unity 2d 點光源/路燈/手電筒效果怎麼做？

示意圖如上。

unity 2d遊戲開發，某點光源發出的扇形光區域，夾角可調整，角平分線斜率可調整。shader小白，應該怎麼實現上述效果呢？

---

2d的話直接畫三角扇就可以，邊緣alpha衰減，再加個雜訊圖模擬浮沉感覺。

3d的話我這倒是有個函數，模擬聚光燈的。

private Mesh CreateSpotLightMesh()

{

// copy pasted from other project, the geometry is too complex, should be simplified

Mesh mesh = new Mesh();

const int segmentCount = 16;

Vector3[] vertices = new Vector3[2 + segmentCount * 3];

Color32[] colors = new Color32[2 + segmentCount * 3];

vertices[0] = new Vector3(0, 0, 0);

vertices[1] = new Vector3(0, 0, 1);

float angle = 0;

float step = Mathf.PI * 2.0f / segmentCount;

float ratio = 0.9f;

for (int i = 0; i &< segmentCount; ++i)

{

vertices[i + 2] = new Vector3(-Mathf.Cos(angle) * ratio, Mathf.Sin(angle) * ratio, ratio);

colors[i + 2] = new Color32(255, 255, 255, 255);

vertices[i + 2 + segmentCount] = new Vector3(-Mathf.Cos(angle), Mathf.Sin(angle), 1);

colors[i + 2 + segmentCount] = new Color32(255, 255, 255, 0);

vertices[i + 2 + segmentCount * 2] = new Vector3(-Mathf.Cos(angle) * ratio, Mathf.Sin(angle) * ratio, 1);

colors[i + 2 + segmentCount * 2] = new Color32(255, 255, 255, 255);

angle += step;

}

mesh.vertices = vertices;

mesh.colors32 = colors;

int[] indices = new int[segmentCount * 3 * 2 + segmentCount * 6 * 2];

int index = 0;

for (int i = 2; i &< segmentCount + 1; ++i)

{

indices[index++] = 0;

indices[index++] = i;

indices[index++] = i + 1;

}

indices[index++] = 0;

indices[index++] = segmentCount + 1;

indices[index++] = 2;

for (int i = 2; i &< segmentCount + 1; ++i)

{

indices[index++] = i;

indices[index++] = i + segmentCount;

indices[index++] = i + 1;

indices[index++] = i + 1;

indices[index++] = i + segmentCount;

indices[index++] = i + segmentCount + 1;

}

indices[index++] = 2;

indices[index++] = 1 + segmentCount;

indices[index++] = 2 + segmentCount;

indices[index++] = 2 + segmentCount;

indices[index++] = 1 + segmentCount;

indices[index++] = 1 + segmentCount + segmentCount;

//------------

for (int i = 2 + segmentCount; i &< segmentCount + 1 + segmentCount; ++i)

{

indices[index++] = i;

indices[index++] = i + segmentCount;

indices[index++] = i + 1;

indices[index++] = i + 1;

indices[index++] = i + segmentCount;

indices[index++] = i + segmentCount + 1;

}

indices[index++] = 2 + segmentCount;

indices[index++] = 1 + segmentCount * 2;

indices[index++] = 2 + segmentCount * 2;

indices[index++] = 2 + segmentCount * 2;

indices[index++] = 1 + segmentCount * 2;

indices[index++] = 1 + segmentCount * 3;

////-------------------------------------

for (int i = 2 + segmentCount * 2; i &< segmentCount * 3 + 1; ++i)

{

indices[index++] = 1;

indices[index++] = i + 1;

indices[index++] = i;

}

indices[index++] = 1;

indices[index++] = 2 + segmentCount * 2;

indices[index++] = segmentCount * 3 + 1;

mesh.triangles = indices;

mesh.RecalculateBounds();

return mesh;

}

---

直接做一個三角形的面片，然後在上面放一個邊緣發光中間略微透明的貼圖，用particles/additive這個shader可以模擬一個這樣的效果。

---

最後還是去asset store里找到了一個插件，小貴但基本能滿足問題需求。

2D Dynamic Lights and Shadows - 2DDL PRO

這裡面有很多2d光照的案例，手電筒、蠟燭、雷達什麼的都有，代碼略複雜，看得懂的話可以參考。

---

濾鏡SHADER實現

---

推薦閱讀：