Btukfyl

I've recently been trying to learn Tikz, and I've constructed a diagram to use for my dissertation, to help show a vector being split into components that are parallel (v_b) and perpendicular (v_g) to another vector (B). A vector normal to the plane is also shown (n).

Where I am struggling is including arcs to show angles between the vectors. I want the angle from n to v_i to be labelled theta_vn, the angle between n and v_b to be labelled theta_bn and the angle between v_b and v_i to be labelled psi.

I have looked at how other people have managed this and attempted to copy, but it is throwing an error message: "Package pgf Error: No shape named origin is known." where "origin" is one of the coordinates I've specified. Any help is appreciated or just any comments on improving my code in general.

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{tikz}

usetikzlibrary{angles}

begin{document}



begin{tikzpicture}[x=0.5cm,y=0.5cm,z=0.3cm,>=stealth]

            %Defining coordinates

            coordinate (origin) at (0,0,0);

            coordinate (v_i) at (2,-14,3);

            coordinate (v_b) at (0,-4,-14);

            coordinate (normal) at (0,-10,0);



            %Drawing vectors

            draw[->,thick] (normal) -- node[left]{$vec{n}$} (origin);

            draw[->,thick] (origin) -- node[right]{$vec{v_i}$} (v_i);

            draw[->,thick] (origin) -- node[left]{$vec{v_b}$} (v_b);

            draw[->,thick] (v_b) -- node[below]{$vec{v_g}$} (v_i);



            %Drawing other lines

            draw (v_b) -- (0,1,3.5) node[above]{$vec{B}$};

            draw (normal) -- (v_i);

            draw (normal) -- (v_b);



            %Drawing angles - throwing error

            pic ["$theta_{vn}$", angle eccentricity = 1.2, angle radius = 3cm] {angle = normal -- origin -- v_i};

            pic ["$theta_{bn}$", angle eccentricity = 1.2, angle radius = 3cm] {angle = normal -- origin -- v_b};

            pic ["$psi$", angle eccentricity = 1.2, angle radius = 3cm] {angle = v_i -- origin -- v_b};

        end{tikzpicture}



end{document}

Partial answer: by removing the inter-word spacing in the angle's nodal definition and letting the tex engine know that it has to draw whatever we desire:

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{tikz}

usetikzlibrary{angles}

begin{document}

% a bit of a help from: https://tex.stackexchange.com/questions/267201/tikz-angle-between-two-vectors-and-a-projection

begin{tikzpicture}[x=0.5cm,y=0.5cm,z=0.3cm,>=stealth]

            %Defining coordinates

            coordinate (origin) at (0,0,0);

            coordinate (vi) at (2,-14,3);

            coordinate (vb) at (0,-4,-14);

            coordinate (normal) at (0,-10,0);



            %Drawing vectors

            draw[->,thick] (normal) -- node[left]{$vec{n}$} (origin);

            draw[->,thick] (origin) -- node[right]{$vec{v_i}$} (vi);

            draw[->,thick] (origin) -- node[left]{$vec{v_b}$} (vb);

            draw[->,thick] (vb) -- node[below]{$vec{v_g}$} (vi);



            %Drawing other lines

            draw (vb) -- (0,1,3.5) node[above]{$vec{B}$};

            draw (normal) -- (vi);

            draw (normal) -- (vb);



         pic [draw, angle eccentricity=1.2, angle radius = 3cm] {angle = normal--origin--vi};





         pic [draw, angle eccentricity=1.2, angle radius = 3cm] {angle = normal--origin--vb};



         pic [draw, angle eccentricity=1.2, angle radius = 3cm] {angle = vi--origin--vb};

        end{tikzpicture}



end{document}

with which you can get:

Complete answer: Now by including the additional package usepackage{quote} (I think):

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{tikz}

usetikzlibrary{angles,quotes}

begin{document}

    % a bit of help from: https://tex.stackexchange.com/questions/267201/tikz-angle-between-two-vectors-and-a-projection

    begin{tikzpicture}[x=0.5cm,y=0.5cm,z=0.3cm,>=stealth]

    %Defining coordinates

    coordinate (origin) at (0,0,0);

    coordinate (vi) at (2,-14,3);

    coordinate (vb) at (0,-4,-14);

    coordinate (normal) at (0,-10,0);



    %Drawing vectors

    draw[->,thick] (normal) -- node[left]{$vec{n}$} (origin);

    draw[->,thick] (origin) -- node[right]{$vec{v_i}$} (vi);

    draw[->,thick] (origin) -- node[left]{$vec{v_b}$} (vb);

    draw[->,thick] (vb) -- node[below]{$vec{v_g}$} (vi);



    %Drawing other lines

    draw (vb) -- (0,1,3.5) node[above]{$vec{B}$};

    draw (normal) -- (vi);

    draw (normal) -- (vb);



    pic [draw, angle eccentricity=1.2, angle radius = 3cm] {angle = normal--origin--vi};





    pic [draw, "$theta$", angle eccentricity=1.2, angle radius = 3cm] {angle = normal--origin--vb};



    pic [draw, "a", angle eccentricity=1.2, angle radius = 3cm] {angle = vi--origin--vb};

    end{tikzpicture}



end{document}

you will end up with

I took the liberty to rename your variables.