How to convert a glm::vec4<float> to a GLfloat*?
c++, glm-math, opengl
Solution
you can use glm::value_ptr. It works for both `glm::mat` and `glm::vec` and type safe.
Problem
I am trying to pass a `glm::vec4<float>` to `gl::ImmediateMode::glColor4fv(GLfloat*)`: ``` std::vector<glm::vec4> colors; colors.push_back(vec4(1.0f, 0.0f, 0.0f, 1.0f)); glColor4fv(colors[0]); ``` I receive the following error message: ``` error: not matching function call to 'ImmediateMode::glColor4fv(const vec4&) const' [...] candidate is: [...] void gl::ImmediateMode::glColor4fv(GLfloat*) const ``` Clearly I have to convert my glm::vec4 to a GLfloat array. I read through the GLSLanguage Specifications and could not find any way to access the data directly. The following attempt works: ``` GLfloat *c = new GLfloat[4]; c[0] = colors[0].r; c[1] = colors[0].g; c[2] = colors[0].b; c[3] = colors[0].a; glColor4fv(c); ``` But I would rather use something more elegant. So is there a way to access the data array in a glm::vec4 to allow access like following? ``` glColor4fv(reinterpret_cast<GLfloat*>(colors[0].data())); // .data() would hand me a pointer to the float array of the vec4 ```