Ytukyg

Working on a little project to do with computer graphics. So far I have (I think) everything in order as the code below patches my world to the screen fine.

However, I have a final hurdle to jump: I would like the code to patch for different values of theta. In the code, it is set at 2*pi/4 but I would like to iterate and patch for every angle between 0:pi/4:2*pi. However, when I try to put the code in a for or while loop it doesn't seem to do what I expect, that is, to patch with one angle, then patch with another etc.

Really stuck I have tried a lot of stuff and now I'm just without any ideas. Would really appreciate any help or suggestions.

function world()

% Defining House Vertices 



house_verts = [-5, 0, -5;

    5, 0, -5;

    5, 10, -5;

    0,15,-5;

    -5,10,-5;

    -5,0,5;

    5,0,5;

    5,10,5;

    0,15,5;

    -5,10,5];        



% Sorting out the homeogenous co-ordinates

ones = [1,1,1,1,1,1,1,1,1,1];

ones=transpose(ones);

house_verts = [house_verts, ones];

house_verts = transpose(house_verts);



% House faces

house_faces = [1,2,3,4,5;

    2,7,8,3,3;

    6,7,8,9,10;

    1,6,10,5,5;

    3,4,9,8,8;

    4,5,10,9,9;

    1,2,7,6,6];



world_pos = ;



% creating a street

street_vector = [1,0,1]; % the direction of the street

orthog_street_vector = [-1,0,1];



for i = 1:15

   % current_pos1 and 2 will be the positions of the two houses

   % opposite each other on the street

   current_pos1 = 30*i*street_vector + 50*orthog_street_vector;

   current_pos2 = 30*i*street_vector - 50*orthog_street_vector;

   world_pos = [world_pos;current_pos1;current_pos2];

end



% initialising world vertices and faces

world_verts = ;

world_faces = ;



% Populating the street

for i =1:size(world_pos,1)

    T = transmatrix(world_pos(i,:)); % a translation matrix

    s = [1,1/2 + rand(),1];

    S=scalmatrix(s); % a matrix for a random scaling of the height (y-coordinate)

    Ry = rotymatrix(rand()*2*pi); % a matrix for a random rotation about the y-axis

    A = T*Ry*S; % the compound transformation matrix to take the house into the world

    obj_faces = size(world_verts,2) + house_faces; %increments the basic house faces to match the current object

    obj_verts = A*house_verts;



    world_verts = [world_verts, obj_verts]; % adds the vertices to the world

    world_faces = [world_faces; obj_faces]; % adds the faces to the world

end



% initialising aligned vertices

align_verts = ;



% Aligning the vertices to the particular camera at angle theta

for elm = world_verts

    x = 350 + 350*cos(2*pi/4);

    z = 350 + 350*sin(2*pi/4);

    y = 80;



    u = [x,y,z];

    v = [250,0,250];





    d = v - u;

    phiy = atan2(d(1),d(3));

    phix = -atan2(d(2),sqrt(d(1)^2+d(3)^2));



    T = transmatrix([-u(1),-u(2),-u(3)]);

    Ry = rotymatrix(phiy);

    Rx = rotxmatrix(phix);  

    A = Rx*Ry*T; 

    align_verts = [align_verts, A*elm];

end





% initialising projected vertices 

proj_verts=;



% Performing the projection

for elm = align_verts

    proj = projmatrix(10);

    projverts = proj*elm;

    projverts = ((10/projverts(3))*projverts);

    proj_verts = [proj_verts,projverts]; 

end



% Displaying the world

for i = 1:size(world_faces,1)

    for j = 1:size(world_faces,2)

        x(j) =proj_verts(1,world_faces(i,j));

        z(j) = proj_verts(2,world_faces(i,j));

    end

    patch(x,z,'w')

end

end







function T = transmatrix(p)

T = [1 0 0 p(1) ; 0 1 0 p(2) ; 0 0 1 p(3) ; 0 0 0 1];

end



function S = scalmatrix(s)

S = [s(1) 0 0 0 ; 0 s(2) 0 0 ; 0 0 s(3) 0 ; 0 0 0 1];

end



function Ry = rotymatrix(theta)

Ry = [cos(theta), 0, -sin(theta),0;

    0,1,0,0;

    sin(theta),0,cos(theta),0;

    0,0,0,1];

end



function Rx = rotxmatrix(phi)

Rx = [1,     0,          0,     0;

      0,  cos(phi),  -sin(phi), 0;

      0,  sin(phi),   cos(phi), 0;

      0,     0,          0,     1];

end



function P = projmatrix(f)

P = [1,0,0,0

     0,1,0,0

     0,0,1,0

     0,0,1/f,0];

end

Updated code: managed to get the loop to work but now there is some bug i don't understand when it does a full rotation again any help would be great.

