Draw a semisphere on larger circle of this Frustum of a cone - TeX

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user 3.14159

The upper circle can be drawn with the `circle on sphere` pic. We can add the frustum, but need to make sure that the upper circle does not get overwritten. This can be accomplished with a clip.
```
\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{calc,decorations.pathreplacing,3dtools}%https://github.com/marmotghost/tikz-3dtools
\begin{document}

\begin{tikzpicture}[3d/install view=%
	{phi=110,psi=180,theta=60},
	declare function={R=5;r=3;h=3;}]
	\path[3d/visible/.append style={postaction={store path=fc}}] 
		pic{3d/circle on sphere={R=R,P={(0,0,0)},n={(0,0,1)}}};
	\path [stored path/first coordinate of=fc] coordinate (fc1)
	 [stored path/last coordinate of=fc] coordinate (fc2);
	\begin{scope}	
	 \path[opacity=0] pic{3d/frustum={R=R,r=r,h=h}};
	 \clip (fc1) -- (fc2) -- (fc2-|current bounding box.east) 
	  -- (current bounding box.south east)
	  -- (current bounding box.south west)
	  -- (fc1-|current bounding box.west) -- cycle;
     \path pic{3d/frustum={R=R,r=r,h=h}}; 
	\end{scope}
	\draw[3d/screen coords] (fc1) arc[start angle=180,end angle=0,radius=R];
\end{tikzpicture}
\end{document}
```
![Screen Shot 2021-03-05 at 11.27.09 PM.png](/image?hash=2ff7d3a1ad01049931c80aef6b50ddc9d649d1e29e31fdec268c8194b1197cc1)

``` \documentclass[tikz,border=3mm]{standalone} \usetikzlibrary{calc,3dtools}% https://github.com/marmotghost/tikz-3dtools \begin{document} \begin{tikzpicture}[3d/install view={phi=70,theta=70},scale=1,line cap=butt,line join=round,c/.style={circle,fill,inner sep=1pt}, declare function={r=3;h=3;}] \path (0,0,0) coordinate (C); \path pic[xslant=0.2](Cone){3d/cone={r=r,h=h}}; \draw[3d/hidden] (Cone-tip) -- (C-|Cone-tip); \end{tikzpicture} \end{document} ```

I use `\pic[xslant=0.2]{3d/cone={r=r,h=h}};` to draw an oblique cone. ``` \documentclass[tikz,border=3mm]{standalone} \usetikzlibrary{calc,3dtools}% https://github.com/marmotghost/tikz-3dtools \begin{document} \begin{tikzpicture}[3d/install view={phi=70,theta=70},scale=1,line cap=butt,line join=round,c/.style={circle,fill,inner sep=1pt}, declare function={r=3;h=3;}] \path (0,0,0) coordinate (C) (0,0,h) coordinate (T); \pic[xslant=0.2]{3d/cone={r=r,h=h}}; \path foreach \p/\g in {C/-90,T/90} {(\p)node[c]{}+(\g:2.5mm) node{$\p$}}; \draw[3d/hidden] (T) -- (C); \end{tikzpicture} \end{document} ``` ![ScreenHunter 234.png](/image?hash=adb7b97e7858166002bdb9ec76a819160df6902d87a4643a653a4dbb0afecd22) How to get a oblique like this? ![ScreenHunter 235.png](/image?hash=bd8ed8c161e12f79f67d7b40ff9328bfe4b71beede75bbd8876f7d486de84562)

Yes. ``` \documentclass[tikz,border=3mm]{standalone} \usetikzlibrary{calc,3dtools}%https://github.com/marmotghost/tikz-3dtools \begin{document} \begin{tikzpicture}[3d/install view=% {phi=110,psi=180,theta=60}, declare function={R=5;r=3;h=3;}] \draw (0,0,-4) coordinate(T) circle[radius=R]; \path (0,0,0) coordinate (O); \draw[3d/screen coords] (O-|-R,0) -- (T-|-R,0) (O-|R,0) -- (T-|R,0); \begin{scope} \path[opacity=0] (0,0,0) pic{3d/frustum={R=R,r=r,h=h}}; \clip[3d/screen coords] (-R,0) -- (R,0) -- (0,0-|current bounding box.east) -- (current bounding box.south east) -- (current bounding box.south west) -- (0,0-|current bounding box.west) -- cycle; \path (0,0,0) pic{3d/frustum={R=R,r=r,h=h}}; \end{scope} \end{tikzpicture} % \begin{tikzpicture}[3d/install view=% {phi=110,psi=180,theta=60}, declare function={R=5;r=3;h=3;}] \path[3d/install view={phi=110,psi=0,theta=60}] pic{3d/cone={r=R,h=5}}; \begin{scope} \path[opacity=0] (0,0,0) pic{3d/frustum={R=R,r=r,h=h}}; \clip[3d/screen coords] (-R,0) -- (R,0) -- (0,0-|current bounding box.east) -- (current bounding box.south east) -- (current bounding box.south west) -- (0,0-|current bounding box.west) -- cycle; \path (0,0,0) pic{3d/frustum={R=R,r=r,h=h}}; \end{scope} \end{tikzpicture} \end{document} ```

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