3D Tree Generator. 3D Fractal Tree Generator. Konstantinos Seventekidis DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF IOANNINA

Transcription

1 3D Tree Generator 3D Fractal Tree Generator Konstantinos Seventekidis Graphical Grammars DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF IOANNINA

2 Contents: 1. Introduction to the problem 2. How to install 3. How to run the demo 3.1 Installing under Windows distribution 3.2 Installing under Linux/UNIX distribution 4. Create an input file 4.1 Settings for the plant 4.2 Primitives of the plant 4.3 The grammar 5. Keyboard commands 6. Components of the tree 7. Tree photographs gallery

3 1. Introduction to the problem With the term graphical grammar we mean all the grammars we use in our every day life. This grammar has sentences, rules and words and we use them to represent something that exists. Here we will use them to represent a 3D tree. Because in the nature some information repeats with the same pattern, we use fractals. A definition of a fractal is: Fractal is any repeating pattern. Our nature is full of fractals and because of the tendency, we define a recursive grammar that can easily create plants and in particular trees in our case trees. With a fractal we can represent anything that exists in the nature, as long as we have find the appropriate grammar. Specifically, the grammar is constructed from a set of rules (the grammar) and the words (sentences primitives). In our plant sentence, the words are plant primitives and define in a singular plant part, like a flower or a branch, and the grammar or the order of the words defines the shape of the tree. The grammar is then expanded recursively so that the same pattern will be repeated. 2. How to install First of all, this application runs under the platform of UNIX, Linux e.t.c and under any platform of Windows. For windows, its is necessary to do the followings: To build the glut dll: First, open Microsoft Developer Studio. Then, select File -> Open Workspace and find the glut.dsw file in the file dialog and double-click on it. Finally, select Build -> Build glut32.dll. When the build is finished, it will copy: glut32.dll to %WinDir%\System, glut32.lib to $(MSDevDir)\..\..\VC98\lib, and glut.h to $(MSDevDir)\..\..\VC98\include\GL. Additional workspace files have been included in the progs, test and lib directories to build the progs, tests and libs respectively.

4 3. How to run the demo 3.1 Installing under Windows distribution After you do this, you open the Microsoft Visual C++ workspace and you do some settings: You open the source code choosing File Open like this: We must note here that you can place the source code anywhere you want in your computer. As you can see from the picture next to this, you can also open the source code by pressing the combination of ctrl + O letter from the keyboard. Or you choose open Workspace if you are not running the application for first time. By doing this you have opened a workspace, then you need to add file in the workspace. This is done by following the steps shown in the second picture.

5 After all this, provided that you have opened the source code you choose from the menu Project Settings or you can press from the keyboard the keys Alt + F7 as shown in the following picture: After the next form will open:

6 We choose fourth label with the name Link : And we add at the begging of text box with the name Object/library modules: the following: OpenGL32.lib GLu32.lib GLaux.lib GLut32.lib So now we have the following picture:

7 We have to compile the project now, so we choose Build Compile Filename.cpp as it follows: As long as no error found during compilation, you will see the following: You have to see build the execute file, by choosing: Build Build Filename.exe. If everything are correct you will receive the following: Then, to execute the exe file you must press Ctrl + F5 or to choose Build!Execute Filename.exe. The opengl window will appear if everything are correct.

8 3.2 Installing under Linux/UNIX distribution The procedure for installing or compiling the project under Linux is much more simple. The only necessary library is Mesa3D, which is on the package of all the Linux distributions. You will need the next files: Makefile: necessary for the compilation of the project Source code which includes: o trees.c o io.h o defines.h o Makefile o and of the input files and all this can be found under: CDROM:\SourceCode\Linux\* The project runs under UNIX also, with the appropriate makefile, which is found at the directory: CDROM:\SourceCode\UNIX\Makefile 4. Create an input file 4.1 Settings for the plant At the begging of the file the user can arrange some parameters, like the angle between the stem and a branch of the tree, the angle between the x-z axis to rotate the tree and to represent at 3 dimensions and the color of the background. Below we give more details about this at the next. a) Angle1: is the angle between a stem and a branch. It is defined in degrees and it can take a negative value. This value shows that the plant will rotate as indices of a clock and if the value is positive it will rotate reversely from the indices of the clock. Syntax: angle1 degrees b) Angle2: is the angle between the x-z axis and is used to make rotations and to represent the plant in 3 dimensions. Syntax: angle2 degrees.