function world()

% Defining House Vertices 



house_verts = [-5, 0, -5;

    5, 0, -5;

    5, 10, -5;

    0,15,-5;

    -5,10,-5;

    -5,0,5;

    5,0,5;

    5,10,5;

    0,15,5;

    -5,10,5]; 



% Sorting out the homeogenous co-ordinates

ones = [1,1,1,1,1,1,1,1,1,1];

ones=transpose(ones);

house_verts = [house_verts, ones];

house_verts = transpose(house_verts);



% House faces

house_faces = [1,2,3,4,5;

    2,7,8,3,3;

    6,7,8,9,10;

    1,6,10,5,5;

    3,4,9,8,8;

    4,5,10,9,9;

    1,2,7,6,6];



world_pos = ;



% creating a street

street_vector = [1,0,1]; % the direction of the street

orthog_street_vector = [-1,0,1];



for i = 1:15

   % current_pos1 and 2 will be the positions of the two houses

   % opposite each other on the street

   current_pos1 = 30*i*street_vector + 50*orthog_street_vector;

   current_pos2 = 30*i*street_vector - 50*orthog_street_vector;

   world_pos = [world_pos;current_pos1;current_pos2];

end



% initialising world vertices and faces

world_verts = ;

world_faces = ;



% Populating the street

for i =1:size(world_pos,1)

    T = transmatrix(world_pos(i,:)); % a translation matrix

    s = [1,1/2 + rand(),1];

    S=scalmatrix(s); % a matrix for a random scaling of the height (y-coordinate)

    Ry = rotymatrix(rand()*2*pi); % a matrix for a random rotation about the y-axis

    A = T*Ry*S; % the compound transformation matrix to take the house into the world

    obj_faces = size(world_verts,2) + house_faces; %increments the basic house faces to match the current object

    obj_verts = A*house_verts;



    world_verts = [world_verts, obj_verts]; % adds the vertices to the world

    world_faces = [world_faces; obj_faces]; % adds the faces to the world

end



% initialising aligned vertices

align_verts = ;

% initialising projected vertices 

proj_verts=;

% Aligning the vertices to the particular camera at angle theta

theta = 0;

t = 0;

while t < 100

    proj_verts=;

    align_verts = ;

    for elm = world_verts

        x = 300 + 300*cos(theta);

        z = 300 + 300*sin(theta);

        y = 80;



        u = [x,y,z];

        v = [200,0,200];





        d = v - u;

        phiy = atan2(d(1),d(3));

        phix = -atan2(d(2),sqrt(d(1)^2+d(3)^2));



        T = transmatrix([-u(1),-u(2),-u(3)]);

        Ry = rotymatrix(phiy);

        Rx = rotxmatrix(phix);  

        A = Rx*Ry*T; 

        align_verts = [align_verts, A*elm];

    end



    % Performing the projection

    for elm = align_verts

        proj = projmatrix(6);

        projverts = proj*elm;

        projverts = ((6/projverts(3))*projverts);

        proj_verts = [proj_verts,projverts]; 

    end



    % Displaying the world

    for i = 1:size(world_faces,1)

        for j = 1:size(world_faces,2)

            x(j) = proj_verts(1,world_faces(i,j));

            z(j) = proj_verts(2,world_faces(i,j));

        end

        patch(x,z,'w')

        pbaspect([1,1,1]); % adjusts the aspect ratio of the figure



    end





title('Projected Space', 'fontsize', 16, 'interpreter', 'latex')

xlabel('$x$', 'fontsize', 16, 'interpreter', 'latex')

ylabel('$z$', 'fontsize', 16, 'interpreter', 'latex')

zlabel('$y$', 'fontsize', 16, 'interpreter', 'latex')



axis([-5,5,-5,2,0,5]) % sets the axes limits 

view(0,89)

pause(0.0000001)

theta = theta + 0.01;

clf

end



end







function T = transmatrix(p)

T = [1 0 0 p(1) ; 0 1 0 p(2) ; 0 0 1 p(3) ; 0 0 0 1];

end



function S = scalmatrix(s)

S = [s(1) 0 0 0 ; 0 s(2) 0 0 ; 0 0 s(3) 0 ; 0 0 0 1];

end



function Ry = rotymatrix(theta)

Ry = [cos(theta), 0, -sin(theta),0;

    0,1,0,0;

    sin(theta),0,cos(theta),0;

    0,0,0,1];

end



function Rx = rotxmatrix(phi)

Rx = [1,     0,          0,     0;

      0,  cos(phi),  -sin(phi), 0;

      0,  sin(phi),   cos(phi), 0;

      0,     0,          0,     1];

end



function P = projmatrix(f)

P = [1,0,0,0

     0,1,0,0

     0,0,1,0

     0,0,1/f,0];

end