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pick.cpp
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2001-10-31
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//-----------------------------------------------------------------------------
// File: Pick.cpp
//
// Desc: Example code showing how to do picking in D3D.
//
// Copyright (c) 1997-2001 Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#define STRICT
#include <math.h>
#include <stdio.h>
#include <D3DX8.h>
#include "D3DApp.h"
#include "D3DFont.h"
#include "D3DFile.h"
#include "D3DUtil.h"
#include "DXUtil.h"
#include "Resource.h"
struct D3DVERTEX
{
D3DXVECTOR3 p;
D3DXVECTOR3 n;
FLOAT tu, tv;
};
#define D3DFVF_VERTEX (D3DFVF_XYZ|D3DFVF_NORMAL|D3DFVF_TEX1)
struct INTERSECTION
{
DWORD dwFace; // mesh face that was intersected
FLOAT fBary1, fBary2; // barycentric coords of intersection
FLOAT fDist; // distance from ray origin to intersection
FLOAT tu, tv; // texture coords of intersection
};
// For simplicity's sake, we limit the number of simultaneously intersected
// triangles to 16
#define MAX_INTERSECTIONS 16
//-----------------------------------------------------------------------------
// Name: class CMyD3DApplication
// Desc: Application class. The base class (CD3DApplication) provides the
// generic functionality needed in all Direct3D samples. CMyD3DApplication
// adds functionality specific to this sample program.
//-----------------------------------------------------------------------------
class CMyD3DApplication : public CD3DApplication
{
CD3DFont* m_pFont; // Font for drawing text
CD3DFont* m_pFontSmall; // Font for drawing text
CD3DMesh* m_pObject; // Object to render
DWORD m_dwNumIntersections; // Number of faces intersected
INTERSECTION m_IntersectionArray[MAX_INTERSECTIONS]; // Intersection info
LPDIRECT3DVERTEXBUFFER8 m_pVB; // VB for picked triangles
BOOL m_bShowHelp; // Whether to show help
BOOL m_bUseD3DX; // Whether to use D3DXIntersect
BOOL m_bClosestOnly; // Whether to just get the closest intersection
// Internal member functions
HRESULT Pick();
BOOL IntersectTriangle( const D3DXVECTOR3& orig, const D3DXVECTOR3& dir,
D3DXVECTOR3& v0, D3DXVECTOR3& v1, D3DXVECTOR3& v2,
FLOAT* t, FLOAT* u, FLOAT* v );
HRESULT ConfirmDevice( D3DCAPS8*, DWORD, D3DFORMAT );
protected:
HRESULT OneTimeSceneInit();
HRESULT InitDeviceObjects();
HRESULT RestoreDeviceObjects();
HRESULT InvalidateDeviceObjects();
HRESULT DeleteDeviceObjects();
HRESULT Render();
HRESULT FrameMove();
HRESULT FinalCleanup();
public:
LRESULT MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam );
CMyD3DApplication();
};
//-----------------------------------------------------------------------------
// Name: WinMain()
// Desc: Entry point to the program. Initializes everything, and goes into a
// message-processing loop. Idle time is used to render the scene.
//-----------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR, INT )
{
CMyD3DApplication d3dApp;
if( FAILED( d3dApp.Create( hInst ) ) )
return 0;
return d3dApp.Run();
}
//-----------------------------------------------------------------------------
// Name: CMyD3DApplication()
// Desc: Application constructor. Sets attributes for the app.
