Forums Technical Discussion Color ramp presets - programmatically creating/adding them ?

Color ramp presets - programmatically creating/adding them ?

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nicholas_yue
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301 posts
Joined: July 2005
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Hi,

In the color ramp, there are a couple of presets e.g.
  • Black Body
  • Grayscale
  • Infra-Red
  • Two-Tone
  • White to Red

I am looking for ways to add more presets programmatically.

Attachments:
Houdini_CustomRamp.png (271.5 KB)

Nicholas Yue
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NicTanghe
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244 posts
Joined: Dec. 2016
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https://lesterbanks.com/2017/05/save-color-spline-ramps-houdini/ [lesterbanks.com]

This exists, but it's unwieldy,
If anyone knows of any other way to add presets, that would be nice.
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ajz3d
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654 posts
Joined: Aug. 2014
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My colleague wrote a tool for managing ramp presets:

https://github.com/legomir/rampage [github.com]

And if you want to programmatically create ramps, look into multiParmInstances, because that's what ramps are comprised of.

For example, the code below will generate a rainbow ramp:
# (...)
    # Note: "selection" is an array of SOPs.
    for op in selection:
        ramp = op.parm('ramp')
        if ramp is None:
            _ = "Parameter 'ramp' doesn't exist"
            hou.ui.displayMessage(_, severity=hou.severityType.Error)
            return

        # Clear the ramp
        multi = ramp.multiParmInstances()
        for _ in range(int(len(multi) / 5) -1, 0, -1):
            ramp.removeMultiParmInstance(0)

        # Create ramp points
        pos = 0
        hue = 0
        sat = 0.75
        val = 0.75
        for _ in range(0, 360):
            if not _ == 0:
                ramp.insertMultiParmInstance(_)
            # Point position
            mp_pos = '%s%dpos' % ('ramp', _ + 1)
            op.parm(mp_pos).set(pos)
            # Point color
            color = hou.Color()
            color.setHSV((hue, sat, val))
            color_pt = op.parmTuple('%s%dc' % ('ramp', _ + 1))
            color_pt.set(color.rgb())
            # Point interpolation
            op.parm('%s%dinterp' % ('ramp', _ + 1)).set(0)
            pos += 1.0 / 360
            hue += 1

        op.parm('%s%dpos' % ('ramp', len(ramp.multiParmInstances()) / 5))
Edited by ajz3d - Nov. 9, 2022 07:06:02
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