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digitalmars.D.learn - setting statically sized multi-dimensional arrays

reply Spacen Jasset <spacenjasset yahoo.co.uk> writes:
I have function below where I try to set a float[4][4] using array 
syntax. This doesn't work. Am I doing it wrongly, or is this not 
supported in dmd version 1? I seem to remember seeing something about 
this but can't remember where.



void MakeRotationAboutX(float[4][4] m, float angle)
{
     m[] = [[1f, 0, 0, 0],
            [0, cos(angle * PI / 180), sin(angle * PI / 180), 0],
            [0, -sin(angle * PI / 180), cos(angle * PI / 180), 0],
            [0, 0, 0, 1]];
}

main.d:501: Error: cannot implicitly convert expression
..lots of stuff..
of type float[][4u] to float[4u]
Command /usr/bin/rebuild returned with code 256, aborting.
Jan 21 2008
next sibling parent reply Ary Borenszweig <ary esperanto.org.ar> writes:
Spacen Jasset escribió:

 I have function below where I try to set a float[4][4] using array 
 syntax. This doesn't work. Am I doing it wrongly, or is this not 
 supported in dmd version 1? I seem to remember seeing something about 
 this but can't remember where.
 
 
 
 void MakeRotationAboutX(float[4][4] m, float angle)
 {
     m[] = [[1f, 0, 0, 0],
            [0, cos(angle * PI / 180), sin(angle * PI / 180), 0],
            [0, -sin(angle * PI / 180), cos(angle * PI / 180), 0],
            [0, 0, 0, 1]];
 }
 
 main.d:501: Error: cannot implicitly convert expression
 ..lots of stuff..
 of type float[][4u] to float[4u]
 Command /usr/bin/rebuild returned with code 256, aborting.



Try putting the "f" suffix on the first zeros in the second, third and 
foruth rows, too. It works for me:

import std.math;

void MakeRotationAboutX(float[4][4] m, float angle)
{
     m[] = [[1f, 0, 0, 0],
            [0f, cos(angle * PI / 180), sin(angle * PI / 180), 0],
            [0f, -sin(angle * PI / 180), cos(angle * PI / 180), 0],
            [0f, 0, 0, 1]];
}
Jan 21 2008
parent Spacen Jasset <spacenjassset yahoo.co.uk> writes:
Ary Borenszweig wrote:

 Spacen Jasset escribió:

 I have function below where I try to set a float[4][4] using array 
 syntax. This doesn't work. Am I doing it wrongly, or is this not 
 supported in dmd version 1? I seem to remember seeing something about 
 this but can't remember where.



 void MakeRotationAboutX(float[4][4] m, float angle)
 {
     m[] = [[1f, 0, 0, 0],
            [0, cos(angle * PI / 180), sin(angle * PI / 180), 0],
            [0, -sin(angle * PI / 180), cos(angle * PI / 180), 0],
            [0, 0, 0, 1]];
 }

 main.d:501: Error: cannot implicitly convert expression
 ..lots of stuff..
 of type float[][4u] to float[4u]
 Command /usr/bin/rebuild returned with code 256, aborting.



 Try putting the "f" suffix on the first zeros in the second, third and 
 foruth rows, too. It works for me:
 
 import std.math;
 
 void MakeRotationAboutX(float[4][4] m, float angle)
 {
     m[] = [[1f, 0, 0, 0],
            [0f, cos(angle * PI / 180), sin(angle * PI / 180), 0],
            [0f, -sin(angle * PI / 180), cos(angle * PI / 180), 0],
            [0f, 0, 0, 1]];
 }




It still fails with the same error, I did try adding the 'f' suffix, and 
it's probably needed, but that didn't fix it.

I have:

On windows:
Digital Mars D Compiler v1.015
Copyright (c) 1999-2007 by Digital Mars written by Walter Bright


And on linux:

gdc (GCC) 4.1.3 20070831 (prerelease gdc 0.25, using dmd 1.021) (Ubuntu 
0.25-4.1.2-16ubuntu1)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Jan 22 2008
prev sibling parent reply Hoenir <mrmocool gmx.de> writes:
Spacen Jasset schrieb:

 void MakeRotationAboutX(float[4][4] m, float angle)
 {
     m[] = [[1f, 0, 0, 0],
            [0, cos(angle * PI / 180), sin(angle * PI / 180), 0],
            [0, -sin(angle * PI / 180), cos(angle * PI / 180), 0],
            [0, 0, 0, 1]];
 }



will get inlined by the compiler so there's no efficiency loss.

btw you rotate clockwise, is this intented?
Jan 22 2008
next sibling parent reply Hoenir <mrmocool gmx.de> writes:
Oh and yet another thing: angle is in degrees, why is it a float?
Jan 22 2008
parent reply Bill Baxter <dnewsgroup billbaxter.com> writes:
Hoenir wrote:

 Oh and yet another thing: angle is in degrees, why is it a float?



Maybe he wants better than 1:360 precision?

--bb
Jan 22 2008
parent Hoenir <mrmocool gmx.de> writes:
Bill Baxter schrieb:

 Maybe he wants better than 1:360 precision?
Jan 22 2008
prev sibling parent reply Bill Baxter <dnewsgroup billbaxter.com> writes:
Hoenir wrote:

 Spacen Jasset schrieb:

 void MakeRotationAboutX(float[4][4] m, float angle)
 {
     m[] = [[1f, 0, 0, 0],
            [0, cos(angle * PI / 180), sin(angle * PI / 180), 0],
            [0, -sin(angle * PI / 180), cos(angle * PI / 180), 0],
            [0, 0, 0, 1]];
 }



 will get inlined by the compiler so there's no efficiency loss.
 
 btw you rotate clockwise, is this intented?



Unless he's using row vectors and  v' = v * R
Or storing the matrix in column major format for use with Fortran and/or 
OpenGL (most likely).

--bb
Jan 22 2008
parent Hoenir <mrmocool gmx.de> writes:
Bill Baxter schrieb:

 Unless he's using row vectors and  v' = v * R
 Or storing the matrix in column major format for use with Fortran and/or 
 OpenGL (most likely).
Jan 22 2008