//-----------------------------------------------------------------------------
CMyD3DApplication::CMyD3DApplication()
{
m_strWindowTitle = _T("Pick: D3D Picking Sample");
m_bUseDepthBuffer = TRUE;
m_bShowCursorWhenFullscreen = TRUE;
m_pFont = new CD3DFont( _T("Arial"), 12, D3DFONT_BOLD );
m_pFontSmall = new CD3DFont( _T("Arial"), 9, D3DFONT_BOLD );
m_pObject = new CD3DMesh();
m_dwNumIntersections = 0;
m_pVB = NULL;
m_bShowHelp = FALSE;
m_bUseD3DX = TRUE;
m_bClosestOnly = FALSE;
}
//-----------------------------------------------------------------------------
// Name: OneTimeSceneInit()
// Desc: Called during initial app startup, this function performs all the
// permanent initialization.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::OneTimeSceneInit()
{
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: Pick()
// Desc: Checks if mouse point hits geometry
// the scene.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::Pick()
{
HRESULT hr;
D3DXVECTOR3 vPickRayDir;
D3DXVECTOR3 vPickRayOrig;
m_dwNumIntersections = 0L;
// Get the pick ray from the mouse position
if( GetCapture() )
{
D3DXMATRIX matProj;
m_pd3dDevice->GetTransform( D3DTS_PROJECTION, &matProj );
POINT ptCursor;
GetCursorPos( &ptCursor );
ScreenToClient( m_hWnd, &ptCursor );
// Compute the vector of the pick ray in screen space
D3DXVECTOR3 v;
v.x = ( ( ( 2.0f * ptCursor.x ) / m_d3dsdBackBuffer.Width ) - 1 ) / matProj._11;
v.y = -( ( ( 2.0f * ptCursor.y ) / m_d3dsdBackBuffer.Height ) - 1 ) / matProj._22;
v.z = 1.0f;
// Get the inverse view matrix
D3DXMATRIX matView, m;
m_pd3dDevice->GetTransform( D3DTS_VIEW, &matView );
D3DXMatrixInverse( &m, NULL, &matView );
// Transform the screen space pick ray into 3D space
vPickRayDir.x = v.x*m._11 + v.y*m._21 + v.z*m._31;
vPickRayDir.y = v.x*m._12 + v.y*m._22 + v.z*m._32;
vPickRayDir.z = v.x*m._13 + v.y*m._23 + v.z*m._33;
vPickRayOrig.x = m._41;
vPickRayOrig.y = m._42;
vPickRayOrig.z = m._43;
}
// Get the picked triangle
if( GetCapture() )
{
LPD3DXBASEMESH pMesh = m_pObject->GetLocalMesh();
LPDIRECT3DVERTEXBUFFER8 pVB;
LPDIRECT3DINDEXBUFFER8 pIB;
pMesh->GetVertexBuffer( &pVB );
pMesh->GetIndexBuffer( &pIB );
WORD* pIndices;
D3DVERTEX* pVertices;
pIB->Lock( 0,0,(BYTE**)&pIndices, 0 );
pVB->Lock( 0,0,(BYTE**)&pVertices, 0 );
if( m_bUseD3DX )
{
// When calling D3DXIntersect, one can get just the closest intersection and not
// need to work with a D3DXBUFFER. Or, to get all intersections between the ray and
// the mesh, one can use a D3DXBUFFER to receive all intersections. We show both
// methods.
if( m_bClosestOnly )
{
// Collect only the closest intersection
BOOL bHit;
DWORD dwFace;
FLOAT fBary1, fBary2, fDist;
D3DXIntersect(pMesh, &vPickRayOrig, &vPickRayDir, &bHit, &dwFace, &fBary1, &fBary2, &fDist,
NULL, NULL);
if( bHit )
{
m_dwNumIntersections = 1;
m_IntersectionArray[0].dwFace = dwFace;
m_IntersectionArray[0].fBary1 = fBary1;
m_IntersectionArray[0].fBary2 = fBary2;
m_IntersectionArray[0].fDist = fDist;
}
else
{
m_dwNumIntersections = 0;
}
}
else
{
// Collect all intersections
BOOL bHit;
LPD3DXBUFFER pBuffer = NULL;
D3DXINTERSECTINFO* pIntersectInfoArray;
if( FAILED( hr = D3DXIntersect(pMesh, &vPickRayOrig, &vPickRayDir, &bHit, NULL, NULL, NULL, NULL,
&pBuffer, &m_dwNumIntersections) ) )
