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我正在尝试统一渲染许多（1M）个立方体，它们都具有不同的旋转、位置和颜色。位置和颜色工作正常，但旋转计算错误。当我将它们围绕 x 或 z 轴旋转 180 度以上时，它主要表现出来。这是我的代码：

Shader "Instanced/InstancedSurfaceShader" {
Properties {
    _MainTex ("Albedo (RGB)", 2D) = "white" {}
    _Glossiness ("Smoothness", Range(0,1)) = 0.5
    _Metallic ("Metallic", Range(0,1)) = 0.0
}
SubShader {
    Tags { "RenderType"="Opaque" }
    LOD 200

    CGPROGRAM
    // Physically based Standard lighting model
    #pragma surface surf Standard addshadow fullforwardshadows
    #pragma multi_compile_instancing
    #pragma instancing_options procedural:setup

    sampler2D _MainTex;

    struct Input {
        float2 uv_MainTex;
    };

#ifdef UNITY_PROCEDURAL_INSTANCING_ENABLED
    StructuredBuffer<float4> positionBuffer;
    StructuredBuffer<float4> colorBuffer;
    StructuredBuffer<float4> rotationBuffer;
#endif
    void setup()
    {

#ifdef UNITY_PROCEDURAL_INSTANCING_ENABLED
    float4 position     = positionBuffer[unity_InstanceID];
    float4 q             = rotationBuffer[unity_InstanceID];
    float qr            = q[0];
    float qi            = q[1];
    float qj            = q[2];
    float qk            = q[3];

    float4x4 rotation;
    float4x4 translation = {
        1,0,0,position.x,
        0,1,0,position.y,
        0,0,1,position.z,
        0,0,0,1
    };

    // quaternion to matrix
    // http://www.euclideanspace.com/maths/geometry/rotations/conversions/quaternionToMatrix/
    // https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#Quaternion-derived_rotation_matrix

    rotation[0][0]            = 1.0f - 2.0f*qj*qj - 2.0f*qk*qk;
    rotation[0][1]            = 2.0f*(qi*qj - qk*qr);
    rotation[0][2]            = 2.0f*(qi*qk + qj*qr);
    rotation[0][3]            = 0.0f;

    rotation[1][0]            = 2.0f*(qi*qj+qk*qr);
    rotation[1][1]            = 1.0f - 2.0f*qi*qi - 2.0f*qk*qk;
    rotation[1][2]            = 2.0f*(qj*qk - qi*qr);
    rotation[1][3]            = 0.0f;

    rotation[2][0]            = 2.0f*(qi*qk - qj*qr);
    rotation[2][1]            = 2.0f*(qj*qk + qi*qr);
    rotation[2][2]            = 1.0f - 2.0f*qi*qi - 2.0f*qj*qj;
    rotation[2][3]            = 0.0f;

    rotation[3][0]            = 0.0f;
    rotation[3][1]            = 0.0f;
    rotation[3][2]            = 0.0f;
    rotation[3][3]            = 1.0f;

    unity_ObjectToWorld = mul(translation, rotation);
    //unity_WorldToObject = inverse(unity_ObjectToWorld);
     
    // inverse transform matrix
    // taken from richardkettlewell's post on
    // https://forum.unity3d.com/threads/drawmeshinstancedindirect-example-comments-and-questions.446080/

    float3x3 w2oRotation;
    w2oRotation[0] = unity_ObjectToWorld[1].yzx * unity_ObjectToWorld[2].zxy - unity_ObjectToWorld[1].zxy * unity_ObjectToWorld[2].yzx;
    w2oRotation[1] = unity_ObjectToWorld[0].zxy * unity_ObjectToWorld[2].yzx - unity_ObjectToWorld[0].yzx * unity_ObjectToWorld[2].zxy;
    w2oRotation[2] = unity_ObjectToWorld[0].yzx * unity_ObjectToWorld[1].zxy - unity_ObjectToWorld[0].zxy * unity_ObjectToWorld[1].yzx;

    float det = dot(unity_ObjectToWorld[0], w2oRotation[0]);

    w2oRotation = transpose(w2oRotation);

    w2oRotation *= rcp(det);

    float3 w2oPosition = mul(w2oRotation, -unity_ObjectToWorld._14_24_34);

    unity_WorldToObject._11_21_31_41 = float4(w2oRotation._11_21_31, 0.0f);
    unity_WorldToObject._12_22_32_42 = float4(w2oRotation._12_22_32, 0.0f);
    unity_WorldToObject._13_23_33_43 = float4(w2oRotation._13_23_33, 0.0f);
    unity_WorldToObject._14_24_34_44 = float4(w2oPosition, 1.0f);

#endif


    }

    half _Glossiness;
    half _Metallic;
    UNITY_INSTANCING_BUFFER_START(Props)
       UNITY_DEFINE_INSTANCED_PROP(fixed4, _Color)
    UNITY_INSTANCING_BUFFER_END(Props)
    void surf (Input IN, inout SurfaceOutputStandard o) {
        fixed4 c = {0,0,255,0};//tex2D (_MainTex, IN.uv_MainTex);
        #ifdef UNITY_PROCEDURAL_INSTANCING_ENABLED
            c=colorBuffer[unity_InstanceID];
        #endif
        o.Albedo = c.rgb;
        o.Metallic = _Metallic;
        o.Smoothness = _Glossiness;
        o.Alpha = c.a;
    }
    ENDCG
}
FallBack "Diffuse"

}

也许矩阵计算有问题？

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1 回答 1

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WebGL 使用右手规则方向，您可能正在从左手规则系统（如 Unity3D）移植代码。您可以通过调整设置翻译的行来交换它 - 交换 X 和 Z 的分配，看看其余的是否符合要求。

于 2021-12-30T16:10:25.467 回答