[4.0 beta11] GeometryInstance3D transparency parameter hide mesh with value over 0.0

[jmb462]

Godot version

4.0 beta 11

System information

Windows10

Issue description

When setting GeometryInstance3D transparency parameter to a value higher than zero, mesh do not appear anymore if material transparency is not enabled.

Worked fine in beta10 even if material was not set to transparent.

Not sure if it's a regression or a bug fix...

Steps to reproduce

1. Add a MeshInstance3D with a Box shape
2. Change the transparency setting in GeometryInstance3D

Mesh disappears.

Beta 11 :

Beta 10 :

Minimal reproduction project

transparency_bug.zip

[clayjohn]

I noticed this as well. There is already a PR fixing it that just needs to be merged #71124

[fracteed]

@clayjohn I am not sure if this feature is intended to work on the mobile and opengl renderers or not? Can be hard to find this sort of info, and I didn't want to open up a new issue if it is a known limitation.

[clayjohn]

@fracteed it should work on all rendering backends

[fracteed]

@clayjohn I have tried it on a few pc's and it only works in 4.0.2 on the forward+ renderer. Do you want me to open up another issue?

[clayjohn]

@clayjohn I have tried it on a few pc's and it only works in 4.0.2 on the forward+ renderer. Do you want me to open up another issue?

Yes please. I took a quick look and it looks like it just hasn't been implemented. It would be nice to have an issue to track it. It should not be a lot of work to implement as the implementation can be copied directly from the clustered renderer.

Code for reference

godot/servers/rendering/renderer_rd/forward_clustered/render_forward_clustered.cpp

Lines 845 to 860 in 8c729f0

	float fade_alpha = 1.0;
	if (inst->fade_near || inst->fade_far) {
	float fade_dist = inst->transform.origin.distance_to(p_render_data->scene_data->cam_transform.origin);
	// Use `smoothstep()` to make opacity changes more gradual and less noticeable to the player.
	if (inst->fade_far && fade_dist > inst->fade_far_begin) {
	fade_alpha = Math::smoothstep(0.0f, 1.0f, 1.0f - (fade_dist - inst->fade_far_begin) / (inst->fade_far_end - inst->fade_far_begin));
	} else if (inst->fade_near && fade_dist < inst->fade_near_end) {
	fade_alpha = Math::smoothstep(0.0f, 1.0f, (fade_dist - inst->fade_near_begin) / (inst->fade_near_end - inst->fade_near_begin));
	}
	}
	fade_alpha *= inst->force_alpha * inst->parent_fade_alpha;
	flags = (flags & ~INSTANCE_DATA_FLAGS_FADE_MASK) | (uint32_t(fade_alpha * 255.0) << INSTANCE_DATA_FLAGS_FADE_SHIFT);