{
return hr;
}
if( m_dwNumIntersections > 0 )
{
pIntersectInfoArray = (D3DXINTERSECTINFO*)pBuffer->GetBufferPointer();
if( m_dwNumIntersections > MAX_INTERSECTIONS )
m_dwNumIntersections = MAX_INTERSECTIONS;
for( DWORD iIntersection = 0; iIntersection < m_dwNumIntersections; iIntersection++ )
{
m_IntersectionArray[iIntersection].dwFace = pIntersectInfoArray[iIntersection].FaceIndex;
m_IntersectionArray[iIntersection].fBary1 = pIntersectInfoArray[iIntersection].U;
m_IntersectionArray[iIntersection].fBary2 = pIntersectInfoArray[iIntersection].V;
m_IntersectionArray[iIntersection].fDist = pIntersectInfoArray[iIntersection].Dist;
}
}
}
}
else
{
// Not using D3DX
DWORD dwNumFaces = m_pObject->GetLocalMesh()->GetNumFaces();
FLOAT fBary1, fBary2;
FLOAT fDist;
for( DWORD i=0; i<dwNumFaces; i++ )
{
D3DXVECTOR3 v0 = pVertices[pIndices[3*i+0]].p;
D3DXVECTOR3 v1 = pVertices[pIndices[3*i+1]].p;
D3DXVECTOR3 v2 = pVertices[pIndices[3*i+2]].p;
// Check if the pick ray passes through this point
if( IntersectTriangle( vPickRayOrig, vPickRayDir, v0, v1, v2,
&fDist, &fBary1, &fBary2 ) )
{
if( !m_bClosestOnly || m_dwNumIntersections == 0 || fDist < m_IntersectionArray[0].fDist )
{
if( m_bClosestOnly )
m_dwNumIntersections = 0;
m_IntersectionArray[m_dwNumIntersections].dwFace = i;
m_IntersectionArray[m_dwNumIntersections].fBary1 = fBary1;
m_IntersectionArray[m_dwNumIntersections].fBary2 = fBary2;
m_IntersectionArray[m_dwNumIntersections].fDist = fDist;
m_dwNumIntersections++;
if( m_dwNumIntersections == MAX_INTERSECTIONS )
break;
}
}
}
}
// Now, for each intersection, add a triangle to m_pVB and compute texture coordinates
if( m_dwNumIntersections > 0 )
{
D3DVERTEX* v;
D3DVERTEX* vThisTri;
WORD* iThisTri;
D3DVERTEX v1, v2, v3;
INTERSECTION* pIntersection;
m_pVB->Lock( 0, 0, (BYTE**)&v, 0 );
for( DWORD iIntersection = 0; iIntersection < m_dwNumIntersections; iIntersection++ )
{
pIntersection = &m_IntersectionArray[iIntersection];
vThisTri = &v[iIntersection * 3];
iThisTri = &pIndices[3*pIntersection->dwFace];
// get vertices hit
vThisTri[0] = pVertices[iThisTri[0]];
vThisTri[1] = pVertices[iThisTri[1]];
vThisTri[2] = pVertices[iThisTri[2]];
// If all you want is the vertices hit, then you are done. In this sample, we
// want to show how to infer texture coordinates as well, using the BaryCentric
// coordinates supplied by D3DXIntersect
FLOAT dtu1 = vThisTri[1].tu - vThisTri[0].tu;
FLOAT dtu2 = vThisTri[2].tu - vThisTri[0].tu;
FLOAT dtv1 = vThisTri[1].tv - vThisTri[0].tv;
FLOAT dtv2 = vThisTri[2].tv - vThisTri[0].tv;
pIntersection->tu = vThisTri[0].tu + pIntersection->fBary1 * dtu1 + pIntersection->fBary2 * dtu2;
pIntersection->tv = vThisTri[0].tv + pIntersection->fBary1 * dtv1 + pIntersection->fBary2 * dtv2;
}
m_pVB->Unlock();
}
pVB->Unlock();
pIB->Unlock();
pVB->Release();
pIB->Release();
}
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: FrameMove()
// Desc: Called once per frame, the call is the entry point for animating
// the scene.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::FrameMove()
{
// Rotate the camera about the y-axis
D3DXVECTOR3 vFromPt = D3DXVECTOR3( 0.0f, 0.0f, 0.0f );
D3DXVECTOR3 vLookatPt = D3DXVECTOR3( 0.0f, 0.0f, 0.0f );
D3DXVECTOR3 vUpVec = D3DXVECTOR3( 0.0f, 1.0f, 0.0f );
