I was wondering if there is a way to import an image sequence (something like smoke) that does not have transparency into blender and set the blending mode of that to add like in Photoshop for example. So i archive a kind of transparency in that way.
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$\begingroup$ This question is similar to: How can I remove black backgrounds from fire stock images to use in material with transparency?. Note that in the answer there it is explained why just using a greyscale value of the brightness like in the answer below is not the optimal solution for things like fire. $\endgroup$– Gordon BrinkmannCommented Jun 30 at 0:56
2 Answers
I made this quick fire simulation as an example:
To import the image sequence, the easiest way is to use the addon Import Image As Plane (enable it from the menu Edit > Preferences > Addons).
Menu File > Import > Image As Plane, select your images and set the following options:
In the shader editor, you should see your image texture node plugged into the Principled BSDF Node. Plug the texture's color output to the Principled's Alpha input. Then, add a Separate Color node and a Color Ramp node, drag them on the noodle you just created, and set the Separate to HSV and plug its Value socket. It should look as follows:
What we did here is get the "Value" data of the image sequence (the black/white), and use it as alpha. The color ramp allows you to control that alpha. Move the white stop to the left to include "more", and move the black stop to the left to include less. You can add a stop in the middle to manage the transition.
Note that what you see greatly depends on what's behind. The smoke might not be easy to see on a white background but visible on a black one:
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$\begingroup$ Which version of Blender are you using? My answer is made on v3.6.5. $\endgroup$– Lauloque ♦Commented Oct 28, 2023 at 0:10
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$\begingroup$ These setting were added back in v3.4 that was released in December 7th 2022. $\endgroup$– Lauloque ♦Commented Oct 28, 2023 at 0:17
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1$\begingroup$ Actually I think the answer I gave on my duplicate question a few months earlier works much better for fire at least... $\endgroup$ Commented Jun 30 at 1:12
Mix Node in Compositor
You could use Blender's Compositor to combine your render with your smoke card with a Mix node. The Mix node has the different blend modes you mentioned.