Manually Rendering Meshes and Models

Graphics
#1

How do you use the Mesh and Model Draw() methods? I have tried using them in a PostEffect script and attempted hooking them into some RenderTask callbacks but cannot seem it get it to work. I am attempting to draw a bunch of instances simulate to how I would do it in Unity by submitting a model and an array of Transform information.

I anticipate this might be a longer thread as I have a couple more questions regarding this but this is the first step I need to figure out.

#2

Do you want to render custom meshes into the view or implement a whole custom rendering pass?

Custom drawing pass that uses utility API to draw scene objects into a depth map:

Example how Editor’s gizmos are rendering custom meshes during editor viewport drawing callback:

#3

Currently I am just trying to Render a custom mesh with material using the RenderPipeline.
Here is a simple example of what I am trying.

public class DrawModel : PostProcessEffect
{
    
    public Model Model;

    public Material Material;

    // Just referencing Actor to use transform for debugging
    // I don't want to actualy use the Actor
    public Actor TargetTransform;
    Matrix _matrix;
    public bool Valid;

    public override bool CanRender()
    {
        Valid = (Model != null && Material != null && TargetTransform != null);
        return Valid && this.Actor.IsActiveInHierarchy;
    }

    public override void Render(GPUContext context, ref RenderContext renderContext, GPUTexture input, GPUTexture output)
    {
        _matrix = TargetTransform.Transform.GetWorld();
        Model.Draw(ref renderContext, Material, ref _matrix); // Nothing happens..
    }
}
#4

So to elaborate a little more. I’m trying to understand the graphics pipeline process.
I want to render a list of models/meshes that will render the same as Flax already does but without having to use the Renderer method that takes an actor list.

I am assuming I have to subscribe to multiple callbacks for each stage of the process (depth/gbuffer/forward) and loop through each mesh in the Model and submit a call with the material set to the specific pass.

But right now I’m just traying to get the Model.Draw() to do something lol.

#5

So far using the PostProcessScript render method will draw the objects emission when set to after deffered. I have not been able to get anything to happen using callbacks from MainRenderTask.

Since I am able to atleast get emissions to render on the PostProcessScript I am assuming I might have to bind the targets for Normal and Diffuse as they are most likely multirender targets?

#6

PostFx (as the name suggests) cannot interact with actual scene rendering that much. For this use events from Main Scene Rendering Task as follows:

public class DrawModel : Script
{
    public Model Model;
    public Material Material;
    public Actor TargetTransform;

    /// <inheritdoc />
    public override void OnEnable()
    {
        MainRenderTask.Instance.CollectDrawCalls += OnCollectDrawCalls;
    }

    /// <inheritdoc />
    public override void OnDisable()
    {
        MainRenderTask.Instance.CollectDrawCalls -= OnCollectDrawCalls;
    }

    private void OnCollectDrawCalls(ref RenderContext renderContext)
    {
        // Skip if something is missing
        if (!TargetTransform || !Model || !Material)
            return;

        // Draw model (will submit draw call)
        TargetTransform.GetLocalToWorldMatrix(out Matrix world);
        Model.Draw(ref renderContext, Material, ref world);
    }
}

But there was a bug in Flax 1.6 which was fixed in Fix double engine assembly init in Editor · FlaxEngine/FlaxEngine@03c120b · GitHub (you can use daily master build tomorrow or wait for Flax 1.7 release soon)

#7

Ahh Im glad its a bug because I was going crazy thinking I was not understanding something. Thank you for clarifying and the example