MeshGenerationContext

Description

Provides methods for generating a VisualElement's visual content during the generateVisualContent callback.

Visual content is generated by using the Painter2D object, or manually by allocating a mesh using the MeshGenerationContext.Allocate method and then filling the vertices and indices.

To use the painter object, access the MeshGenerationContext.painter2D property, and then use it to issue drawing commands. You can find an example in the Painter2D documentation.

If you manually provide content with MeshGenerationContext.Allocate and also provide a texture during the allocation, you can use the Vertex.uv vertex values to map it to the resulting mesh. UI Toolkit might store the texture in an internal atlas.

 class TexturedElement : VisualElement
 {
     static readonly Vertex[] k_Vertices = new Vertex[4];
     static readonly ushort[] k_Indices = { 0, 1, 2, 2, 3, 0 };

     static TexturedElement()
     {
         k_Vertices[0].tint = Color.white;
         k_Vertices[1].tint = Color.white;
         k_Vertices[2].tint = Color.white;
         k_Vertices[3].tint = Color.white;

         k_Vertices[0].uv = new Vector2(0, 0);
         k_Vertices[1].uv = new Vector2(0, 1);
         k_Vertices[2].uv = new Vector2(1, 1);
         k_Vertices[3].uv = new Vector2(1, 0);
     }

     public TexturedElement()
     {
         generateVisualContent += OnGenerateVisualContent;
         m_Texture = AssetDatabase.LoadAssetAtPath<Texture2D>("Assets/tex.png");
     }

     Texture2D m_Texture;

     void OnGenerateVisualContent(MeshGenerationContext mgc)
     {
         Rect r = contentRect;
         if (r.width < 0.01f || r.height < 0.01f)
             return; // Skip rendering when too small.

         float left = 0;
         float right = r.width;
         float top = 0;
         float bottom = r.height;

         k_Vertices[0].position = new Vector3(left, bottom, Vertex.nearZ);
         k_Vertices[1].position = new Vector3(left, top, Vertex.nearZ);
         k_Vertices[2].position = new Vector3(right, top, Vertex.nearZ);
         k_Vertices[3].position = new Vector3(right, bottom, Vertex.nearZ);

         MeshWriteData mwd = mgc.Allocate(k_Vertices.Length, k_Indices.Length, m_Texture);
         mwd.SetAllVertices(k_Vertices);
         mwd.SetAllIndices(k_Indices);
     }
 }

Properties

Public Methods