Pass time to material in render script? (SOLVED)

Questions
#1

dl;dr: How do I pass constants to a material enabled in a custom render script?

Hello! I am trying to rebuild a microgame I put out in Godot with Defold, both for learning and because it’s a web game and I want to try to get that download size way down. I’m using Defold 1.9.6.

My current sticking point is shaders. Godot has a really easy way to apply a shader to an arbitrary part of the screen as opposed to an individual sprite.

I’ve used some open source code to compile Godot’s shader language into GLSL and made a fragment program out of that (with some modifications to get it working).

Then I made a new render with a material resource. That material uses the fp. It applies to the whole screen, but it looks correct.

However, I need to pass a time vec4 to the fp in order to get the effect I want. Eventually, I’ll also need to pass a vec4 to describe what part of the screen to apply the effect to, while drawing the rest of the screen normally.

So, how do I pass constants to a material being used in the render script?

Also, is this the correct approach? I had been trying to use render targets, but couldn’t get anything to work that way, and all the examples are out of date for the current version.

Thanks so much!

#2

You can use go.set() to pass values to your shader if the material has fragment/vertex constants defined. Here’s an example:

The same principle applies when you tint a sprite (tint is a constant on the sprite.material):

You can also set constants from your render script using constant buffers:

#3

Yes, the constants buffer got me there, thank you!

I had to get the constants with local constants = render.constant_buffer(), set my time constants (u_time), then add the constants to the draw_options_world local: draw_options_world.constants = constants.

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