glm.project(obj, model, proj, viewport) suspicious code

[Philip-Trettner]

Hi, I stumbled upon a strange line of code in public static vec3 project(vec3 obj, mat4 model, mat4 proj, vec4 viewport) the line in question is: tmp = tmp*((0.5f) + (0.5f)); ( https://github.com/dwmkerr/glmnet/blob/master/source/GlmNet/GlmNet/matrix_transform.cs#L223 )

This is either a bug or could be simplified.

[dwmkerr]

That indeed looks very suspicious, let me check against the C++ version.

[dwmkerr]

Good eyes @Philip-Trettner, the original is:

template <typename T, typename U, precision P>
    GLM_FUNC_QUALIFIER detail::tvec3<T, P> project
    (
        detail::tvec3<T, P> const & obj,
        detail::tmat4x4<T, P> const & model,
        detail::tmat4x4<T, P> const & proj,
        detail::tvec4<U, P> const & viewport
    )
    {
        detail::tvec4<T, P> tmp = detail::tvec4<T, P>(obj, T(1));
        tmp = model * tmp;
        tmp = proj * tmp;

        tmp /= tmp.w;
        tmp = tmp * T(0.5) + T(0.5);
        tmp[0] = tmp[0] * T(viewport[2]) + T(viewport[0]);
        tmp[1] = tmp[1] * T(viewport[3]) + T(viewport[1]);

        return detail::tvec3<T, P>(tmp);
    }

so indeed it is a bug. This function should be covered by a test ideally. I'm making the fix now.

[dwmkerr]

Fixed in 0.5.1, cheers @Philip-Trettner!