Home > Resources > Making Animation with Scilab > 9. Animation of a moving block - Preparation
Making Animation with Scilab

9. Animation of a moving block - Preparation

The basic idea of animation of a rigid body motion is the same as that of animation of a moving point discussed in Section 2 and 3. The only difference is that in the case of a rigid body motion the object to draw and erase is a three-dimensional shape.

Let us make an animation of a moving block as an example. This can be done based on the script developed in Section 6 for drawing a block shape in a general configuration.

First, in order to make the script concise let us define a function that returns patches data needed to draw a block shape by plot3d as in Code 1.

calcBlock.sci
function patches = calcBlock(r, R, Lx, Ly, Lz)
// Return patches data of a block geometry

// Vertices
vertices_0 = [
    0,   0,  0;  // #1
    Lx,  0,  0;  // #2
    0,  Ly,  0;  // #3
    0,   0, Lz;  // #4
    Lx, Ly,  0;  // #5
    0,  Ly, Lz;  // #6
    Lx,  0, Lz;  // #7
    Lx, Ly, Lz]; // #8

vertices = transver(vertices_0, r, R);

// Faces
faces = [
    1, 2, 5, 3;  // #1
    1, 3, 6, 4;  // #2
    1, 4, 7, 2;  // #3
    4, 7, 8, 6;  // #4
    2, 5, 8, 7;  // #5
    3, 6, 8, 5]; // #6

// Patches
patches = genpat(vertices, faces);

endfunction
Code 1: Scilab function that returns patches data of a block shape

Using the calcBlock() function in Code 1, we can rewrite the script developed in Section 6 for drawing a block shape in a general configuration concisely as in Code 2 below.

make_block.sce
// make_block.sce

clear; xdel(winsid());

exec('eulerXYZ.sci', -1);
exec('transver.sci', -1);
exec('genpat.sci', -1);
exec('calcBlock.sci', -1);

// Reference position
r = [1; 1; 1];

// Reference orientation
R = eulerXYZ(-%pi/3, 0, %pi/6);

// Side lengths
Lx = 0.15;
Ly = 0.05;
Lz = 0.30;

// Patches
patches = calcBlock(r, R, Lx, Ly, Lz);

// Draw patches
h_fig = figure;
h_fig.background = 8;
h_pat = plot3d(patches.x, patches.y, patches.z);
h_pat.color_mode = 4;
h_pat.foreground = 1;
h_pat.hiddencolor = 4;

// Axes settings
xlabel("x"); ylabel("y"); zlabel("z");
h_axes = gca();
h_axes.isoview = "on";
h_axes.box = "off";
h_axes.rotation_angles = [63.5, -127];
h_axes.data_bounds = [0.8, 0.9, 0.8; 1.3, 1.4, 1.3];
xgrid;
Code 2: Scilab script to draw a block shape