[游戏开发]Unity3d打孔

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1.必须使用专用的着色器shader

2.使用时根据实限情况动态修改着色器shader的参数，MultipleTubesExample.cs必须挂载在要打孔的最上层节点上。

Shader "CrossSection/Unlit/Texture" {
Properties {
	_MainTex ("Base (RGB)", 2D) = "white" {}
	_SectionColor ("Section Color", Color) = (1,0,0,1)
}

SubShader {
	Tags { "RenderType"="Opaque" }
	LOD 100
	Cull off
	Pass {  
		CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma target 2.0
			#pragma multi_compile_fog

			#pragma multi_compile __ CLIP_PLANE CLIP_TWO_PLANES CLIP_SPHERE CLIP_CUBE CLIP_TUBES CLIP_BOX
		 
			#include "CGIncludes/section_clipping_CS.cginc"

			fixed4 _SectionColor;
			
			#include "UnityCG.cginc"

			struct appdata_t {
				float4 vertex : POSITION;
				float2 texcoord : TEXCOORD0;
				float3 normal    : NORMAL;
				UNITY_VERTEX_INPUT_INSTANCE_ID
			};

			struct v2f {
				float4 vertex : SV_POSITION;
				float2 texcoord : TEXCOORD0;
				float4 wpos : TEXCOORD2;
				UNITY_FOG_COORDS(1)
				UNITY_VERTEX_OUTPUT_STEREO
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			
			v2f vert (appdata_t v)
			{
				v2f o;
				UNITY_SETUP_INSTANCE_ID(v);
				UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
				float3 worldPos = mul (unity_ObjectToWorld, v.vertex).xyz;

				float3 viewDir = normalize(ObjSpaceViewDir(v.vertex));
				float dotProduct = dot(v.normal, viewDir);
				//if(dotProduct<0) v.vertex.xyz -= v.normal * _BackfaceExtrusion;

				o.wpos.w = dotProduct;
				o.wpos.xyz = worldPos;
				UNITY_TRANSFER_FOG(o,o.vertex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				//PLANE_CLIP(i.wpos.xyz);
				#if CLIP_BOX
				PLANE_CLIPWITHCAPS(i.wpos.xyz);
				#else
				PLANE_CLIP(i.wpos.xyz);
				#endif
				//fixed4 col = (i.wpos.w>0)? tex2D(_MainTex, i.texcoord): _SectionColor;
				//UNITY_APPLY_FOG(i.fogCoord, col);
				//UNITY_OPAQUE_ALPHA(col.a);
				return tex2D(_MainTex, i.texcoord);
			}
		ENDCG
	}
}

}

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.EventSystems;

public class MultipleTubesExample : MonoBehaviour {

    private Vector4[] centerPoints;
    private Vector4[] AxisDirs;
    private float[] radiuses;
    //最多64个
    [Range(0, 64)]
    //当前数量限制
    public int n = 5;
    private int i = 0;

	void Start () {
        centerPoints = new Vector4[64];
        AxisDirs = new Vector4[64];
        radiuses = new float[64];
        Shader.SetGlobalInt("_centerCount", 0);
        Renderer[] allrenderers = gameObject.GetComponentsInChildren<Renderer>();
        foreach (Renderer r in allrenderers)
        {
            Material[] mats = r.sharedMaterials;
            foreach (Material m in mats) if (m.shader.name.Substring(0, 13) == "CrossSection/") m.DisableKeyword("CLIP_PLANE");
        }
    }
	
	void Update () {
        
        if (Input.GetMouseButtonDown(0))
        {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit;
            if (Physics.Raycast(ray, out hit))
            {
                if (hit.transform.IsChildOf(transform))
                {
                    Shader.EnableKeyword("CLIP_TUBES");

                    int k = i % n;
                    Debug.Log(k);

                    //圆柱中心点
                    centerPoints[k] = hit.point;

                    //圆柱方向
                    AxisDirs[k] = (hit.point - Camera.main.transform.position).normalized;

                    //半径
                    radiuses[k] = 50.0f;

                    Shader.SetGlobalVectorArray("_centerPoints", centerPoints);
                    Shader.SetGlobalVectorArray("_AxisDirs", AxisDirs);
                    Shader.SetGlobalFloatArray("_Radiuses", radiuses);

                    i++;
                    Shader.SetGlobalInt("_centerCount", (int)Mathf.Min(i, n));
                    Shader.SetGlobalInt("_tubeCount", (int)Mathf.Min(i, n));
                }
            }
        }
	}

    void OnEnable()
    {
        Shader.EnableKeyword("CLIP_TUBES");
    }

    void OnDisable()
    {
        Shader.DisableKeyword("CLIP_TUBES");
        Shader.SetGlobalInt("_hitCount", 0);
    }

    void OnApplicationQuit()
    {
        //disable clipping so we could see the materials and objects in editor properly
        Shader.DisableKeyword("CLIP_TUBES");
    }
}