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POProgrammatically Generate OpenGL Vertex Data in iOS
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  1. POProgrammatically Generate OpenGL Vertex Data in iOS
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    copied!<p>Basically what I want to do is generate my vertex coordinates programmatically instead of storing it in a statically predefined array. Unfortunately I am not able to convert a very simple example to a dynamic array.</p> <p>Everything works fine if I stick to static arrays:</p> <pre><code>typedef struct { GLfloat Position[3]; GLfloat Color[4]; GLfloat TexCoord[2]; float Normal[3]; } Vertex; Vertex sphereVertices[] = { {{1, -1, 1}, {1, 0, 0, 1}, {1, 0}, {0, 0, 1}}, {{1, 1, 1}, {0, 1, 0, 1}, {1, 1}, {0, 0, 1}}, {{-1, 1, 1}, {0, 0, 1, 1}, {0, 1}, {0, 0, 1}}, {{-1, -1, 1}, {0, 0, 0, 1}, {0, 0}, {0, 0, 1}} }; GLubyte sphereIndices [] = { 0, 1, 2, 2, 3, 0 }; </code></pre> <p>...</p> <pre><code>glGenBuffers(1, &amp;sphereIndexBuffer); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, sphereIndexBuffer); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(sphereIndices), sphereIndices, GL_STATIC_DRAW); glEnableVertexAttribArray(GLKVertexAttribPosition); glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (const GLvoid *) offsetof(Vertex, Position)); </code></pre> <p>...</p> <pre><code>glDrawElements(GL_TRIANGLES, 6 * sizeof(GLubyte), GL_UNSIGNED_BYTE, 0); </code></pre> <p>As soon as I switch my indices to a dynamic array only the first triangle shows up.</p> <pre><code>GLubyte *sphereIndices; +(void)initialize { sphereIndices = malloc(6 * sizeof(GLubyte)); sphereIndices[0] = 0; sphereIndices[1] = 1; sphereIndices[2] = 2; sphereIndices[3] = 2; sphereIndices[4] = 3; sphereIndices[5] = 0; } </code></pre> <p>Probably this has something to do with pointers. Does anybody know what I am doing wrong? </p> <p>Thanks!</p>
 

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