Update cheatsheets

ppmforge

@@ -0,0 +1,25 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# ppmforge
+
+> Generate fractals resembling clouds, planets and starry skies.
+> More information: <https://netpbm.sourceforge.net/doc/ppmforge.html>.
+
+- Generate an image of a planet:
+
+`ppmforge > {{path/to/image.ppm}}`
+
+- Generate an image of clouds or the night sky:
+
+`ppmforge -{{night|clouds}} > {{path/to/image.ppm}}`
+
+- Use a custom mesh size and dimension for fractal generation and specify the dimensions of the output:
+
+`ppmforge -mesh {{512}} -dimension {{2.5}} -xsize {{1000}} -ysize {{1000}} > {{path/to/image.ppm}}`
+
+- Control the tilt and the angle from which the generated planet is illuminated:
+
+`ppmforge -tilt {{-15}} -hour {{12}} > {{path/to/image.ppm}}`