HelloTriangle.cs

using System;
using AtomicEngine;

//################ Render.xml
//<renderpath>
//    <command type="sendevent"/>
//</renderpath>

public class Program
{
    public static void Main(string[] args)
    {
        Application.Run<Game>(args);
    }
}

public class Game : AppDelegate
{
    public override void Start()
    {
        var graphics = AtomicNET.GetSubsystem<Graphics>();

        pixelShader = graphics.GetShader(ShaderType.PS, "Atomic2D");
        vertexShader = graphics.GetShader(ShaderType.VS, "Atomic2D");
        vertexBuffer = new VertexBuffer();
        vertexBuffer.SetSize(12, Constants.MASK_POSITION | Constants.MASK_COLOR, true);

        var renderer = AtomicNET.GetSubsystem<Renderer>();
        var viewport = renderer.GetViewport(0);
            
        var cache = GetSubsystem<ResourceCache>();

        var renderpath = viewport.GetRenderPath().Clone();
        renderpath.Append(cache.GetResource<XMLFile>("Render.xml"));
        viewport.SetRenderPath(renderpath);

        graphics.SetShaders(vertexShader, pixelShader);
        graphics.SetShaderParameter(ShaderParams.VSP_MODEL, Matrix3x4.IDENTITY);
        graphics.SetShaderParameter(ShaderParams.PSP_MATDIFFCOLOR, Color.White);
        graphics.SetCullMode(CullMode.CULL_NONE);

        var scene = new Scene();
        scene.CreateComponent<Octree>();

        camera = scene.CreateChild("Camera").CreateComponent<Camera>();
        camera.Node.Position = new Vector3(0.5f, 0.5f, 0.0f);
        camera.Orthographic = true;
        camera.OrthoSize = 1.5f;

        viewport.Scene = scene;
        viewport.Camera = camera;

        SubscribeToEvent("RenderPathEvent", (u, e) => { Render(); });
    }

    VertexBuffer vertexBuffer;
    ShaderVariation pixelShader;
    ShaderVariation vertexShader;

    private Camera camera;

    unsafe void Render()
    {
        IntPtr vertexData = vertexBuffer.Lock(0, 12, true); {
            float* vout = (float*) vertexData;

            vout[0] = 0;
            vout[1] = 0;
            vout[2] = 0;
            vout[3] = 0xFFFF0000;

            vout[4] = 1;
            vout[5] = 0;
            vout[6] = 0;
            vout[7] = 0xFF00FF00;

            vout[8] = 0.5f;
            vout[9] = 1;
            vout[10] = 0;
            vout[11] = 0xFF0000FF;

        } vertexBuffer.Unlock();

        AtomicNET.GetSubsystem<Renderer>().GetViewport(0).View.SetCameraShaderParameters(camera);

        var graphics = AtomicNET.GetSubsystem<Graphics>();
        graphics.SetDefaultTextureFilterMode(TextureFilterMode.FILTER_NEAREST);
        graphics.SetBlendMode(BlendMode.BLEND_ALPHA);
            
        graphics.Clear(0x1, Color.White);
            
        graphics.SetVertexBuffer(vertexBuffer);
        graphics.Draw(PrimitiveType.TRIANGLE_LIST, 0, 12);
    }
}