vFromPt.x = -cosf(m_fTime/3.0f) * 4.0f;
vFromPt.y = 1.0f;
vFromPt.z = sinf(m_fTime/3.0f) * 4.0f;
D3DXMATRIX matView;
D3DXMatrixLookAtLH( &matView, &vFromPt, &vLookatPt, &vUpVec );
m_pd3dDevice->SetTransform( D3DTS_VIEW, &matView );
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: Render()
// Desc: Called once per frame, the call is the entry point for 3d
// rendering. This function sets up render states, clears the
// viewport, and renders the scene.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::Render()
{
// Set up the cursor
POINT ptCursor;
GetCursorPos( &ptCursor );
ScreenToClient( m_hWnd, &ptCursor );
m_pd3dDevice->SetCursorPosition( ptCursor.x, ptCursor.y, 0L );
// Check for picked triangles
Pick();
// Clear the viewport
m_pd3dDevice->Clear( 0L, NULL, D3DCLEAR_TARGET|D3DCLEAR_ZBUFFER,
0x000000ff, 1.0f, 0L );
// Begin the scene
if( SUCCEEDED( m_pd3dDevice->BeginScene() ) )
{
// Set render mode to lit, solid triangles
m_pd3dDevice->SetRenderState( D3DRS_FILLMODE, D3DFILL_SOLID );
m_pd3dDevice->SetRenderState( D3DRS_LIGHTING, TRUE );
// If a triangle is picked, draw it
if( m_dwNumIntersections > 0 )
{
// Draw the picked triangle
m_pd3dDevice->SetVertexShader( D3DFVF_VERTEX );
m_pd3dDevice->SetStreamSource( 0, m_pVB, sizeof(D3DVERTEX) );
m_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLELIST, 0, m_dwNumIntersections );
// Set render mode to unlit, wireframe triangles
m_pd3dDevice->SetRenderState( D3DRS_FILLMODE, D3DFILL_WIREFRAME );
m_pd3dDevice->SetRenderState( D3DRS_LIGHTING, FALSE );
}
// Render the mesh
m_pObject->Render( m_pd3dDevice );
// Output statistics
m_pFont->DrawText( 2, 0, D3DCOLOR_ARGB(255,255,255,0), m_strFrameStats );
m_pFont->DrawText( 2, 20, D3DCOLOR_ARGB(255,255,255,0), m_strDeviceStats );
// Output help
FLOAT yText = 40.0f;
if( m_bShowHelp )
{
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,255,255,255), _T("F1: Toggle Help") );
yText += 20.0f;
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,255,255,255), _T("F2: Change Device") );
yText += 20.0f;
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,255,255,255), _T("F3: Toggle D3DX Usage") );
yText += 20.0f;
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,255,255,255), _T("F4: Toggle All Hits") );
yText += 20.0f;
}
else
{
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,255,255,255), _T("Press F1 for Help") );
yText += 20.0f;
}
// Output info
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,255,255,255), m_bUseD3DX ? _T("Using D3DX") : _T("Not Using D3DX") );
yText += 20.0f;
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,255,255,255), m_bClosestOnly ? _T("Showing First Hit") : _T("Showing All Hits") );
yText += 20.0f;
CHAR strBuffer[90];
if( m_dwNumIntersections > 0 )
{
for( DWORD iIntersection = 0; iIntersection < m_dwNumIntersections; iIntersection++ )
{
INTERSECTION* pIntersection = &m_IntersectionArray[iIntersection];
sprintf( strBuffer, _T("Face=%d, tu=%3.02f, tv=%3.02f"), pIntersection->dwFace, pIntersection->tu, pIntersection->tv );
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,0,255,255), strBuffer );
yText += 20;
}
}
else
{
sprintf( strBuffer, _T("Use mouse to pick a polygon") );
m_pFontSmall->DrawText( 2, yText, D3DCOLOR_ARGB(255,0,255,255), strBuffer );
}
// End the scene.
