glDrawArrays segmentation fault - c++

Question

I am trying to render a simple triangle with OpenGL 3.3, but when I call glDrawArrays my program crashes with a segmentation fault. The language I'm using is C++ and I use the libraries SDL, glew and glm.
I think what happens is, that the draw call tries to access data that doesn't belong to the vertex buffer I have set up.
For reasons that don't really matter I can not provide the whole source code of my program. However I can provide some relevant snippets and a trace of the OpenGL calls issued, generated with the tool Apitrace.
[...]
glClearColor(red = 0, green = 0, blue = 0.5, alpha = 1)
glClear(mask = COLOR_BUFFER_BIT)
glGenVertexArrays(n = 1, arrays = &1)
glBindVertexArray(array = 1)
glGenBuffers(n = 1, buffer = &1)
glBindBuffer(target = GL_ARRAY_BUFFER, buffer = 1)
glBufferData(target = GL_ARRAY_BUFFER, size = 72, data = blob(72), usage = GL_STATIC_DRAW)
glVertexAttribPointer(index = 0, size = 3, type = GL_FLOAT, normalized = GL_FALSE, stride = 24, pointer = NULL)
glVertexAttribPointer(index = 1, size = 3, type = GL_FLOAT, normalized = GL_FALSE, stride = 24, pointer = 0xc)
glEnableVertexAttribArray(index = 0)
glEnableVertexAttribArray(index = 1)
glCreateShader(type = GL_VERTEX_SHADER) = 1
glShaderSource(shader = 1, count = 1, string = &"#version 330
layout (location = 0) in vec3 iPosition;
layout (location = 1) in vec3 iNormal;
void main() {
gl_Position = vec4(iPosition.x, iPosition.y, iPosition.z, iNormal.z * -1.0);
}", length = NULL)
glCreateShader(type = GL_FRAGMENT_SHADER) = 2
glShaderSource(shader = 2, count = 1, string = &"#version 330
out vec4 oFragColor;
void main() {
oFragColor = vec4(1.0, 0.0, 0.0, 1.0);
}", length = NULL)
glCompileShader(shader = 1)
glGetShaderiv(shader = 1, pname = GL_COMPILE_STATUS, params = &1)
glCompileShader(shader = 2)
glGetShaderiv(shader = 2, pname = GL_COMPILE_STATUS, params = &1)
glCreateProgram() = 3
glAttachShader(program = 3, shader = 1)
glAttachShader(program = 3, shader = 2)
glBindAttribLocation(program = 3, index = 1, name = "iNormal")
glBindAttribLocation(program = 3, index = 0, name = "iPosition")
glLinkProgram(program = 3)
glGetProgramiv(program = 3, pname = GL_LINK_STATUS, params = &1)
glGetAttribLocation(program = 3, name = "iPosition") = 0
glGetAttribLocation(program = 3, name = "iNormal") = 1
glGetIntegerv(pname = GL_CURRENT_PROGRAM, params = &0)
glUseProgram(program = 3)
glBindVertexArray(array = 1)
glClear(mask = GL_COLOR_BUFFER_BIT)
glDrawArrays(mode = GL_TRIANGLES, first = 0, count = 3) //incomplete (segfault here)
As I said, I think the problem is, that the draw call tries to access data in a wrong way. I have already checked the data in the vertex buffer using glGetBufferSubData. So here is the Code i use to set up the VAO:
Mesh::Mesh(const std::vector<Triangle>& triangles): _vao(0), _vbo(0) {
glGenVertexArrays(1, &_vao);
glBindVertexArray(_vao);
glGenBuffers(1, &_vbo);
glBindBuffer(GL_ARRAY_BUFFER, _vbo);
struct Vertex {
glm::vec3 position;
glm::vec3 normal;
}
Vertex* vertecies = new Vertex[triangles.size() * 3];
// [...]
// Convert triangles to vertecies, store them in the array.
glBufferData(GL_ARRAY_BUFFER, triangles.size() * 3 * sizeof(Vertex), vertecies, GL_STATIC_DRAW);
delete[] vertecies;
//Position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), reinterpret_cast<void*>(0));
//Normal
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), reinterpret_cast<void*>(3 * sizeof(GL_FLOAT)));
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
}
I suspect the error to be in the way I call glVertexAttribPointer.
If other parts of the program are necessary to answer, leave me a comment and I'll see what I can do to provide them.

Answer 1

I dont see anything wrong with your code. I usually get this problem when my context isnt set correctly. For example, when I dont have GLEW set up correctly in my case. That may be the same problem for you.