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Does "rotate" function and "frustum" funtion should works in the same way when compare with mesa lib?? #33

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JieX opened this issue Jan 22, 2016 · 0 comments

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@JieX
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JieX commented Jan 22, 2016

As I can't reopen #31 , so i open a new issue.
I think there are still something wrong in transform functions.
When compare mesa code and es3 book code,
in "rotate" function, M(row, col) == m[row][col].
but in "frustum" funtions, _M(row, col) == m[col][row]_.
as mesa use 1-D array "M[ ]" stored in column-major, and "#define M(row,col) m[col * 4+row]"; es3 book source code use 2-D array "m[ ][ ]".

Does "rotate" function and "frustum" functions both should be either M(row, col) ==m[row][col] or M(row, col) == m[col][row]???
Or say another way, if we compare the data sequence of 2-D array "m[ ][ ]" which store row by row in the client memory, with the data sequence of 1-D array "M[ ]" in mesa in the client memory, they should be same?? And the data sequences are same when i compare "frustum" & "tranlation" & "scale" functions between mesa code and es3 book code, but "rotate" function doesn't, that's weird.

Mesa v10.6.5 rotate works:

      xx = x * x;
      yy = y * y;
      zz = z * z;
      xy = x * y;
      yz = y * z;
      zx = z * x;
      xs = x * s;
      ys = y * s;
      zs = z * s;
      one_c = 1.0F - c;

      /* We already hold the identity-matrix so we can skip some statements */
      M(0,0) = (one_c * xx) + c;
      M(0,1) = (one_c * xy) - zs;
      M(0,2) = (one_c * zx) + ys;
/*    M(0,3) = 0.0F; */

      M(1,0) = (one_c * xy) + zs;
      M(1,1) = (one_c * yy) + c;
      M(1,2) = (one_c * yz) - xs;
/*    M(1,3) = 0.0F; */

      M(2,0) = (one_c * zx) - ys;
      M(2,1) = (one_c * yz) + xs;
      M(2,2) = (one_c * zz) + c;
/*    M(2,3) = 0.0F; */
es3 book code rotate works:

      xx = x * x;
      yy = y * y;
      zz = z * z;
      xy = x * y;
      yz = y * z;
      zx = z * x;
      xs = x * sinAngle;
      ys = y * sinAngle;
      zs = z * sinAngle;
      oneMinusCos = 1.0f - cosAngle;

      rotMat.m[0][0] = ( oneMinusCos * xx ) + cosAngle;
      rotMat.m[0][1] = ( oneMinusCos * xy ) - zs;
      rotMat.m[0][2] = ( oneMinusCos * zx ) + ys;
      rotMat.m[0][3] = 0.0F;

      rotMat.m[1][0] = ( oneMinusCos * xy ) + zs;
      rotMat.m[1][1] = ( oneMinusCos * yy ) + cosAngle;
      rotMat.m[1][2] = ( oneMinusCos * yz ) - xs;
      rotMat.m[1][3] = 0.0F;

      rotMat.m[2][0] = ( oneMinusCos * zx ) - ys;
      rotMat.m[2][1] = ( oneMinusCos * yz ) + xs;
      rotMat.m[2][2] = ( oneMinusCos * zz ) + cosAngle;
      rotMat.m[2][3] = 0.0F;

      rotMat.m[3][0] = 0.0F;
      rotMat.m[3][1] = 0.0F;
      rotMat.m[3][2] = 0.0F;
      rotMat.m[3][3] = 1.0F;

Then in above codes, M(row, col) == m[row][col], The single data sequence in two matrixes are not in the same sequence in the client memory.

however, in frustum function,

Mesa v10.6.5 frustum works:

   x = (2.0F*nearval) / (right-left);
   y = (2.0F*nearval) / (top-bottom);
   a = (right+left) / (right-left);
   b = (top+bottom) / (top-bottom);
   c = -(farval+nearval) / ( farval-nearval);
   d = -(2.0F*farval*nearval) / (farval-nearval);  /* error? */

#define M(row,col)  m[col*4+row]
   M(0,0) = x;     M(0,1) = 0.0F;  M(0,2) = a;      M(0,3) = 0.0F;
   M(1,0) = 0.0F;  M(1,1) = y;     M(1,2) = b;      M(1,3) = 0.0F;
   M(2,0) = 0.0F;  M(2,1) = 0.0F;  M(2,2) = c;      M(2,3) = d;
   M(3,0) = 0.0F;  M(3,1) = 0.0F;  M(3,2) = -1.0F;  M(3,3) = 0.0F;
#undef M
es3 book code frustum works:

   frust.m[0][0] = 2.0f * nearZ / deltaX;
   frust.m[0][1] = frust.m[0][2] = frust.m[0][3] = 0.0f;

   frust.m[1][1] = 2.0f * nearZ / deltaY;
   frust.m[1][0] = frust.m[1][2] = frust.m[1][3] = 0.0f;

   frust.m[2][0] = ( right + left ) / deltaX;
   frust.m[2][1] = ( top + bottom ) / deltaY;
   frust.m[2][2] = - ( nearZ + farZ ) / deltaZ;
   frust.m[2][3] = -1.0f;

   frust.m[3][2] = -2.0f * nearZ * farZ / deltaZ;
   frust.m[3][0] = frust.m[3][1] = frust.m[3][3] = 0.0f;

in above codes, _M(row, col) == m[col][row] , as M(0,2) == m[2][0], M(1,2) == m[2][1], M(2,3) == m[3][2], ._ The single data sequence in two matrixes are in the same sequence in the client memory as 2-D array m[ ][ ] stores row by row.

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