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# coordinate system

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2 replies to this topic

### #1Jerry.Mouse  Members

Posted 23 May 2014 - 08:44 AM

Hello,

I have a small problem. I have a small triangle - see attachments "coordinatesystem.bmp":

v[0].pose = SlimDX::Vector3( -0.5f, +0.0f, 0.0f );
v[0].color = 0x000fff; //

v[1].pose = SlimDX::Vector3( +2.5f, +0.0f, 0.0f );
v[1].color = 0x000fff; //

v[2].pose = SlimDX::Vector3( +0.0f, +1.5f, 0.0f );
v[2].color = 0x000fff; //

Unfortunately, this triangle is depicted reverse. +X axis is on the left side, -X axis in on the righ side, +Y is Top, -Y is bottom.
+Z heading to me, out of screen and -Z heading to screen. see the attachments.

I am using only these commands:

sl_device->SetTransform( SlimDX::Direct3D9::TransformState::View,
SlimDX::Matrix::LookAtLH( SlimDX::Vector3( 0.0f,  0.0f, 15.0f ), //
SlimDX::Vector3( 0.0f,  0.0f,  1.0f ),
SlimDX::Vector3( 0.0f, +1.0f,  0.0f ) ) );

sl_device->SetTransform( SlimDX::Direct3D9::TransformState::Projection,
SlimDX::Matrix::PerspectiveFovLH( (float)Math::PI / 2, 1.76795f, 0.1f, 100.0f) );

If I use these commands:

sl_device->SetTransform( SlimDX::Direct3D9::TransformState::View,
SlimDX::Matrix::LookAtLH( SlimDX::Vector3( 0.0f,  0.0f, 15.0f ), //
SlimDX::Vector3( 0.0f,  0.0f,  1.0f ),
SlimDX::Vector3( 0.0f, +1.0f,  0.0f ) ) );

sl_device->SetTransform( SlimDX::Direct3D9::TransformState::World,
SlimDX::Matrix::Translation( 0.0f, 0.0f, 0.0f ) *
SlimDX::Matrix::RotationY( 0.785f ) *
SlimDX::Matrix::RotationX( 0.785f ) *
SlimDX::Matrix::RotationZ( 0.785f )
);

sl_device->SetTransform( SlimDX::Direct3D9::TransformState::Projection,
SlimDX::Matrix::PerspectiveFovLH( (float)Math::PI / 2, 1.76795f, 0.1f, 100.0f) );

Situation is identical  see attachments "coordinatesystem2.bmp"

I supposed that SlimDX uses left-hand coordinate system. It is: +X is on the right side, -X is on the left side,+Y is top, -Y bottom,

What is wrong ? I have somewhat reversed coordinate system.

### #2Buckeye  GDNet+

Posted 23 May 2014 - 09:25 AM

+X axis is on the left side, -X axis in on the righ side, +Y is Top, -Y is bottom.
+Z heading to me, out of screen and -Z heading to screen

That's how you have the view matrix setup. Eyepoint along the +Z, looking at the origin. That puts the +X axis on the left in a LH system.

Try setting your view with Eye along -Z somewhere, looking at the origin.

EDIT: Not sure how you have your cullmode setup, but you have the vertices in ccw order.

Edited by Buckeye, 23 May 2014 - 09:27 AM.

Please don't PM me with questions. Post them in the forums for everyone's benefit, and I can embarrass myself publicly.

You don't forget how to play when you grow old; you grow old when you forget how to play.

### #3Jerry.Mouse  Members

Posted 23 May 2014 - 11:03 AM

Thanks. It helped.

this is correct:

sl_device->SetRenderState( SlimDX::Direct3D9::RenderState::CullMode, SlimDX::Direct3D9::Cull::None );
sl_device->SetRenderState( SlimDX::Direct3D9::RenderState::Lighting, false );

sl_device->SetTransform( SlimDX::Direct3D9::TransformState::View,
SlimDX::Matrix::LookAtLH( SlimDX::Vector3( 0.0f,  0.0f, -15.0f ), //
SlimDX::Vector3( 0.0f,  0.0f, +15.0f ),
SlimDX::Vector3( 0.0f, +1.0f,  0.0f ) ) );

sl_device->SetTransform( SlimDX::Direct3D9::TransformState::World,
SlimDX::Matrix::Translation( 0.0f, 0.0f, 0.0f ) *
SlimDX::Matrix::RotationY( +0.3f ) *
SlimDX::Matrix::RotationX( -0.2f ) *
SlimDX::Matrix::RotationZ( 0.0f )
);

+X is on the right side, +Y is top, +Z is in LCD monitor.

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Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.