unity实现贴图矩阵运算（旋转平移缩放）

我们在shader中对贴图处理时，有时候会有一些比较复杂的运算，比方说三角函数，开方等，一般情况下，如果可以在越上层做运算，性能会越高。C# > Vertex > fragment

因此，考虑到贴图的旋转用到的三角函数，可以使用在C#中传入旋转矩阵得到，然后使用uv直接乘以矩阵就可以了。

封装了vmatrix4x4，分享一下：

using UnityEngine;

namespace D11.Skin
{
 public class VMatrix
 {
  public float[,] m;

  public VMatrix()
  {
   m = new float[4, 4];
   m[0, 0] = 0.0f; m[0, 1] = 0.0f; m[0, 2] = 0.0f; m[0, 3] = 0.0f;
   m[1, 0] = 0.0f; m[1, 1] = 0.0f; m[1, 2] = 0.0f; m[1, 3] = 0.0f;
   m[2, 0] = 0.0f; m[2, 1] = 0.0f; m[2, 2] = 0.0f; m[2, 3] = 0.0f;
   m[3, 0] = 0.0f; m[3, 1] = 0.0f; m[3, 2] = 0.0f; m[3, 3] = 0.0f;
  }

  public static void MatrixSetIdentity(VMatrix matrix)
  {
   matrix.m[0,0] = 1.0f; matrix.m[0,1] = 0.0f; matrix.m[0,2] = 0.0f; matrix.m[0,3] = 0.0f;
   matrix.m[1,0] = 0.0f; matrix.m[1,1] = 1.0f; matrix.m[1,2] = 0.0f; matrix.m[1,3] = 0.0f;
   matrix.m[2,0] = 0.0f; matrix.m[2,1] = 0.0f; matrix.m[2,2] = 1.0f; matrix.m[2,3] = 0.0f;
   matrix.m[3,0] = 0.0f; matrix.m[3,1] = 0.0f; matrix.m[3,2] = 0.0f; matrix.m[3,3] = 1.0f;
  }

  public static void MatrixBuildTranslation(VMatrix matrix, float x, float y, float z)
  {
   MatrixSetIdentity(matrix);
   matrix.m[0,3] = x;
   matrix.m[1,3] = y;
   matrix.m[2,3] = z;
  }

  public static void MatrixBuildTranslation(VMatrix matrix, Vector3 vec)
  {
   MatrixSetIdentity(matrix);
   matrix.m[0, 3] = vec.x;
   matrix.m[1, 3] = vec.y;
   matrix.m[2, 3] = vec.z;
  }

  public static void MatrixBuildScale(VMatrix matrix, float x, float y, float z)
  {
   matrix.m[0, 0] = x; matrix.m[0, 1] = 0.0f; matrix.m[0, 2] = 0.0f; matrix.m[0, 3] = 0.0f;
   matrix.m[1, 0] = 0.0f; matrix.m[1, 1] = y; matrix.m[1, 2] = 0.0f; matrix.m[1, 3] = 0.0f;
   matrix.m[2, 0] = 0.0f; matrix.m[2, 1] = 0.0f; matrix.m[2, 2] = z; matrix.m[2, 3] = 0.0f;
   matrix.m[3, 0] = 0.0f; matrix.m[3, 1] = 0.0f; matrix.m[3, 2] = 0.0f; matrix.m[3, 3] = 1.0f;
  }

  public static void MatrixBuildScale(VMatrix matrix, Vector3 scale)
  {
   MatrixBuildScale(matrix, scale.x, scale.y, scale.z);
  }

  public static void MatrixBuildRotate(VMatrix matrix, float angleDegrees)
  {
   float radians = angleDegrees * (Mathf.PI / 180.0f);

   float fSin = Mathf.Sin(radians);
   float fCos = Mathf.Cos(radians);
   matrix.m[0, 0] = fCos; matrix.m[0, 1] = -fSin; matrix.m[0, 2] = 0.0f; matrix.m[0, 3] = 0.0f;
   matrix.m[1, 0] = fSin; matrix.m[1, 1] = fCos; matrix.m[1, 2] = 0.0f; matrix.m[1, 3] = 0.0f;
   matrix.m[2, 0] = 0.0f; matrix.m[2, 1] = 0.0f; matrix.m[2, 2] = 1.0f; matrix.m[2, 3] = 0.0f;
   matrix.m[3, 0] = 0.0f; matrix.m[3, 1] = 0.0f; matrix.m[3, 2] = 0.0f; matrix.m[3, 3] = 1.0f;
  }

  public static VMatrix MatrixMultiply(VMatrix src1, VMatrix src2)
  {
   VMatrix dst = new VMatrix();
   dst.m[0,0] = src1.m[0,0] * src2.m[0,0] + src1.m[0,1] * src2.m[1,0] + src1.m[0,2] * src2.m[2,0] + src1.m[0,3] * src2.m[3,0];
   dst.m[0,1] = src1.m[0,0] * src2.m[0,1] + src1.m[0,1] * src2.m[1,1] + src1.m[0,2] * src2.m[2,1] + src1.m[0,3] * src2.m[3,1];
   dst.m[0,2] = src1.m[0,0] * src2.m[0,2] + src1.m[0,1] * src2.m[1,2] + src1.m[0,2] * src2.m[2,2] + src1.m[0,3] * src2.m[3,2];
   dst.m[0,3] = src1.m[0,0] * src2.m[0,3] + src1.m[0,1] * src2.m[1,3] + src1.m[0,2] * src2.m[2,3] + src1.m[0,3] * src2.m[3,3];

