Shaded wireframes.

[fire]

Fixes godotengine/godot-proposals#1000

• Make a view menu option.
• Fix rendering flickering problem
• Grow the wireframe

This renders twice.

HELP! Need to understand why it's flickering.

Alternative implementation is using geometry? compute? shaders and https://github.com/XRTK/XRTK-Core/blob/8bd7559136374f6d6ae804d9e311a4d60ae0ae6c/XRTK-Core/Packages/com.xrtk.core/Runtime/StandardAssets/Shaders/XRTK_Wireframe.shader

[Calinou]

HELP! Need to understand why it's flickering.

Maybe it's Z-fighting with the geometry behind the wireframe? I'm not sure how other rendering engines handle this.

Looking at how Red Eclipse renders outlines, it seems to be using parts of OpenGL dedicated to polygon offset.

Polygon offset enabled (default)

Polygon offset disabled

[Zireael07]

Maybe make the wireframe be a second pass that uses a small grow effect (grow as in what the SpatialMaterial does, not too sure of the shader equivalent)?

Most likely it's Z-fighting indeed.

[fire]

[fire]

Grow looks like:

		wireframe_material_shader = storage->shader_create();
		storage->shader_set_code(wireframe_material_shader, "shader_type spatial;\nrender_mode wireframe,unshaded;\n void fragment() { VERTEX+=NORMAL*Vector3(0.01,0.01,0.01);ALBEDO=vec3(0.0,0.0,0.0); }");
		wireframe_material = storage->material_create();
		storage->material_set_shader(wireframe_material, wireframe_material_shader);

[fire]

The flickering is very weird. It seems to be toggling modes when close to the mesh.

[fire]

This pr is salvagable. However, I am not working on it.