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using UnityEngine;
using UnityEngine.UI;
// For a discussion of the code, see: https://www.hallgrimgames.com/blog/2018/11/25/custom-unity-ui-meshes
public class MyUiElement : MaskableGraphic
{
public float GridCellSize = 40f;
[SerializeField]
Texture m_Texture;
// make it such that unity will trigger our ui element to redraw whenever we change the texture in the inspector
public Texture texture
{
get
{
return m_Texture;
}
set
{
if (m_Texture == value)
return;
m_Texture = value;
SetVerticesDirty();
SetMaterialDirty();
}
}
protected override void OnRectTransformDimensionsChange()
{
base.OnRectTransformDimensionsChange();
SetVerticesDirty();
SetMaterialDirty();
}
// if no texture is configured, use the default white texture as mainTexture
public override Texture mainTexture
{
get
{
return m_Texture == null ? s_WhiteTexture : m_Texture;
}
}
// helper to easily create quads for our ui mesh. You could make any triangle-based geometry other than quads, too!
void AddQuad(VertexHelper vh, Vector2 corner1, Vector2 corner2, Vector2 uvCorner1, Vector2 uvCorner2)
{
var i = vh.currentVertCount;
UIVertex vert = new UIVertex();
vert.color = this.color; // Do not forget to set this, otherwise
vert.position = corner1;
vert.uv0 = uvCorner1;
vh.AddVert(vert);
vert.position = new Vector2(corner2.x, corner1.y);
vert.uv0 = new Vector2(uvCorner2.x, uvCorner1.y);
vh.AddVert(vert);
vert.position = corner2;
vert.uv0 = uvCorner2;
vh.AddVert(vert);
vert.position = new Vector2(corner1.x, corner2.y);
vert.uv0 = new Vector2(uvCorner1.x, uvCorner2.y);
vh.AddVert(vert);
vh.AddTriangle(i+0,i+2,i+1);
vh.AddTriangle(i+3,i+2,i+0);
}
// actually update our mesh
protected override void OnPopulateMesh(VertexHelper vh)
{
// Let's make sure we don't enter infinite loops
if (GridCellSize <= 0)
{
GridCellSize = 1f;
Debug.LogWarning("GridCellSize must be positive number. Setting to 1 to avoid problems.");
}
// Clear vertex helper to reset vertices, indices etc.
vh.Clear();
// Bottom left corner of the full RectTransform of our UI element
var bottomLeftCorner = new Vector2(0,0) - rectTransform.pivot;
bottomLeftCorner.x *= rectTransform.rect.width;
bottomLeftCorner.y *= rectTransform.rect.height;
// Place as many square grid tiles as fit inside our UI RectTransform, at any given GridCellSize
for (float x = 0; x < rectTransform.rect.width-GridCellSize; x += GridCellSize)
{
for (float y = 0; y < rectTransform.rect.height-GridCellSize; y += GridCellSize)
{
AddQuad(vh,
bottomLeftCorner + x*Vector2.right + y*Vector2.up,
bottomLeftCorner + (x+GridCellSize)*Vector2.right + (y+GridCellSize)*Vector2.up,
Vector2.zero, Vector2.one); // UVs
}
}
Debug.Log("Mesh was redrawn!");
}
}
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