When programming visuals, I often need to fix color values of pixels in image data where alpha is 0. Here’s a little tool called pngprep which can do some pre-processing of image data and save the result as a 32 bpp png file.
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2009-10-17
Tool: pngprep
2009-10-16
Tool update: psdslayer 1.1
A while ago I posted psdlayerstga 1.0. I have now updated it to support saving to PNG files, which is also now the default output format. The tool also got renamed to psdslayer, since I was constantly imagining, and even mistyping, the name to be “psd slayer” rather than “psd layers“. And I find it funny.
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2009-10-11
Steps and Pulses
A few years ago I read the book Texturing and Modeling: A Procedural Approach (Ebert et al.) and found some low level “step” and “pulse” primitives used for generating procedural graphics. It didn’t take a long time to notice that those are actually really useful in many other situations as well.
A generic pattern is that some value changes its value from a to b over t iterations, and you want something other to move along from c to d in the same time. Implementation is easier when the transition from a to b is just normalized to [0..1]. After that it’s really easy to map it to any range just by another multiplication (d – c) and adding an offset (c).
The “boxStep” function does the normalization part described above. However, just linear movement is actually quite boring, so the funky part here is that you can just switch “boxStep” to a “smoothStep” and there we go, movement along a smooth curve which feels better. Or you can map the boxStep result to a different function which takes in a value in the [0..1] range and outputs a value in the same range, e.g. sqrt().
2009-09-09
Tool: psdlayerstga
UPDATE: psdlayerstga has been renamed to psdslayer with addition of saving the layers as png files. Get the new tool from here.
I took DrPetter’s PSDImage code for extracting layers from PSD images, and combined it with stb_image just for saving out the layers easily as TGA files. And then I included some simple options and output of the metadata (i.e. name and position of each layer). Result is a little command-line utility, “psdlayerstga”. Use it for anything, but do so at your own risk. (The PSDImage code uses that same license, and stb_image is public domain.)
Download here, including C/C++ source and a pre-built executable for windows:
psdlayerstga.zip
Go get newer version (psdslayer) from here.
Edit: Don’t miss psdparse below (suggested by Toby), an alternative tool for the same task.