferData(GL_ARRAY_BUFFER, sizeof(Oscillator) * nOscillators, oscillators, GL_DYNAMIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Oscillator), 0); glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(Oscillator), (const GLvoid*)12); glEnableVertexAttribArray(0); // Vertex position glEnableVertexAttribArray(2); // normals position glGenBuffers(1, &amp;indicesBuffer); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indicesBuffer); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * nIndices, indices, GL_DYNAMIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indicesBuffer); glBindVertexArray(0); </code></pre> <p>Then render:</p> <pre><code>glBindVertexArray(vaoHandle); glDrawElements(GL_TRIANGLES, nIndices, GL_UNSIGNED_INT, 0); update(time); </code></pre> <p>And update function:</p> <pre><code>//some calculations glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(Oscillator) * nOscillators, oscillators); </code></pre> <p><b><i>Oscillator</i></b> - it's a structure that has: 8 floats respectively - x, y, z (vertex position), nx, ny, nz (normals), upSpeed, newY</p> <p><b><i>oscillators</i></b> - this is an array of Oscillator structures.</p> <p>What I do wrong?</p>
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    1. USShot
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      1. VTUpMod
    1. CODoes the water render correctly before you call update?
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      1. USAndreas Brinck
    2. CODo you clear the color buffer/depth buffer/... before you call draw again?
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      1. USFelics
    3. COYes, water renders correctly and I clear color and depth buffers.
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      1. USShot
 

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