Sign in to follow this  

A question about D3DDECLUSAGE

This topic is 3340 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

There's a paragraph explains D3DDECLUSAGE_POSITION : ------------------------------------------------------------ Position data ranging from (-1,-1) to (1,1). Use D3DDECLUSAGE_POSITION with a usage index of 0 to specify untransformed position for fixed function vertex processing and the n-patch tessellator. Use D3DDECLUSAGE_POSITION with a usage index of 1 to specify untransformed position in the fixed function vertex shader for vertex tweening. ---------------------------------------------------------------------- In DirectX SDK (August 2007) what's the meaning of "Position data ranging from (-1,-1) to (1,1). " ? is the position data in World coordinate? and is it a 3D vector? how could it range from (-1,-1) to (1,1) ??

Share this post


Link to post
Share on other sites
That description seems entirely wrong. You can use any range of values, and typically, yes, they are 3D. Those limits may apply to usage index 1, when using the n-patch tessellator. I have no idea how that system works.

Positions are usually given in object space, which can be moved to world space with the world matrix. This allows you to use the same mesh in multiple locations in the world, or to have the object move without modifying the vertex data.

Share this post


Link to post
Share on other sites

This topic is 3340 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this