'' This code has been created by Banu Cosmin aka Choko - 20 may 2000 '' and uses NeHe tutorials as a starting point (window initialization, '' texture loading, GL initialization and code for keypresses) - very good '' tutorials, Jeff. If anyone is interested about the presented algorithm '' please e-mail me at boct@romwest.ro '' '' Attention!!! This code is not for beginners. '' '' NeHe Productions ... http://nehe.gamedev.net '' ''------------------------------------------------------------------------------ '' Press ESC key to quit '' Use Arrow keys to spin object '' Use L, J, I, K, O & U keys to move light '' Use 4, 5, 6, 7, 8, & 9 keys to move Object '' Use A, D, W, S, E & Q keys to move Ball ''------------------------------------------------------------------------------ '' compile as: fbc -s gui lesson27.bas '' Setup our booleans const null = 0 #include once "GL/gl.bi" #include once "GL/glu.bi" #include once "fbgfx.bi" '' for Scan code constants #include once "crt.bi" #include once "3Dobject.bi" '' Header File For 3D Object Handling ''------------------------------------------------------------------------------ declare sub VMatMult(byval M as single ptr, byval v as single ptr) declare function InitGLObjects() as integer declare sub DrawGLRoom() ''------------------------------------------------------------------------------ '' The object loader fills this scene shared by the module draw routine. '' FB-LINTER: DISABLE-NEXT-LINE FBL301 dim shared as glObject obj '' Object dim as single xrot=0, xspeed=0 '' X Rotation & X Speed dim as single yrot=0, yspeed=0 '' Y Rotation & Y Speed dim as single LightPos(0 to 3) => {0.0, 5.0, -4.0, 1.0} '' Light Position dim as single LightAmb(0 to 3) => {0.2, 0.2, 0.2, 1.0} '' Ambient Light Values dim as single LightDif(0 to 3) => {0.6, 0.6, 0.6, 1.0} '' Diffuse Light Values dim as single LightSpc(0 to 3) => {-0.2, -0.2, -0.2, 1.0} '' Specular Light Values dim as single MatAmb(0 to 3) => {0.4, 0.4, 0.4, 1.0} '' Material - Ambient Values dim as single MatDif(0 to 3) => {0.2, 0.6, 0.9, 1.0} '' Material - Diffuse Values dim as single MatSpc(0 to 3) => {0.0, 0.0, 0.0, 1.0} '' Material - Specular Values dim as single MatShn(0) => {0.0} '' Material - Shininess dim as single ObjPos(0 to 2) => {-2.0, -2.0, -5.0} '' Object Position dim as GLUquadricObj ptr q '' Quadratic For Drawing A Sphere dim as single SpherePos(0 to 2) => {-4.0, -5.0, -6.0} dim Minv(0 to 15) as single dim as single wlp(0 to 3), lp(0 to 3) screen 19, 16, , FB.GFX_OPENGL or FB.GFX_STENCIL_BUFFER windowtitle "Banu Octavian & NeHe's Shadow Casting Tutorial" '' Set window title '' ReSizeGLScene glViewport 0, 0, 800, 600 '' Reset The Current Viewport glMatrixMode GL_PROJECTION '' Select The Projection Matrix glLoadIdentity '' Reset The Projection Matrix gluPerspective 45.0, 800/600, 0.001, 100.0 '' Calculate The Aspect Ratio Of The Window glMatrixMode GL_MODELVIEW '' Select The Modelview Matrix glLoadIdentity '' Reset The Projection Matrix '' All Setup For OpenGL Goes Here if (InitGLObjects()= 0) then end 1 '' Function For Initializing Our Object(s) glShadeModel(GL_SMOOTH) '' Enable Smooth Shading glClearColor(0.0, 0.0, 0.0, 0.5) '' Black Background glClearDepth(1.0) '' Depth Buffer Setup glClearStencil(0) '' Stencil Buffer Setup glEnable(GL_DEPTH_TEST) '' Enables Depth Testing glDepthFunc(GL_LEQUAL) '' The Type Of Depth Testing To Do glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST) '' Really Nice Perspective Calculations glLightfv(GL_LIGHT1, GL_POSITION, @LightPos(0)) '' Set Light1 Position glLightfv(GL_LIGHT1, GL_AMBIENT, @LightAmb(0)) '' Set Light1 Ambience glLightfv(GL_LIGHT1, GL_DIFFUSE, @LightDif(0)) '' Set Light1 Diffuse glLightfv(GL_LIGHT1, GL_SPECULAR, @LightSpc(0)) '' Set Light1 Specular glEnable(GL_LIGHT1) '' Enable Light1 glEnable(GL_LIGHTING) '' Enable Lighting glMaterialfv(GL_FRONT, GL_AMBIENT, @MatAmb(0)) '' Set Material Ambience glMaterialfv(GL_FRONT, GL_DIFFUSE, @MatDif(0)) '' Set Material Diffuse glMaterialfv(GL_FRONT, GL_SPECULAR, @MatSpc(0)) '' Set Material Specular glMaterialfv(GL_FRONT, GL_SHININESS, @MatShn(0)) '' Set Material Shininess glCullFace(GL_BACK) '' Set Culling Face To Back Face glEnable(GL_CULL_FACE) '' Enable Culling glClearColor(0.1, 1.0, 0.5, 1.0) '' Set Clear Color (Greenish Color) q = gluNewQuadric() '' Initialize Quadratic gluQuadricNormals(q, GL_SMOOTH) '' Enable Smooth Normal Generation gluQuadricTexture(q, GL_FALSE) '' Disable Auto Texture Coords do '' Clear Color Buffer, Depth Buffer, Stencil Buffer glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT or GL_STENCIL_BUFFER_BIT) glLoadIdentity() '' Reset Modelview Matrix glTranslatef(0.0, 0.0, -20.0) '' Zoom Into Screen 20 Units glLightfv(GL_LIGHT1, GL_POSITION, @LightPos(0)) '' Position Light1 glTranslatef(SpherePos(0), SpherePos(1), SpherePos(2)) '' Position The Sphere gluSphere(q, 1.5, 32, 16) '' Draw A Sphere '' calculate light's position relative to local coordinate system '' dunno if this is the best way to do it, but it actually works '' if u find another aproach, let me know ) '' we build the inversed matrix by doing all the actions in reverse order '' and with reverse parameters (notice -xrot, -yrot, -ObjPos[], etc.) glLoadIdentity() '' Reset Matrix glRotatef(-yrot, 0.0, 1.0, 0.0) '' Rotate By -yrot On Y Axis glRotatef(-xrot, 1.0, 0.0, 0.0) '' Rotate By -xrot On X Axis glGetFloatv(GL_MODELVIEW_MATRIX, @Minv(0)) '' Retrieve ModelView Matrix (Stores In Minv) lp(0) = LightPos(0) '' Store Light Position X In lp[0] lp(1) = LightPos(1) '' Store Light Position Y In lp[1] lp(2) = LightPos(2) '' Store Light Position Z In lp[2] lp(3) = LightPos(3) '' Store Light Direction In lp[3] VMatMult(@Minv(0), @lp(0)) '' We Store Rotated Light Vector In 'lp' Array glTranslatef(-ObjPos(0), -ObjPos(1), -ObjPos(2)) '' Move Negative On All Axis Based On ObjPos[] Values (X, Y, Z) glGetFloatv(GL_MODELVIEW_MATRIX, @Minv(0)) '' Retrieve