single-pass-wireframes in shader

This is an issue to track a feature I plan to add sometime soon.

The goal is to add Single-Pass Wireframe Rendering to Xenko's shaders, and use that for wireframes in the Studio, instead of 2-pass xray wireframes. Here is an example...

Why?

There are many advantages to single-pass wireframes.

• they are massively faster than 2-pass drawing of LINE primitives
• they look much nicer
• they don't have any z-fighting issues, so they can be z-clipped
• they can support advanced wireframe features, like contrast coloring, or depth-test occlusion coloring
• automatic back-face line rejection, independent of z-test

The most immediate problem this will fix is the fact that the current x-ray wireframes make placing objects very very confusing. Take a look at two screenshots..

Here is one with a character standing on a surface.

Here is one with the character "submerged" up to the waist. The x-ray wireframes make this very hard to see.

I'm guessing the current wireframes are x-ray because non-xray 2-pass wireframes have many z-fighting issues, and also it may be advantageous to see the wireframes through objects.

My plan is to add single-pass wireframes to the shader, and add some features, such as:

• allowing occluded lines to be an alternate (muted) color, or culled
• contrast-coloring lines (so on yellow objects they will appear black)

Notes:

• https://github.com/stride3d/stride/blob/master/sources/engine/Stride.Rendering/Rendering/WireframePipelineProcessor.cs
• https://github.com/stride3d/stride/blob/master/sources/engine/Stride.Graphics/RasterizerStates.cs
• https://github.com/stride3d/stride/blob/master/sources/editor/Stride.Assets.Presentation/SceneEditor/WireframeRenderFeature.cs
• https://github.com/stride3d/stride/blob/master/sources/editor/Stride.Assets.Presentation/AssetEditors/EntityHierarchyEditor/Game/EditorGameModelSelectionService.cs#L60

Start by reading WireframePipelineProcessor.cs and RasterizerStates.cs, then trace the Studio integration through WireframeRenderFeature.cs and EditorGameModelSelectionService.cs. Compare the current two-pass x-ray behavior with the linked single-pass wireframe approach. Done means Studio uses single-pass wireframes with the intended depth and occlusion behavior, including the proposed line-color or culling options.