9 c) Bgcolor: defines the color of the background color of the main window. We use three parameters for this option. All the parameters take values from 0.0 to 1.0. The first parameter shows how we use the red color, the second the green color and the third the blue. As bigger is the values, so more the color is used. (We use the RGB system for color). An example of begging of the input file looks like this: angle angle2 15 bgcolor The default values of these parameters are: Angle1=20 0 Angle2 = 10 0 Bgcolor = Black (red = 0.0, green = 0.0 and blue = 0.0) 4.2 Primitives of the plant The plant is represented by three parts, which are the followings: Part of the plant Stem Branch Description The user can directly specify which plant primitive corresponds to which identifier by explicitly defining the relationship at the end of the input file. For example, if the user wanted to define the identifier F to represent a stem primitive, the user would type the following at the end of the input file: stem F The user specifies what is branch according the grammar. For example, if the user want to define that the identifier B is branch, he must denote as follows: branch B Leaf The user specifies what is leaf according the grammar. For example, if the user want to define that the identifier L is leaf, he must denote as follows: leaf L

10 4.3 The grammar We use the grammar to define the plant structure. This is a method of defining a plant structure using recursive definitions for plant primitives using a grammar. Plants are drawn according to the current grammar, and this grammar is expanded using the definitions each time the spacebar key is pressed. This grammar and definitions makes up the remainder of the input file. The first line is a list of primitives to draw. Typically, we start out with one primitive, for example F. The following lines are definitions for the plant primitives. For example, we could define: F -> FFQ Q -> QQ P -> F This would mean that the first time that the program will run, it would receive the command to draw primitive F. It would define an F to be FFQ, and it would draw two F and a Q. Expanding the grammar with spacebar would result in FFQ being expanded to be FFQFFQQQ. Another expansion would yield FFQFFQQQFFQFFQQQQQQQ according to the first and the second rule. Some special symbols that we use in the definitions are: Symbol Action + Rotate according to the indices of the clock for the specified amount - Rotate reversely to the indices of the clock for the specified amount ] Push the current position and rotation onto the stack [ Pop the current position and rotation onto the stack < Scale down the current size of primitives by the specified percentage > Scale up the current size of primitives by the specified percentage An example that shows all the operations descript above is the following: angle angle2 15 scale 10 bgcolor F F->XF X->[+F]F[-F]P P->F stem F branch X leaf P

11 5. Keyboard commands The keys we use to manage the camera are the followings: Key F3 F4 Operation It moves the camera down It moves the camera right It moves the camera left It moves the camera up It rotates the camera right around the plant It rotates the camera left around the plant The keys we use to manage the window are the followings: Key Esc or q 'F or f Mouse Operation To terminate the program and to close the window For full screen or to return to the normal size which is 640x480 To move the window when is not on full screen state The keys we use to manage the plant are the followings: Key Operation = Zoom in towards the plant Zoom out

12 6. Components of the tree The tree generator uses three plant primitives as shown at the next pictures, with descriptions and specifications. Name: stem Description: long, thin, green, stick Specifications: moves current position to the end of the stem Picture: Name: branch Description: short, wide Specifications: moves current position to the end of branch Picture: Name: leaf Description: green diamond, rotated to the side Specifications: does not move current position Picture:

13 7. Tree photo gallery Here, you can see some images by the demo of the input files: Figure 1

14 Figure 2

15 Figure 3

16 Figure 4 (Default angle between stem and branches, angle (x-z axis) and background color)

17 Figure 5

18 Figure 6 With the red color: stems With the blue color: branches With the green color: leafs