Coordinate System

Coordinate System

• AvalonNewbie

  In Direct3D, there are no screen coordinates (like 400,300). You set up your scene in "world coordinates", and DirectX transforms those to screen coordinates for you when it renders the scene.
  
  

• Franco Robles

  Not true Daniel
  
  When you define your vertex format (FVF) you can specify D3DFVF_XYZRHW which tells D3D to use screen coords for the vertices instead of "model" coords. So you might have a vertex structure like:
  
  struct MYVERTEX
  {
      float x;    // 0 to MAXSCREENWIDTH
      float y;    // 0 to MAXSCREENHEIGHT
      float z;    // 0.0f
      float rhw;  // 1.0f
      D3DCOLOR colour; // 0xARGB
    };
  
  The rhw stands for "reciprocal of homogenous W" (obvious eh !) and should always be 1.0f. The z field is not used in screen coords and should be set to 0.0f. x and y are the standard Windows screen coords with x increasing left to right and y increasing top to bottom.
  
  Set your FVF with:
  
  DWORD D3DFVF_MYVERTEX = D3DFVF_XYZRHW | D3DFVF_DIFFUSE;
  pd3d9device->SetFVF(D3DFVF_MYVERTEX);
  
  The D3D9 SDK tutorial goes into this in more detail.
  
  20thCB
  
  
  
  
  

  
  

• Michael-Thomson

  Likewise, if you are using managed DX9, then you should also be able to use CustomVertex.Transformed for you vertices. They are supposed to already be transformed into screen coordinates for your display, 0,0 being upper left.
  
  They have the same structure as 20thCentury's MYVERTEX structure
  
  For a C# example, look at Tutorial #2 in the sdk.
  
  

• vc56522

  I have a question about this,
     is there a math formula that I can use to place objects in world space to make sure they are spaced out right, all the objects will be the same size.   
  
• Coordinate System