WorldToScreen

004961B8   . 8D86 503F0000  LEA EAX,DWORD PTR DS:[ESI+3F50]                 // => World
004961BE   . 50             PUSH EAX
004961BF   . 8D8F BC010000  LEA ECX,DWORD PTR DS:[EDI+1BC]
004961C5   . 51             PUSH ECX
004961C6   . E8 D5470E00    CALL Engine-u.0057A9A0
004961CB   . 8D96 903F0000  LEA EDX,DWORD PTR DS:[ESI+3F90]                 // => View
004961D1   . 52             PUSH EDX
004961D2   . 8D47 7C        LEA EAX,DWORD PTR DS:[EDI+7C]
004961D5   . 50             PUSH EAX
004961D6   . E8 C5470E00    CALL Engine-u.0057A9A0
004961DB   . 8D8E D03F0000  LEA ECX,DWORD PTR DS:[ESI+3FD0]                 // => Projection
004961E1   . 51             PUSH ECX

#define D3DXMATRIX_WORLD   0x0049B56C
#define D3DXMATRIX_VIEW    0x0049B57F
#define D3DXMATRIX_PROJECTION   0x0049B58F

bool WorldToScreen( D3DXVECTOR3 WorldPos, D3DXVECTOR3 *ScreenPos, LPDIRECT3DDEVICE9 pDevice )
{ 
	D3DVIEWPORT9 ViewPort = { NULL };
	pDevice->GetViewport( &ViewPort );
	D3DXVec3Project( ScreenPos,
			 &WorldPos,
			 &ViewPort,
			 (D3DXMATRIX *)D3DXMATRIX_PROJECTION,
			 (D3DXMATRIX *)D3DXMATRIX_VIEW,
			 (D3DXMATRIX *)D3DXMATRIX_WORLD );

	return( ScreenPos->z < 1.0f );
}