object3d_persp1.m

用MATLAB做的3D图形的变化,这个是范例,希望会帮到大家

% A simple program to demonstrate perspective projection
% on wire-frame objects.

close all;
clear all;

% make a model; first define the points...
cube.points = [ % a unit cube
  [ 1/2  1/2  1/2 1]; % 1
  [-1/2  1/2  1/2 1]; % 2
  [-1/2 -1/2  1/2 1]; % 3
  [ 1/2 -1/2  1/2 1]; % 4
  [ 1/2  1/2 -1/2 1]; % 5
  [-1/2  1/2 -1/2 1]; % 6
  [-1/2 -1/2 -1/2 1]; % 7
  [ 1/2 -1/2 -1/2 1]; % 8
]';
% now define the edges - using point indices
cube.edges = [
  [1 2]; [2 3]; [3 4]; [4 1];...
  [5 6]; [6 7]; [7 8]; [8 5];...
  [1 5];...
  [2 6];...
  [3 7];...
  [4 8]
];

% Make up a few (4x4) matrix transforms
% translation
t = [1 -2 6]';
T = [
  1 0 0 t(1);
  0 1 0 t(2);
  0 0 1 t(3);
  0 0 0 1;
];

% rotate about y
theta = pi/6;
Ry = [
  cos(theta) 0 sin(theta)  0;
  0              1 0              0;
  -sin(theta) 0 cos(theta) 0;
  0              0 0             1
];

% an overall scale
s = 10;
S = [
  s 0 0 0;
  0 s 0 0;
  0 0 s 0;
  0 0 0 1;
];

% perspective transform
P = [
  1 0 0 0;
  0 1 0 0;
  0 0 1 0;
  0 0 1 0;
];


% transform and project the cube
cube.image = P * S* T * Ry * cube.points;

% convert homogeneous coords to physical coords
cube.image = cube.image ./ repmat( cube.image(4,:), 4, 1 );

% draw the result
figure;
axis equal;
hold on;
%plot( 1/2,1/2,'w');
%plot( -1/2,-1/2,'w');
for i = 1:size(cube.edges,1)
  % get the coordinates of the edge
  p = [cube.image( :, cube.edges(i,1) ), cube.image( :, cube.edges(i,2) ) ];
  % draw the egde
  plot( p(1,:), p(2,:) );
end


% do it again
t = [0 0 5]';
T = [
  1 0 0 t(1);
  0 1 0 t(2);
  0 0 1 t(3);
  0 0 0 1;
];
cube.image = P * T *cube.points;
cube.image = cube.image ./ repmat( cube.image(4,:), 4, 1 );

for i = 1:size(cube.edges,1)
  % get the coordinates of the edge
  p = [cube.image( :, cube.edges(i,1) ), cube.image( :, cube.edges(i,2) ) ];
  % draw the egde
  plot( p(1,:), p(2,:) );
end