Tze-Yeung Lau

Final Project Report:
 
       Project Description:
                Visualization of grass on the floor, and the reaction of the grass applying wind on it.
                I am creating grasses that will be generated in group.  A group of grasses general have an average of
             5-6 pieces of grass. and grass within a group will be generated around the center grass of the grass group.
                Grasses are possible to have the same x,y values (I used XY plane as my plane and grass grow on Z axis.
                Wind is implemented with directional vectors and moving particles.  The directional vector will cause the
             moves of particles.  When particle "hit" the grass, the grass will bend according to the force given by the
             wind particles.
 
           Detail:
                  Map:
                        Map is a flat ground if there is no modifications made by the user.  There is nine control points on the
                       ground no matter how large it is.  (It is too slow to find the normals of polygons and vertex when the
                       map is larger)  Normals of the control vertex, and normal of its corresponding polygons are calculated
                       for a more smooth surface.
                         Ground is make of 8 triangles.
 
                             

                             
 
                    Grass:
                        Each grass consists of 14 cylinders with a cone at the tip of it.  Each joint of a grass have different angle,
                       and they  change differently according to how much force is apply to it.  When the angle (angle with normal)
                        is larger, the wind will have lesser effect to the grass.  I implemented the grass this way because I don't
                        want the grass to bend like a straight line.

                      Wind:
                            Wind particles are data that contain it v vector, the vector changes depends on where it locate, RK4
                          Interpolation is used to update the wind particles.
                             Vectors that updates the wind particles are three dimentional vectors.  Tornado like wind could be
                          implemented.  I have a tornado data set, but It didn't come out as I thought.

                     Progress:
                            I visualized grass and its animation and I thought.  (I don't know if it is truely natural movement, but I think
                         It is real enough)
 
                             I begin this project with only one piece of grass with only one strip, after that, I give more strip to it.
                          When the piece of grass is ready to be blow by wind, I used the two dimension wind as the one in program 3.
                          It didn't work as I thought It would at first, and all grasses disappear somehow due to the wrong calculation
                          of the grass angles.  The next steps I did was to make everything 3D.
                             I modified all the 2D wind in to 3D wind, in this process, I used Trilinear Interpolation to calculation the affects
                          to the wind particle from the vectors surrounds it.  Since Z vector is in the wind vector now, I added the z affects
                          to the grass.  Z vector won't change the Z angle of the grass (I didn't change it at all, but it is there though), instead
                          it changes both X and Y angles of the grass.
                              After all these ideas are done, I started working on the height of the ground, I used 9 control points and join
                          them together with 8 triangles, and normals for each vertices and polygons are calculated to make the surface
                          smoother.  Since I grow my grasses on a flat land at first, I have to use Bilinear Interpolation to find the translate in
                          Z of the each grass.

                     Fog:
                            The last steps that I do for this project is Fog, which is my original project proposal.  I didn't use particles
                           to make though it was my original idea.  It is pretty impossible to have particles cove the whole ground and
                           use GLBlend to make it transparent.  (It will be too slow)  As a result, I used GLFog.
 
                              

                     There are some unexpected effect after implementing the fog, so I add some extra features, like changing
                    color of the fog.  It looks like we are under the sea....
 
                               

             Future:
                    I would really like to do the grey scale terrain mapping technique.  This technique create terrain with a
                 grey-scale bit map.  The whiter the bit map is, the higher the terrain.  I didn't allow the user to design their
                 own wind, and it will probably be implemented in the future when I have more time working on this project.