Version: 2023.2
LanguageEnglish
  • C#

MeshGenerationContext

class in UnityEngine.UIElements

/

Implemented in:UnityEngine.UIElementsModule

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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

painter2D The vector painter object used to issue drawing commands.
visualElement The element for which VisualElement.generateVisualContent was invoked.

Public Methods

AddMeshGenerationJob Instructs the renderer to wait for the completion of the provided JobHandle before beginning processing the meshes.
Allocate Allocates and draws the specified number of vertices and indices required to express geometry for drawing the content of a VisualElement.
AllocateTempMesh Allocates the specified number of vertices and indices from a temporary allocator.
DrawMesh Records a draw command with the provided triangle-list indexed mesh.
DrawText Draw a string of text.
DrawVectorImage Draws a VectorImage asset.
GetTempMeshAllocator Returns an allocator that can be used to safely allocate temporary meshes from the job system. The meshes have the same scope as those allocated by AllocateTempMesh.
InsertMeshGenerationNode Inserts a node into the rendering tree that can be populated from the job system.
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