Hi, I was trying to see if I could use MetaFun / MetaPost as my main tool for generating figures. I really like its close integration with ConTeXt, speed, and expressivity making it, even for a beginner like me, a pleasure to work with. One difficulty I encountered is for generating 2D functional shadings. For instance, I am not sure what is the best way to reproduce the following pgfplots picture in MetaPost: ____________________________________________________________ \usemodule[pgfplots] \pgfplotsset{width=10cm,compat=1.18} \usepgfplotslibrary{patchplots} \starttext \startTEXpage \starttikzpicture \startaxis[ hide axis=true, axis lines=none,hide axis, enlargelimits=false, scale only axis, clip bounding box=upper bound, clip=true, ] \addplot[ patch, shader=interp, mesh/color input=explicit, data cs=polar, ] coordinates { (90,4) [color=red] (210,4) [color=green] (-30,4) [color=blue] }; \stopaxis \stoptikzpicture \stopTEXpage \stoptext ____________________________________________________________ One idea is to draw a sequence of triangles, each with a linear gradient: ____________________________________________________________ \startMPpage def LinearIntTriangle(expr pa, pb, pc, cola, colb, colc, n_iter) = for i = n_iter step -1 until 1 : path p; x := i / n_iter; y := (i - 0.5) / n_iter; p := pa -- (pa + x * (pb - pa)) -- (pa + x * (pc - pa)) -- cycle; sh := define_linear_shade(pa + y * (pb - pa), pa + y * (pc - pa), (1 - y) * cola + y * colb, (1 - y) * cola + y * colc); fill p withshade sh; endfor enddef; color cola, colb, colc; cola := (0,1,0); colb := (1,0,0); colc := (0,0,1); LinearIntTriangle((0,0), (50,50*(3**0.5)), (100,0), cola, colb, colc, 30); \stopMPpage ____________________________________________________________ or to use a slight variation (decomposing the triangle in three so that the color is ‘right’) along each edge: ____________________________________________________________ \startMPpage def LinearIntTriangleB(expr pa, pb, pc, cola, colb, colc, n_iter) = color centre_color; centre_color := (cola + colb + colc) / 3; LinearIntTriangle((pa + pb + pc) / 3, pa, pb, centre_color, cola, colb, n_iter); LinearIntTriangle((pa + pb + pc) / 3, pb, pc, centre_color, colb, colc, n_iter); LinearIntTriangle((pa + pb + pc) / 3, pc, pa, centre_color, colc, cola, n_iter); enddef; color cola, colb, colc; cola := (0,1,0); colb := (1,0,0); colc := (0,0,1); LinearIntTriangleB((0,0), (50,50*(3**0.5)), (100,0), cola, colb, colc, 10); \stopMPpage ____________________________________________________________ This approach gives ‘good enough’ results for large values of n_iter. However, the size of the generated pdf is somewhat larger than the pgfplots version: for instance, the first version above generates a 5KiB pdf versus 3.8KiB for the pgfplots version, while being somewhat less accurate. Increasing n_iter to 100 gives a result which is (to my not-very-good eyes) very close to the pgfplots version but the pdf size increases to about 20KiB, and takes significantly longer to render using MuPDF. I'd be grateful if someone could point me to a better way to generate such shadings in MetaFun / MetaPost. Cheers, Florent