I can't get RenderCollision to work, no matter how I try. The documentation says :

RenderCollision (view_id: int, vtx_layout: VertexLayout, prg: ProgramHandle, render_state: RenderState, depth: int) -> None

Here's my (limited) understanding of what I should pass as parameters to this function :

• view_id : can be set from 0 to 255, according to the doc. In my case, it is 0
• vtx_layout : the vertex layout to store 3D lines
• ProgramHandle : the program (shader) needed to draw 3D lines
• RenderState : something I'm supposed to provide using ComputeRenderState (found it here)
• depth : something relative to the zDepth, I guess?

At this point, I feel I'm not far from using it properly, but I'm having a hard time to figure out the RenderState thing. Anyone been there before?

CodePudding user response：

RenderCollision is a debug function, so it won't "consume" any view_id. Indeed, you can pass it the view_id, it will write into the current view.

vtx_layout and prg, as you guessed it, handle the rendering of the debug lines (RenderCollision is using lines to draw the collision shapes).

It usually works this way:

Avoid clearing the view when drawing the debug info
hg.SetViewClear(view_id, hg.CF_None, 0, 1.0, 0)

Set the rect of the current view (the same as your main rendering)
hg.SetViewRect(view_id, 0, 0, screen_size_x, screen_size_y)

Set the camera transformation matrix (the same as your current camera)
hg.SetViewTransform(view_id, view_matrix, projection_matrix)

This is the one you were probably looking at: BM_Opaque will let know Harfang where you want to specifically draw within the rendering pipeline:
render_state = hg.ComputeRenderState(hg.BM_Opaque, hg.DT_Disabled, hg.FC_Disabled)

Final instruction that will draw the collision shapes:
physics.RenderCollision(view_id, vtx_line_layout, line_shader, render_state , 0)

You will find a working example here, I hope it will help: https://github.com/harfang3d/tutorials-hg2/blob/master/physics_overrides_matrix.py#L69