ModelView Matrix From Minv wlp(0) = 0.0 '' World Local Coord X To 0 wlp(1) = 0.0 '' World Local Coord Y To 0 wlp(2) = 0.0 '' World Local Coord Z To 0 wlp(3) = 1.0 VMatMult(@Minv(0), @wlp(0)) '' We Store The Position Of The World Origin Relative To The '' Local Coord. System In 'wlp' Array lp(0) += wlp(0) '' Adding These Two Gives Us The lp(1) += wlp(1) '' Position Of The Light Relative To lp(2) += wlp(2) '' The Local Coordinate System glColor4f(0.7, 0.4, 0.0, 1.0) '' Set Color To An Orange glLoadIdentity() '' Reset Modelview Matrix glTranslatef(0.0, 0.0, -20.0) '' Zoom Into The Screen 20 Units DrawGLRoom() '' Draw The Room glTranslatef(ObjPos(0), ObjPos(1), ObjPos(2)) '' Position The Object glRotatef(xrot, 1.0, 0.0, 0.0) '' Spin It On The X Axis By xrot glRotatef(yrot, 0.0, 1.0, 0.0) '' Spin It On The Y Axis By yrot DrawGLObject(@obj) '' Procedure For Drawing The Loaded Object CastShadow(@obj, @lp(0)) '' Procedure For Casting The Shadow Based On The Silhouette glColor4f(0.7, 0.4, 0.0, 1.0) '' Set Color To Purplish Blue glDisable(GL_LIGHTING) '' Disable Lighting glDepthMask(GL_FALSE) '' Disable Depth Mask glTranslatef(lp(0), lp(1), lp(2)) '' Translate To Light's Position '' Notice We're Still In Local Coordinate System gluSphere(q, 0.2, 16, 8) '' Draw A Little Yellow Sphere (Represents Light) glEnable(GL_LIGHTING) '' Enable Lighting glDepthMask(GL_TRUE) '' Enable Depth Mask xrot += xspeed '' Increase xrot By xspeed yrot += yspeed '' Increase yrot By yspeed glFlush() '' Flush The OpenGL Pipeline '' Keyboard handlers '' Spin Object if MULTIKEY(FB.SC_LEFT) then yspeed -= 0.1 '' 'Arrow Left' Decrease yspeed if MULTIKEY(FB.SC_RIGHT) then yspeed += 0.1 '' 'Arrow Right' Increase yspeed if MULTIKEY(FB.SC_UP) then xspeed -= 0.1 '' 'Arrow Up' Decrease xspeed if MULTIKEY(FB.SC_DOWN) then xspeed += 0.1 '' 'Arrow Down' Increase xspeed '' Adjust Light's Position if MULTIKEY(FB.SC_L) then LightPos(0) += 0.05 '' 'L' Moves Light Right if MULTIKEY(FB.SC_J) then LightPos(0) -= 0.05 '' 'J' Moves Light Left if MULTIKEY(FB.SC_I) then LightPos(1) += 0.05 '' 'I' Moves Light Up if MULTIKEY(FB.SC_K) then LightPos(1) -= 0.05 '' 'K' Moves Light Down if MULTIKEY(FB.SC_O) then LightPos(2) += 0.05 '' 'O' Moves Light Toward Viewer if MULTIKEY(FB.SC_U) then LightPos(2) -= 0.05 '' 'U' Moves Light Away From Viewer '' Adjust Object's Position if MULTIKEY(FB.SC_6) then ObjPos(0) += 0.05 '' '6' Move Object Right if MULTIKEY(FB.SC_4) then ObjPos(0) -= 0.05 '' '4' Move Object Left if MULTIKEY(FB.SC_8) then ObjPos(1) += 0.05 '' '8' Move Object Up if MULTIKEY(FB.SC_5) then ObjPos(1) -= 0.05 '' '5' Move Object Down if MULTIKEY(FB.SC_9) then ObjPos(2) += 0.05 '' '9' Move Object Toward Viewer if MULTIKEY(FB.SC_7) then ObjPos(2) -= 0.05 '' '7' Move Object Away From Viewer '' Adjust Ball's Position if MULTIKEY(FB.SC_D) then SpherePos(0) += 0.05 '' 'D' Move Ball Right if MULTIKEY(FB.SC_A) then SpherePos(0) -= 0.05 '' 'A' Move