1. Computer Graphics -practical- Lecture 6

2. (visual c++) open gl library To use open GL with VC++ we add these files:- 1)Glut.h C:\program files\ Microsoft visual studio\vc98\include\GL 2)Glut32.dll C:\windows\system 3)Glut32.lib C:\program files\ Microsoft visual studio\ v098\lib After include these files start the visual C++ program.

3. Getting Started You’ll be using VC++ 2010 environment (Download)Download You should already have OpenGL libraries: glut32.dll glut32.lib glut.h GLUT files from the web (www.xmission.com/~nate/glut.html)www.xmission.com/~nate/glut.html

4. To draw the main shape (line, triangle, dot ……)the screen is divided to :

5. In open GL we need three functions to draw the main shapes : (program steps ) Open GL program structure: Header files Function to determine the type of the shape Function to determine the points of the shape Function to end of the points of the shape

6. Function that use to determine the type of the shapes: glBegin(NAME); NameDESCREPTION GL_POINTSDraw point GL_LINES Draw line GL_TRIANGLES To Draw triangle0lo GL_POLYGON To Draw polygon

8. Function that use to determine the points of the shapes:- two dimensional or 3 dimensional glVertex2F(X.Y); glVertex3F(X.Y); *Function to end the points of the shape glEnd();

9. #include

10. Write the VC++ program using open GL library to draw point. Open the VC++ to write the code Start --- visual C++2010 ----new Project :win 32 application Files: C++ source code Then write the program name Name: dpoint

11. #include void display() { glClear(GL_COLOR_BUFFER_BIT); glPointSize(8); glBegin(GL_POINTS); glVertex2f(0.0,0.0); glEnd(); glFlush(); }

12. int main(int argc, char **argv) { glutInit(&argc,argv); glutCreateWindow("draw point"); glutDisplayFunc(display); glutMainLoop(); return 0; }

13. #include #include //header file, define the opengl library void display() //Function to display { glClear(GL_COLOR_BUFFER_BIT); /* this function use to clear the buffer before draw any shape */ glPointSize(8); glBegin(GL_POINTS); /* function to declare the type of the shape “here to draw point” */ glVertex2f(0.0,0.0); /* function to determine the place of the shape on the screen */ glEnd(); /*used to determine the end of the shape point */ glFlush(); //function to view the shape }

14. // For user interface int main(int argc, char **argv) { glutInit(&argc,argv); /* Open gl utility toolkit: use to call glut function to view window */ glutCreateWindow("draw point"); /* name of the window (any name) */ glutDisplayFunc(display); /* call the function display */ glutMainLoop(); /* function for looping the program, then all ways come at the end (Display the window until you close) */ return 0; }