m_pd3dDevice->EndScene();
}
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: InitDeviceObjects()
// Desc: Initialize scene objects.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::InitDeviceObjects()
{
// Restore the font
m_pFont->InitDeviceObjects( m_pd3dDevice );
m_pFontSmall->InitDeviceObjects( m_pd3dDevice );
if( FAILED( m_pObject->Create( m_pd3dDevice, _T("Tiger.x") ) ) )
return D3DAPPERR_MEDIANOTFOUND;
m_pObject->SetFVF( m_pd3dDevice, D3DFVF_VERTEX );
// Create the vertex buffer
DWORD dwNumVertices = MAX_INTERSECTIONS * 3;
if( FAILED( m_pd3dDevice->CreateVertexBuffer( dwNumVertices*sizeof(D3DVERTEX),
D3DUSAGE_WRITEONLY, D3DFVF_VERTEX,
D3DPOOL_MANAGED, &m_pVB ) ) )
{
return E_FAIL;
}
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: RestoreDeviceObjects()
// Desc: Initialize scene objects.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::RestoreDeviceObjects()
{
m_pFont->RestoreDeviceObjects();
m_pFontSmall->RestoreDeviceObjects();
// Restore device-memory objects for the mesh
m_pObject->RestoreDeviceObjects( m_pd3dDevice );
// Set up the textures
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLOROP, D3DTOP_MODULATE );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_MINFILTER, D3DTEXF_LINEAR );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_MAGFILTER, D3DTEXF_LINEAR );
// Set miscellaneous render states
m_pd3dDevice->SetRenderState( D3DRS_DITHERENABLE, FALSE );
m_pd3dDevice->SetRenderState( D3DRS_SPECULARENABLE, FALSE );
m_pd3dDevice->SetRenderState( D3DRS_ZENABLE, TRUE );
m_pd3dDevice->SetRenderState( D3DRS_AMBIENT, 0x00444444 );
// Set the world matrix
D3DXMATRIX matIdentity;
D3DXMatrixIdentity( &matIdentity );
m_pd3dDevice->SetTransform( D3DTS_WORLD, &matIdentity );
// Set the projection matrix
D3DXMATRIX matProj;
FLOAT fAspect = ((FLOAT)m_d3dsdBackBuffer.Width) / m_d3dsdBackBuffer.Height;
D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, fAspect, 1.0f, 100.0f );
m_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );
// Setup a material
D3DMATERIAL8 mtrl;
D3DUtil_InitMaterial( mtrl, 1.0f, 1.0f, 1.0f, 1.0f );
m_pd3dDevice->SetMaterial( &mtrl );
// Set up lighting states
D3DLIGHT8 light;
D3DUtil_InitLight( light, D3DLIGHT_DIRECTIONAL, 0.1f, -1.0f, 0.1f );
m_pd3dDevice->SetLight( 0, &light );
m_pd3dDevice->LightEnable( 0, TRUE );
m_pd3dDevice->SetRenderState( D3DRS_LIGHTING, TRUE );
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: InvalidateDeviceObjects()
// Desc:
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::InvalidateDeviceObjects()
{
m_pFont->InvalidateDeviceObjects();
m_pFontSmall->InvalidateDeviceObjects();
m_pObject->InvalidateDeviceObjects();
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: DeleteDeviceObjects()
// Desc: Called when the app is exiting, or the device is being changed,
// this function deletes any device dependent objects.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::DeleteDeviceObjects()
{
m_pFont->DeleteDeviceObjects();
m_pFontSmall->DeleteDeviceObjects();
m_pObject->Destroy();
SAFE_RELEASE( m_pVB );
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: FinalCleanup()
// Desc: Called before the app exits, this function gives the app the chance
// to cleanup after itself.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::FinalCleanup()
{
SAFE_DELETE( m_pFont );
SAFE_DELETE( m_pFontSmall );
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: ConfirmDevice()
// Desc: Called during device intialization, this code checks the device
// for some minimum set of capabilities
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::ConfirmDevice( D3DCAPS8* pCaps, DWORD dwBehavior,
D3DFORMAT Format )
{
if( dwBehavior & D3DCREATE_PUREDEVICE )
return E_FAIL; // GetTransform doesn't work on PUREDEVICE
// If this is a TnL device, make sure it supports directional lights
if( (dwBehavior & D3DCREATE_HARDWARE_VERTEXPROCESSING ) ||
(dwBehavior & D3DCREATE_MIXED_VERTEXPROCESSING ) )
{
if( !(pCaps->VertexProcessingCaps & D3DVTXPCAPS_DIRECTIONALLIGHTS ) )
return E_FAIL;
}
return S_OK;
}
//-----------------------------------------------------------------------------
// Name: MsgProc()
// Desc: Overrrides the main WndProc, so the sample can do custom message
// handling (e.g. processing mouse, keyboard, or menu commands).