Ball Left if MULTIKEY(FB.SC_W) then SpherePos(1) += 0.05 '' 'W' Move Ball Up if MULTIKEY(FB.SC_S) then SpherePos(1) -= 0.05 '' 'S' Move Ball Down if MULTIKEY(FB.SC_E) then SpherePos(2) += 0.05 '' 'E' Move Ball Toward Viewer if MULTIKEY(FB.SC_Q) then SpherePos(2) -= 0.05 '' 'Q' Move Ball Away From Viewer flip '' flip or crash if inkey = chr(255)+"k" then exit do '' exit if close box is clicked loop while MULTIKEY(FB.SC_ESCAPE) = 0 '' Empty keyboard buffer while INKEY <> "": wend end sub VMatMult(byval M as single ptr, byval v as single ptr) dim as single res(0 to 3) '' Hold Calculated Results res(0)=M[ 0]*v[0]+M[ 4]*v[1]+M[ 8]*v[2]+M[12]*v[3] res(1)=M[ 1]*v[0]+M[ 5]*v[1]+M[ 9]*v[2]+M[13]*v[3] res(2)=M[ 2]*v[0]+M[ 6]*v[1]+M[10]*v[2]+M[14]*v[3] res(3)=M[ 3]*v[0]+M[ 7]*v[1]+M[11]*v[2]+M[15]*v[3] v[0]=res(0) '' Results Are Stored Back In v[] v[1]=res(1) v[2]=res(2) v[3]=res(3) '' Homogenous Coordinate end sub '' Initialize Objects function InitGLObjects() as integer dim as uinteger i if (ReadObject(exepath + "/data/Object2.txt", @obj) = 0) then '' Read Object2 Into obj return false '' If Failed Return False end if SetConnectivity(@obj) '' Set Face To Face Connectivity for i=0 to obj.nPlanes-1 '' Loop Through All Object Planes CalcPlane(@obj, @obj.planes(i)) '' Compute Plane Equations For All Faces next return true '' Return True end function '' Draw The Room (Box) sub DrawGLRoom() glBegin(GL_QUADS) '' Begin Drawing Quads '' Floor glNormal3f(0.0, 1.0, 0.0) '' Normal Pointing Up glVertex3f(-10.0, -10.0, -20.0) '' Back Left glVertex3f(-10.0, -10.0, 20.0) '' Front Left glVertex3f( 10.0, -10.0, 20.0) '' Front Right glVertex3f( 10.0, -10.0, -20.0) '' Back Right '' Ceiling glNormal3f(0.0, -1.0, 0.0) '' Normal Point Down glVertex3f(-10.0, 10.0, 20.0) '' Front Left glVertex3f(-10.0, 10.0, -20.0) '' Back Left glVertex3f( 10.0, 10.0, -20.0) '' Back Right glVertex3f( 10.0, 10.0, 20.0) '' Front Right '' Front Wall glNormal3f(0.0, 0.0, 1.0) '' Normal Pointing Away From Viewer glVertex3f(-10.0, 10.0, -20.0) '' Top Left glVertex3f(-10.0, -10.0, -20.0) '' Bottom Left glVertex3f( 10.0, -10.0, -20.0) '' Bottom Right glVertex3f( 10.0, 10.0, -20.0) '' Top Right '' Back Wall glNormal3f(0.0, 0.0, -1.0) '' Normal Pointing Towards Viewer glVertex3f( 10.0, 10.0, 20.0) '' Top Right glVertex3f( 10.0, -10.0, 20.0) '' Bottom Right glVertex3f(-10.0, -10.0, 20.0) '' Bottom Left glVertex3f(-10.0, 10.0, 20.0) '' Top Left '' Left Wall glNormal3f(1.0, 0.0, 0.0) '' Normal Pointing Right glVertex3f(-10.0, 10.0, 20.0) '' Top Front glVertex3f(-10.0, -10.0, 20.0) '' Bottom Front glVertex3f(-10.0, -10.0, -20.0) '' Bottom Back glVertex3f(-10.0, 10.0, -20.0) '' Top Back '' Right Wall glNormal3f(-1.0, 0.0, 0.0) '' Normal Pointing Left glVertex3f( 10.0, 10.0, -20.0) '' Top Back glVertex3f( 10.0, -10.0, -20.0) '' Bottom Back glVertex3f( 10.0, -10.0, 20.0) '' Bottom Front glVertex3f( 10.0, 10.0, 20.0) '' Top Front glEnd() '' Done Drawing Quads end sub