   dst.m[1,0] = src1.m[1,0] * src2.m[0,0] + src1.m[1,1] * src2.m[1,0] + src1.m[1,2] * src2.m[2,0] + src1.m[1,3] * src2.m[3,0];
   dst.m[1,1] = src1.m[1,0] * src2.m[0,1] + src1.m[1,1] * src2.m[1,1] + src1.m[1,2] * src2.m[2,1] + src1.m[1,3] * src2.m[3,1];
   dst.m[1,2] = src1.m[1,0] * src2.m[0,2] + src1.m[1,1] * src2.m[1,2] + src1.m[1,2] * src2.m[2,2] + src1.m[1,3] * src2.m[3,2];
   dst.m[1,3] = src1.m[1,0] * src2.m[0,3] + src1.m[1,1] * src2.m[1,3] + src1.m[1,2] * src2.m[2,3] + src1.m[1,3] * src2.m[3,3];

   dst.m[2,0] = src1.m[2,0] * src2.m[0,0] + src1.m[2,1] * src2.m[1,0] + src1.m[2,2] * src2.m[2,0] + src1.m[2,3] * src2.m[3,0];
   dst.m[2,1] = src1.m[2,0] * src2.m[0,1] + src1.m[2,1] * src2.m[1,1] + src1.m[2,2] * src2.m[2,1] + src1.m[2,3] * src2.m[3,1];
   dst.m[2,2] = src1.m[2,0] * src2.m[0,2] + src1.m[2,1] * src2.m[1,2] + src1.m[2,2] * src2.m[2,2] + src1.m[2,3] * src2.m[3,2];
   dst.m[2,3] = src1.m[2,0] * src2.m[0,3] + src1.m[2,1] * src2.m[1,3] + src1.m[2,2] * src2.m[2,3] + src1.m[2,3] * src2.m[3,3];

   dst.m[3,0] = src1.m[3,0] * src2.m[0,0] + src1.m[3,1] * src2.m[1,0] + src1.m[3,2] * src2.m[2,0] + src1.m[3,3] * src2.m[3,0];
   dst.m[3,1] = src1.m[3,0] * src2.m[0,1] + src1.m[3,1] * src2.m[1,1] + src1.m[3,2] * src2.m[2,1] + src1.m[3,3] * src2.m[3,1];
   dst.m[3,2] = src1.m[3,0] * src2.m[0,2] + src1.m[3,1] * src2.m[1,2] + src1.m[3,2] * src2.m[2,2] + src1.m[3,3] * src2.m[3,2];
   dst.m[3,3] = src1.m[3,0] * src2.m[0,3] + src1.m[3,1] * src2.m[1,3] + src1.m[3,2] * src2.m[2,3] + src1.m[3,3] * src2.m[3,3];
   return dst;
  }

  public Vector4 MatrixGetCol(int nCol)
  {
   System.Diagnostics.Debug.Assert((nCol >= 0) && (nCol <= 3));

   Vector4 vec;
   vec.x = m[0,nCol];
   vec.y = m[1,nCol];
   vec.z = m[2,nCol];
   vec.w = m[3,nCol];
   return vec;
  }

  public Vector4 MatrixGetRow(int nRow)
  {
   System.Diagnostics.Debug.Assert((nRow >= 0) && (nRow <= 3));
   Vector4 vec;
   vec.x = m[nRow, 0];
   vec.y = m[nRow, 1];
   vec.z = m[nRow, 2];
   vec.w = m[nRow, 3];
   return vec;
  }

  public static VMatrix GetSRTMatrix(Vector2 scale, float rotation, Vector2 center, Vector2 translation)
  {
   VMatrix mat = new VMatrix();
   VMatrix temp = new VMatrix();

   MatrixBuildScale(mat, scale.x, scale.y, 1.0f);
   MatrixBuildTranslation(temp, -center);
   mat = MatrixMultiply(temp, mat);
   MatrixBuildRotate(temp, rotation);
   mat = MatrixMultiply(temp, mat);
   MatrixBuildTranslation(temp, center.x + translation.x, center.y - translation.y, 0.0f);
   mat = MatrixMultiply(temp, mat);
   return mat;
  }
 }
}

调用方式：

VMatrix matrix = VMatrix.GetSRTMatrix(scale, -m_cur_rotate, center, translation + translationExtra);
m_CRTTexture.material.SetVector("_SRT0", matrix.MatrixGetRow(0));
m_CRTTexture.material.SetVector("_SRT1", matrix.MatrixGetRow(1));

shader使用：

Properties
{
 _SRT0("PatternSRT0", Vector) = (1, 1, 1, 1)
 _SRT1("PatternSRT1", Vector) = (1, 1, 1, 1)
}

Pass
{
 float4 _SRT0;
 float4 _SRT1;

 float4 get_pattern_color(float2 uv)
 {
 float2 uv2;
 uv2.x = dot(uv, _SRT0.xy) + _SRT0.w;
 uv2.y = dot(uv, _SRT1.xy) + _SRT1.w;
 return tex2D(_PatternTexture, uv2);
 }
}

感兴趣的可以自己试一试

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