GetUVDistributionMetric(int)

Definition

• Type: Method
• Namespace: UnityEngine
• Assembly: UnityEngine.CoreModule

public float GetUVDistributionMetric(int uvSetIndex)

Parameters

int

Returns

Remarks

Examples

using UnityEngine;public class MyMipmapClass : MonoBehaviour{    private Vector3 m_CameraPosition;    private float m_CameraEyeToScreenDistanceSquared;    private float m_MeshUVDistributionMetric;    private float m_TexelCount;    private Texture2D m_Texture;    public void SetView(Vector3 cameraPosition, float cameraHalfAngle, float screenHalfHeight, float aspectRatio)    {        m_CameraPosition = cameraPosition;        m_CameraEyeToScreenDistanceSquared = Mathf.Pow(screenHalfHeight / Mathf.Tan(cameraHalfAngle), 2.0f);        // Switch to using the horizontal dimension if larger        if (aspectRatio > 1.0f)    // Width is larger than height            m_CameraEyeToScreenDistanceSquared *= aspectRatio;    }    public void SetView(Camera camera)    {        float cameraHA = Mathf.Deg2Rad * camera.fieldOfView * 0.5f;        float screenHH = (float)camera.pixelHeight * 0.5f;        SetView(camera.transform.position, cameraHA, screenHH, camera.aspect);    }    private int CalculateMipmapLevel(Bounds bounds, float uvDistributionMetric, float texelCount)    {        // based on  http://web.cse.ohio-state.edu/~crawfis.3/cse781/Readings/MipMapLevels-Blog.html        // screenArea = worldArea * (ScreenPixels/(D*tan(FOV)))^2        // mip = 0.5 * log2 (uvArea / screenArea)        float dSq = bounds.SqrDistance(m_CameraPosition);        if (dSq < 1e-06)            return 0;        // uvDistributionMetric is the average of triangle area / uv area (a ratio from world space triangle area to normalised uv area)        // - triangle area is in world space        // - uv area is in normalised units (0->1 rather than 0->texture size)        // m_CameraEyeToScreenDistanceSquared / dSq is the ratio of screen area to world space area        float v = (texelCount * dSq) / (uvDistributionMetric * m_CameraEyeToScreenDistanceSquared);        float desiredMipLevel = 0.5f * Mathf.Log(v, 2);        return (int)desiredMipLevel;    }    // Pick the larger two scales of the 3 components and multiply together    float GetLargestAreaScale(float x, float y, float z)    {        if (x > y)        {            if (y > z)                return x * y;            else                return x * z;        }        else // x <= y        {            if (x < z)                return y * z;            else                return x * y;        }    }    public void Start()    {        Mesh mesh = GetComponent<MeshFilter>().sharedMesh;        m_MeshUVDistributionMetric = mesh.GetUVDistributionMetric(0);        // If the mesh has a transform scale or uvscale it would need to be applied here        // Transform scale:        // Use two scale values as we need an 'area' scale.        // Use the two largest component to usa a more conservative selection and pick the higher resolution mip        m_MeshUVDistributionMetric *= GetLargestAreaScale(transform.lossyScale.x, transform.lossyScale.y, transform.lossyScale.z);        // To determine uv scale for a material use Material.GetTextureScale        // If there is a uv scale to apply then divide the m_MeshUVDistributionMetric by (uvScale.x * uvScale.y)        m_TexelCount = m_Texture.width * m_Texture.height;    }    public void Update()    {        SetView(Camera.main);        m_Texture.requestedMipmapLevel = CalculateMipmapLevel(GetComponent<Renderer>().bounds, m_MeshUVDistributionMetric, m_TexelCount);    }}