.TH Animation 6 "IRIT Version 7.0" .SH NAME Animation The animation tool adds the capability of animating objects using forward kinematics, exploiting animation curves. Each object has different attributes, that prescribe its motion, scale, and visibility as a function of time. Every attribute has a name, which designates it's role. For instance an attribute animation curve named MOV_X describes a translation motion along the X axis. .SH How to create animation curves in IRIT Let OBJ be an object in IRIT to animate. Animation curves are either scalar (E1/P1) curves or three dimensional (E3/P3) curves with one of the following name prefixes: MOV_X, MOV_Y, MOV_Z Translation along one axis MOV_XYZ Arbitrary translation along all three axes ROT_X, ROT_Y, ROT_Z Rotating around a single axis (degrees) SCL_X, SCL_Y, SCL_Z Scale along a single axis SCL Global scale VISIBLE Visibility The visibility curve is a scalar curve that enables the display of the object if the visibility curve is positive at time t and disables the display (hide) the object if the visibility curve is negative at time t. The animation curves are all attached as an attribute named "animation" to the object OBJ. Example: mov_x = cbezier( ctlpt( E1, 0.0 ), ctlpt( E1, 1.0 ) ); scl = cbezier( ctlpt( E1, 1.0 ), ctlpt( E1, 0.1 ) ); rot_y = cbezier( ctlpt( E1, 0.0 ), ctlpt( E1, 0.0 ) ); ctlpt( E1, 360.0 ) ); attrib(OBJ, "animation", list( mov_x, scl, rot_y ) ); To animate OBJ between time zero and one (Bezier curves are always between zero and one), by moving it a unit size in the X direction, scaling it to %10 of its original size and rotating it at increasing angular speed from zero to 360 degrees. OBJ can now be save into a file or displayed via one of the regular viewing commands in IRIT (i.e. VIEWOBJ). Animation is not always between zero and one. To that end, one can apply the CREPARAM function to modify the parametric domain of the animation curve. The convention is that if the time is below the starting value of the parametric domain, the starting value of the curve is used. Similarly if the time is beyond the end of the parameter domain of the animation curve, the end value of the animation curve is used. Example: CREPARAM( mov_x, 3.0, 5.0 ); to set the time of the motion in the x axis to be from t = 3 to t = 5. for t < 3, mov_x(3) is used, and for t > 5, mov_x(5) is employed. the animation curves are regular objects in the IRIT system. Hence, only one object named mov_x or scl can exist at one time. If you create a new object named mov_x, the old one is overwritten! To preserve old animation curves you can detach the old ones by executing 'free(mov_x)' that removes the object named mov_x from IRIT's object list but not from its previous used locations within other list objects, if any. A different way to it call this animation curves mov_x1, mov_x2 etc. as only the prefix of the name is verified. For example: mov_x = cbezier( ctlpt( E1, 0.0 ), ctlpt( E1, 1.0 ) ); attrib(obj1, "animation", list( mov_x ) ); free(mov_x); mov_x1 = cbezier( ctlpt( E1, 2.0 ), ctlpt( E1, 3.0 ) ); mov_x2 = cbezier( ctlpt( E1, 2.0 ), ctlpt( E1, 3.0 ) ); attrib(obj2, "animation", list( mov_x1, mov_x2 ) ); free(mov_x); notice the way we have two animation curves translating obj2 in x. This is somewhat artificial but might make more sense if other transformations would appear in between. .SH A more complete animation example a = box( vector( 0, 0, 0 ), 1, 1, 1 ); b = box( vector( 0, 0, 0 ), 1, 1, 1 ); c = box( vector( 0, 0, 0 ), 1, 1, 1 ); d = sphere( vector( 0, 