Can Render Triangle And A Quad, But More Complex Shape Results In Segfault

Mathias Soeholm · 2016-08-09T09:48:11

Hello there! I am currently making my own little game engine with OpenGL, but I have been stuck with this problem for a while now. I can render a triangle with no problems, but I get a segfault from glDrawElements with a more complex shape. I'll try and post the relevant code snippets. Here is how I send mesh data to the buffer: void Mesh::sendToBuffer() { GLuint vbo = 0; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, verticesBufferSize(), vertices, GL_STATIC_DRAW); GLuint ibo; glGenBuffers(1, &ibo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, indicesBufferSize(), indices, GL_STATIC_DRAW); vao = 0; glGenVertexArrays(1, &vao); glBindVertexArray(vao); glEnableVertexAttribArray(0); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo); // Position glVertexAttribPointer(0, numVertices, GL_FLOAT, GL_FALSE, sizeof(Vertex), nullptr); // Normals glVertexAttribPointer(1, numVertices, GL_FLOAT, GL_FALSE, sizeof(Vertex), (const void *)3); } Here is the code for creating a triangle, this works flawlessly: Mesh Primitives::createTriangle() { Mesh tri; tri.numVertices = 3; Vertex vertices[] = { glm::vec3(0.0f, 0.5f, 0.0f), // Position glm::vec3(0.0f, 0.0f, 1.0f), // Normal glm::vec3(1.0f, 1.0f, 1.0f), // Color glm::vec3(0.5f, -0.5f, 0.0f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(1.0f, 1.0f, 1.0f), glm::vec3(-0.5f, -0.5f, 0.0f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(1.0f, 1.0f, 1.0f) }; tri.vertices = new Vertex[tri.numVertices]; memcpy(tri.vertices, vertices, sizeof(vertices)); tri.numIndices = 3; GLushort indices[] = { 0, 1, 2 }; tri.indices = new GLushort[tri.numIndices]; memcpy(tri.indices, indices, sizeof(indices)); tri.sendToBuffer(); return tri; } However rendering a cube, or part of a cube as shown here, fails: Mesh Primitives::createCube() { Mesh cube; cube.numVertices = 6; Vertex vertices[] = { glm::vec3(-0.5f, -0.5f, 0.5f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(5.0f, 5.0f, 5.0f), glm::vec3(-0.5f, 0.5f, 0.5f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(5.0f, 5.0f, 5.0f), glm::vec3(0.5f, 0.5f, 0.5f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(5.0f, 5.0f, 5.0f), glm::vec3(-2.5f, -0.5f, 0.5f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(5.0f, 5.0f, 5.0f), glm::vec3(-2.5f, 0.5f, 0.5f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(5.0f, 5.0f, 5.0f), glm::vec3(-1.0f, 0.5f, 0.5f), glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(5.0f, 5.0f, 5.0f), }; cube.vertices = new Vertex[cube.numVertices]; memcpy(cube.vertices, vertices, sizeof(vertices)); cube.numIndices = 6; GLushort indices[] = { 0, 1, 2, 0, 1, 2 // Front //4, 5, 6, 6, 7, 4, // Back //8, 9, 10, 10, 11, 8, // Bottom //12, 13, 14, 14, 15, 12, // Top //16, 17, 18, 18, 19, 16, // Left //20, 21, 22, 22, 23, 20 // Right }; cube.indices = new GLushort[cube.numIndices]; memcpy(cube.indices, indices, sizeof(indices)); cube.sendToBuffer(); return cube; } And to draw the mesh I simply call: mesh.bind(); glDrawElements(GL_TRIANGLES, mesh.getNumIndices(), GL_UNSIGNED_SHORT, 0); I think this is the relevant code, the full source is on GitHub: https://github.com/mathiassoeholm/OpenGLPlayground/tree/master/GameEngine I'm sorry for posting so much code here, but I'm at a loss for what causes the Segmentation fault to happen. Any help is much appreciated.