//-----------------------------------------------------------------------------
LRESULT CMyD3DApplication::MsgProc( HWND hWnd, UINT msg, WPARAM wParam,
LPARAM lParam )
{
switch( msg )
{
case WM_LBUTTONDOWN:
// User pressed left mouse button
SetCapture( hWnd );
break;
case WM_LBUTTONUP:
// The user released the left mouse button
ReleaseCapture();
break;
case WM_COMMAND:
if( LOWORD(wParam) == IDM_HELP )
m_bShowHelp = !m_bShowHelp;
if( LOWORD(wParam) == IDM_TOGGLED3DX )
m_bUseD3DX = !m_bUseD3DX;
else if( LOWORD(wParam) == IDM_TOGGLEALLHITS )
m_bClosestOnly = !m_bClosestOnly;
break;
}
return CD3DApplication::MsgProc( hWnd, msg, wParam, lParam );
}
//-----------------------------------------------------------------------------
// Name: IntersectTriangle()
// Desc: Given a ray origin (orig) and direction (dir), and three vertices of
// of a triangle, this function returns TRUE and the interpolated texture
// coordinates if the ray intersects the triangle
//-----------------------------------------------------------------------------
BOOL CMyD3DApplication::IntersectTriangle( const D3DXVECTOR3& orig,
const D3DXVECTOR3& dir, D3DXVECTOR3& v0,
D3DXVECTOR3& v1, D3DXVECTOR3& v2,
FLOAT* t, FLOAT* u, FLOAT* v )
{
// Find vectors for two edges sharing vert0
D3DXVECTOR3 edge1 = v1 - v0;
D3DXVECTOR3 edge2 = v2 - v0;
// Begin calculating determinant - also used to calculate U parameter
D3DXVECTOR3 pvec;
D3DXVec3Cross( &pvec, &dir, &edge2 );
// If determinant is near zero, ray lies in plane of triangle
FLOAT det = D3DXVec3Dot( &edge1, &pvec );
D3DXVECTOR3 tvec;
if( det > 0 )
{
tvec = orig - v0;
}
else
{
tvec = v0 - orig;
det = -det;
}
if( det < 0.0001f )
return FALSE;
// Calculate U parameter and test bounds
*u = D3DXVec3Dot( &tvec, &pvec );
if( *u < 0.0f || *u > det )
return FALSE;
// Prepare to test V parameter
D3DXVECTOR3 qvec;
D3DXVec3Cross( &qvec, &tvec, &edge1 );
// Calculate V parameter and test bounds
*v = D3DXVec3Dot( &dir, &qvec );
if( *v < 0.0f || *u + *v > det )
return FALSE;
// Calculate t, scale parameters, ray intersects triangle
*t = D3DXVec3Dot( &edge2, &qvec );
FLOAT fInvDet = 1.0f / det;
*t *= fInvDet;
*u *= fInvDet;
*v *= fInvDet;
return TRUE;
}