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POApplying textures to a vertex buffer object primitive
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  1. POApplying textures to a vertex buffer object primitive
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    copied!<p>How do you apply textures to a vertex buffer object in Android?</p> <p><strong>ANSWER:</strong> </p> <hr> <p>The code works fine, except it is missing a call to</p> <pre><code>glEnable(GL_TEXTURE_2D); </code></pre> <p>This and the call of</p> <pre><code>glEnableClientState(GL_TEXTURE_COORD_ARRAY); </code></pre> <p>are both required for in order for vertex buffer object to draw texture.</p> <hr> <p><strong>QUESTION:</strong></p> <p>From what I know, first you must create a NIO Buffer:</p> <pre><code>ByteBuffer tbb = ByteBuffer.allocateDirect(texCoords.length * 4); tbb.order(ByteOrder.nativeOrder()); FloatBuffer textureBuffer = tbb.asFloatBuffer(); textureBuffer.put(texCoords); textureBuffer.position(0); </code></pre> <p>In this code sample, the array <em>texCoords</em> contains the 2-component (s, t) texture data.</p> <p>After creating the NIO Buffer, you need to pass it to opengl and create Vertex Buffer Object:</p> <pre><code>int[] id = new int[1];//stores the generated ID. gl11.glGenBuffers(1, id, 0); gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, id[0]); gl11.glBufferData(GL11.GL_ARRAY_BUFFER, texCoords.length * 4, textureBuffer, GL11.GL_STATIC_DRAW); </code></pre> <p>So that takes care of all the initalization. Next we need to draw it, and we do so like this:</p> <pre><code>gl11.glEnableClientState(GL11.GL_TEXTURE_COORD_ARRAY);//enable for textures gl11.glActiveTexture(GL11.GL_TEXTURE0); //lets pretend we created our texture elsewheres and we have an ID to represent it. gl11.glBindTexture(GL11.GL_TEXTURE_2D, textureId); //Now we bind the VBO and point to the buffer. gl11.glBindBuffer(GL11.GL_ARRAY_BUFFER, id[0])//the id generated earlier. gl11.glTexCoordPointer(2, GL11.GL_FLOAT, 0, 0);//this points to the bound buffer //Lets also pretend we have our Vertex and Index buffers specified. //and they are bound/drawn correctly. </code></pre> <p>So even though this is what I would think would be needed in order for OpenGL to draw the texture, I have an error, and only a red triangle (without my modulated stone texture) renders.</p>
 

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