0, 0), 0.7 ); pt0 = ctlpt( e1, 0.0 ); pt1 = ctlpt( e1, 1.0 ); pt2 = ctlpt( e1, 2.0 ); pt6 = ctlpt( e1, 6.0 ); pt360 = ctlpt( e1, 360.0 ); pt10 = ctlpt( e1, -4.0 ); pt11 = ctlpt( e1, 1.0 ); pt12 = ctlpt( e1, 4.0 ); pt13 = ctlpt( e1, -1.0 ); visible = creparam( cbezier( list( pt10, pt11 ) ), 0.0, 5.0 ); mov_x = creparam( cbezier( list( pt0, pt6, pt2 ) ), 0.0, 1.2 ); mov_y = mov_x; mov_z = mov_x; rot_x = creparam( cbspline( 2, list( pt0, pt360, pt0 ), list( KV_OPEN ) ), 1.2, 2.5 ); rot_y = rot_x; rot_z = rot_x; scl = creparam( cbezier( list( pt1, pt2, pt1, pt2, pt1 ) ), 2.5, 4.0 ); scl_x = scl; scl_y = scl; scl_z = scl; mov_xyz = creparam( circle( vector( 0, 0, 0 ), 2.0 ), 4.0, 5.0 ); attrib( d, "animation", list( mov_xyz, visible ) ); free( visible ); visible = creparam( cbezier( list( pt12, pt13 ) ), 0.0, 5.0 ); attrib( a, "animation", list( rot_x, mov_x, scl, scl_x, visible ) ); attrib( b, "animation", list( rot_y, mov_y, scl, scl_y, visible ) ); attrib( c, "animation", list( rot_z, mov_z, scl, scl_z, visible ) ); color( a, red ); color( b, green ); color( c, blue ); color( d, cyan ); demo = list( a, b, c, d ); interact( demo ); viewanim( 0, 5, 0.01 ); In this example, we create four objects, three cubes and one sphere. Animation curves to translate the three cubes along the three axes for the time period of t = 0 to t = 1.2 are created. Rotation curves to rotate the three cubes along the three axes are then created for time period of t = 1.2 to t = 2.5. Finally, for the time period of t = 2.5 to t = 4.0. the cubes are (not only) unifomly scaled. For the time period of t = 4 to t = 5, the cubes become invisible and the sphere, that becomes visible, is rotated along a circle of radius 2. .SH Another complete animation example This example demonstrates the ability to put "animation" attributes on internal nodes of a hierarchy, affecting the entire set of objects in the hierachy. Herein, we present an robotic arm with three edges and two joints. BoxLength = 2; BoxWidth = 2; BoxHeight = 10; LowerBox = box( vector( -BoxLength / 2, -BoxWidth / 2, 0 ), BoxLength, BoxWidth, BoxHeight); MiddleBox = box( vector( -BoxLength / 2, -BoxWidth / 2, 0 ), BoxLength, BoxWidth, BoxHeight); UpperBox = box( vector( -BoxLength / 2, -BoxWidth / 2, 0 ), BoxLength, BoxWidth, BoxHeight); Cn1 = cone( vector( 0, 0, 0 ), vector( 0, BoxHeight / 3, 0 ), 1 ); color( LowerBox, magenta ); color( MiddleBox, yellow ); color( UpperBox, cyan ); color( Cn1, green ); rot_x1 = creparam( cbspline( 3, list( ctlpt( E1, 0 ), ctlpt( E1, -200 ), ctlpt( E1, 200 ), ctlpt( E1, 0 ) ), list( KV_OPEN ) ), 0, 3 ); rot_x2 = creparam( cbspline( 4, list( ctlpt( E1, 0 ), ctlpt( E1, 400 ), ctlpt( E1, -400 ), ctlpt( E1, 0 ) ), list( KV_OPEN ) ), 0, 3 ); rot_y = creparam( cbspline( 2, list( ctlpt( E1, 0 ), ctlpt( E1, 100 ), ctlpt( E1, -100 ), ctlpt( E1, 0 ) ), list( KV_OPEN ) ), 0, 3 ); rot_z = creparam( cbspline( 2, list( ctlpt( E1, 0 ), ctlpt( E1, 1440 ) ), list( KV_OPEN ) ), 0, 3 ); Translate = trans( vector( 0, 0, BoxHeight ) ); attrib( Cn1, "animation", list( rot_z, Translate ) ); Upr = list( Cn1, UpperBox ); attrib( Upr, "animation", list( rot_y, Translate ) ); Mid = list( Upr, MiddleBox ); attrib( Mid, "animation", list( rot_x2, Translate ) ); rbt_hand = list( Mid, LowerBox ); attrib( rbt_hand, "animation", list( rot_x1 ) ); view( rbt_hand, 1 ); In this example, we create four objects, three cubes and one cone, simulating a robotic hand with three edges an a gripper (the cone). The animation is define hierarchically, making it very easy to model the robot.