Ray tracing算法第二步-（Phong, Mirrors and Shadows）

// ----------------------------------------------------------- // raytracer.cpp // 2004 - Jacco Bikker - jacco@bik5.com - www.bik5.com - <>< // ----------------------------------------------------------- #include "raytracer.h" #include "scene.h" #include "common.h" #include "windows.h" #include "winbase.h" namespace Raytracer { Ray::Ray( vector3& a_Origin, vector3& a_Dir ) : m_Origin( a_Origin ), m_Direction( a_Dir ) { } Engine::Engine() { m_Scene = new Scene(); } Engine::~Engine() { delete m_Scene; } // ----------------------------------------------------------- // Engine::SetTarget // Sets the render target canvas // ----------------------------------------------------------- void Engine::SetTarget( Pixel* a_Dest, int a_Width, int a_Height ) { // set pixel buffer address & size m_Dest = a_Dest; m_Width = a_Width; m_Height = a_Height; } // ----------------------------------------------------------- // Engine::Raytrace // Naive ray tracing: Intersects the ray with every primitive // in the scene to determine the closest intersection // ----------------------------------------------------------- Primitive* Engine::Raytrace( Ray& a_Ray, Color& a_Acc, int a_Depth, float a_RIndex, float& a_Dist ) { if (a_Depth > TRACEDEPTH) return 0; // trace primary ray a_Dist = 1000000.0f; vector3 pi; Primitive* prim = 0; int result; // find the nearest intersection for ( int s = 0; s < m_Scene->GetNrPrimitives(); s++ ) { Primitive* pr = m_Scene->GetPrimitive( s ); int res; if (res = pr->Intersect( a_Ray, a_Dist )) { prim = pr; result = res; // 0 = miss, 1 = hit, -1 = hit from inside primitive } } // no hit, terminate ray if (!prim) return 0; // handle intersection if (prim->IsLight()) { // we hit a light, stop tracing a_Acc = Color( 1, 1, 1 ); } else { // determine color at point of intersection pi = a_Ray.GetOrigin() + a_Ray.GetDirection() * a_Dist; // trace lights for ( int l = 0; l < m_Scene->GetNrPrimitives(); l++ ) { Primitive* p = m_Scene->GetPrimitive( l ); if (p->IsLight()) { Primitive* light = p; // handle point light source float shade = 1.0f; if (light->GetType() == Primitive::SPHERE) { vector3 L = ((Sphere*)light)->GetCentre() - pi; float tdist = LENGTH( L ); L *= (1.0f / tdist); Ray r = Ray( pi + L * EPSILON, L ); for ( int s = 0; s < m_Scene->GetNrPrimitives(); s++ ) { Primitive* pr = m_Scene->GetPrimitive( s ); if ((pr != light) && (pr->Intersect( r, tdist ))) { shade = 0; break; } } } // calculate diffuse shading vector3 L = ((Sphere*)light)->GetCentre() - pi; NORMALIZE( L ); vector3 N = prim->GetNormal( pi ); if (prim->GetMaterial()->GetDiffuse() > 0) { float dot = DOT( L, N ); if (dot > 0) { float diff = dot * prim->GetMaterial()->GetDiffuse() * shade; // add diffuse component to ray color a_Acc += diff * light->GetMaterial()->GetColor() * prim->GetMaterial()->GetColor(); } } // determine specular component if (prim->GetMaterial()->GetSpecular() > 0) { // point light source: sample once for specular highlight vector3 V = a_Ray.GetDirection(); vector3 R = L - 2.0f * DOT( L, N ) * N; float dot = DOT( V, R ); if (dot > 0) { float spec = powf( dot, 20 ) * prim->GetMaterial()->GetSpecular() * shade; // add specular component to ray color a_Acc += spec * light->GetMaterial()->GetColor(); } } } } // calculate reflection float refl = prim->GetMaterial()->GetReflection(); if (refl > 0.0f) { vector3 N = prim->GetNormal( pi ); vector3 R = a_Ray.GetDirection() - 2.0f * DOT( a_Ray.GetDirection(), N ) * N; if (a_Depth < TRACEDEPTH) { Color rcol( 0, 0, 0 ); float dist; Raytrace( Ray( pi + R * EPSILON, R ), rcol, a_Depth + 1, a_RIndex, dist ); a_Acc += refl * rcol * prim->GetMaterial()->GetColor(); } } } // return pointer to primitive hit by primary ray return prim; } // ----------------------------------------------------------- // Engine::InitRender // Initializes the renderer, by resetting the line / tile // counters and precalculating some values // ----------------------------------------------------------- void Engine::InitRender() { // set firts line to draw to m_CurrLine = 20; // set pixel buffer address of first pixel m_PPos = 20 * m_Width; // screen plane in world space coordinates m_WX1 = -4, m_WX2 = 4, m_WY1 = m_SY = 3, m_WY2 = -3; // calculate deltas for interpolation m_DX = (m_WX2 - m_WX1) / m_Width; m_DY = (m_WY2 - m_WY1) / m_Height; m_SY += 20 * m_DY; // allocate space to store pointers to primitives for previous line m_LastRow = new Primitive*[m_Width]; memset( m_LastRow, 0, m_Width * 4 ); } // ----------------------------------------------------------- // Engine::Render // Fires rays in the scene one scanline at a time, from left // to right // ----------------------------------------------------------- bool Engine::Render() { // render scene vector3 o( 0, 0, -5 ); // initialize timer int msecs = GetTickCount(); // reset last found primitive pointer Primitive* lastprim = 0; // render remaining lines for ( int y = m_CurrLine; y < (m_Height - 20); y++ ) { m_SX = m_WX1; // render pixels for current line for ( int x = 0; x < m_Width; x++ ) { // fire primary ray Color acc( 0, 0, 0 ); vector3 dir = vector3( m_SX, m_SY, 0 ) - o; NORMALIZE( dir ); Ray r( o, dir ); float dist; Primitive* prim = Raytrace( r, acc, 1, 1.0f, dist ); int red = (int)(acc.r * 256); int green = (int)(acc.g * 256); int blue = (int)(acc.b * 256); if (red > 255) red = 255; if (green > 255) green = 255; if (blue > 255) blue = 255; m_Dest[m_PPos++] = (red << 16) + (green << 8) + blue; m_SX += m_DX; } m_SY += m_DY; // see if we've been working to long already if ((GetTickCount() - msecs) > 100) { // return control to windows so the screen gets updated m_CurrLine = y + 1; return false; } } // all done return true; } }; // namespace Raytracer