How to rotate a billboard mode Sprite3D?

poombus

I have a basic CharacterBody3D with a Sprite3D child.
The Sprite3D has billboard mode turned on so it faces the active camera.

Changing the Sprite3D's rotation doesn't do anything because it's in billboard mode (it starts rotating if I turn billboard mode off).

Is there away to allow rotation in billboard mode as if it were a Sprite2D?
If I am forced into using .look_at(), how do I fix the sprite stretching issue with the camera?

Tomcat

poombus Is there away to allow rotation in billboard mode as if it were a Sprite2D?

It's done with a simple shader. I have one, but it's for 3.x. If you wish to adapt it for 4, I can post it.

retroshark

Hey poombus! Happy to try and help here. Before I provide an answer, can you go into a bit more detail about what you are trying to achieve? You mentioned using billboard, but also not using billboard to allow for rotation. Are you hoping to have a billboard effect (facing the camera), while also allowing for rotation on another axis?

poombus

retroshark Hallo!

I tried exploring alternatives because billboard wasn't working. I'm sticking with it for now (because it's so simple), but I would like to be able to rotate the sprites.

I am hoping to have a billboard effect whilst being able to rotate the camera about the axis facing the camera. I don't think I'll need any other axis.

MagickPanda

The major function of billboards is to make the sprite/particles or whatever ALWAYS face the camera.
If I understand right, your goal is to make the smiley face quad only rotates around an arbitrary axis, rather than rotating in both x and z axes when using look_at built-in function.
For character3d node, u could just change the value of x/y/z of transform rotation variable, if u wanna rotate the model around a single axis.

poombus

MagickPanda I'm willing to go the .look_at() route as a final resort, I was just wondering if there was a more elegant solution.

poombus

Tomcat That would be helpful! I think I can port it.

Tomcat

poombus I think I can port it.

may not be exactly what you need… rotation is set in the inspector –> material –> shader param –> angle

Godot_v3.5.2

RotitionSphere.zip

shader_type spatial;

uniform sampler2D texture2D;
uniform float size = 1.;
uniform float angle = 0.;

const float PI = 3.14159265359;
 
varying vec2 tex_position;

mat2 rotate2d(float _angle){
	return mat2(vec2(cos(_angle),sin(_angle)),
				vec2(sin(_angle),-cos(_angle)));
}

void fragment () {
	tex_position = VERTEX.xy / size / 2.0 + 0.5;
	tex_position -= vec2(0.5);
	tex_position = rotate2d(angle) * tex_position; //in radians
//	tex_position = rotate2d(angle / 180.0 * PI) * tex_position; //in degrees
	tex_position += vec2(0.5);
	
	ALBEDO = texture(texture2D, tex_position).xyz;
}