Now A5 has me stumped.

[jkhippie]

This is the second tutorial in a row that's left me with some error I just can't see. All was good until I changed PolyClosed::Draw to use the matrices. After that I just get a blank screen when I run it. I changed Draw back to the way it was and it worked fine.
Thanks for any help.

a5 blank screen.zip

(639.08 KiB) Downloaded 160 times

[MrGodin]

just from a quick glance in PolyClosed::Draw you have..
Mat3 trans = Mat3::Translation ( pos ) * Mat3::Rotation ( angle ) * Mat3::Scaling ( scale );
where as i believe it should be ..
Mat3 trans = Mat3::Rotation ( angle ) * Mat3::Scaling ( scale ) *Mat3::Translation ( pos ) ;
i do believe the translation should be last
hope it helps

[jkhippie]

While trying to track this down, I noticed a couple typos. Typos corrected, problem persists.

[albinopapa]

I know you said you found a few typos, but you didn't upload the corrected project. Here are the problems I found so far.

Code: Select all

Vec2::operator*(const _Vec2<T> rhs ) const
{
// 
	_Vec2<T> result;
	result.x = elements [ 0 ][ 0 ] * rhs.x + elements [ 0 ][ 1 ] * rhs.y + elements [ 0 ][ 2 ];
	result.x = elements [ 1 ][ 0 ] * rhs.x + elements [ 1 ][ 1 ] * rhs.y + elements [ 1 ][ 2 ];
	return result;
}

	_Mat3 operator *( const _Mat3& rhs ) const
	{
		_Mat3 result;
		for ( int j = 0; j < 3; ++j )
		{
			for ( int k = 0; k < 3; ++k )
			{
				T sum = ( T )0.0;
				for ( int i = 0; i < 3; ++i )
				{
					// There is a problem here, you are looping through i and j
					// and when you are done with i you increment k, but don't do
					// anything with it here, which means you are looping through the same 
					// rows and colums.
					// should be.
					// sum += elements [ j ][ i ] * rhs.elements [ i ][ k ];
					sum += elements [ j ][ i ] * rhs.elements [ i ][ j ];
				}
				result.elements [ j ][ k ] = sum;
			}
		}
		return result;
	}

Both are part of the Mat3 class.

[jkhippie]

Yeah, ap, those were the two. They had no impact on my blankness of screen. When I had the Draw function using .Rotation(angle)... it was fine, but when I changed it to trans * ... all I got was a blank screen.

[albinopapa]

It works fine for me with the matrices in draw function

Code: Select all

	void Draw ( Vec2 pos, float angle, float scale, D3DGraphics& gfx ) const
	{
		Mat3 trans = Mat3::Translation ( pos ) * Mat3::Rotation ( angle ) * Mat3::Scaling ( scale );
		for ( auto i = vertices.begin (), end = vertices.end () - 1; i != end; ++i )
		{
			gfx.DrawLineClip(trans * (*i), trans * (*(i + 1)), color);
		}

		gfx.DrawLineClip(trans * vertices.back(), trans * vertices.front(), color);
	}

[jkhippie]

I reset my code to the way it was after A4 and went through A5 again. This time it worked. I can't say where I did anything differently, though I must have done. Anyway, thanks ap.