The Ring programming language version 1.5.2 book - Part 53 of 181
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This document discusses RingFreeGLUT, a Ring binding library for the FreeGLUT library. It provides examples of creating OpenGL windows and contexts with RingFreeGLUT, drawing basic shapes, handling events like keyboard input and window resizing, and implementing a basic 3D camera. Key concepts covered include initializing GLUT, creating windows, drawing with OpenGL, handling events, and manipulating the camera position and orientation.
The Ring programming language version 1.5.2 book - Part 53 of 181
- 1. Ring Documentation, Release 1.5.2 • OpenGL 4.4 • OpenGL 4.5 • OpenGL 4.6 For example, if you want to use OpenGL 2.1 then load RingOpenGL 2.1 library load "opengl21lib.ring" 54.3 What is RingFreeGLUT? RingFreeGLUT contains the Ring binding to the FreeGLUT library You can learn about FreeGLUT from : http://freeglut.sourceforge.net/ To use the RingFreeGLUT library, Just load the library load "freeglut.ring" 54.4 The First Window using RingFreeGLUT Example: load "freeglut.ring" func main glutInit() glutInitDisplayMode(GLUT_SINGLE) glutInitWindowSize(800, 600) glutInitWindowPosition(100, 10) glutCreateWindow("RingFreeGLUT - Test 1") glutDisplayFunc(:displayCode) glutMainLoop() func displaycode Screen Shot 54.3. What is RingFreeGLUT? 495
- 2. Ring Documentation, Release 1.5.2 54.5 Drawing using RingOpenGL Example: load "freeglut.ring" load "opengl21lib.ring" func main glutInit() glutInitDisplayMode(GLUT_SINGLE) glutInitWindowSize(800, 600) glutInitWindowPosition(100, 10) glutCreateWindow("RingFreeGLUT - Test 2") glutDisplayFunc(:displayCode) glutMainLoop() func displaycode glClear(GL_COLOR_BUFFER_BIT) glColor3f(0,255,0) glBegin(GL_POLYGON) glVertex3f(0.0, 0.0, 0.0) 54.5. Drawing using RingOpenGL 496
- 3. Ring Documentation, Release 1.5.2 glVertex3f(0.5, 0.0, 0.0) glVertex3f(0.5, 0.5, 0.0) glVertex3f(0.0, 0.5, 0.0) glEnd() glColor3f(255,0,0) glBegin(GL_POLYGON) glVertex3f(0.0, 0.0, 0.0) glVertex3f(0.5, 0.0, 0.0) glVertex3f(-0.5,- 1, 0.0) glVertex3f(0.0, -1, 0.0) glEnd() glColor3f(0,0,255) glBegin(GL_POLYGON) glVertex3f(0.0, 0.0, 0.0) glVertex3f(-0.5, 0.0, 0.0) glVertex3f(-0.5,- 0.5, 0.0) glVertex3f(0.0, -0.5, 0.0) glEnd() glFlush() Screen Shot 54.5. Drawing using RingOpenGL 497
- 4. Ring Documentation, Release 1.5.2 54.6 The First Triangle Example: load "freeglut.ring" load "opengl21lib.ring" func main glutInit() glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA) glutInitWindowSize(320,320) glutInitWindowPosition(100, 10) glutCreateWindow("RingFreeGLUT - Test 3") glutDisplayFunc(:renderScene) glutMainLoop() func renderScene glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) glBegin(GL_TRIANGLES) glVertex3f(-0.5,-0.5,0.0) glVertex3f(0.5,0.0,0.0) glVertex3f(0.0,0.5,0.0) glEnd() glutSwapBuffers() Screen Shot 54.6. The First Triangle 498
- 5. Ring Documentation, Release 1.5.2 54.7 Window Resize Event Example: load "freeglut.ring" load "opengl21lib.ring" func main // init GLUT and create window glutInit() glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA) glutInitWindowPosition(100,100) glutInitWindowSize(320,320) glutCreateWindow("RingFreeGLUT - Test 4") glutDisplayFunc(:renderScene) glutReshapeFunc(:changeSize) glutMainLoop() func renderScene glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) glBegin(GL_TRIANGLES) glVertex3f(-2,-2,-5.0) glVertex3f(2,0.0,-5.0) glVertex3f(0.0,2,-5.0) glEnd() glutSwapBuffers() func changesize h = glutEventHeight() w = glutEventWidth() // Prevent a divide by zero, when window is too short // (you cant make a window of zero width). if (h = 0) h = 1 ok ratio = w * 1.0 / h // Use the Projection Matrix glMatrixMode(GL_PROJECTION) // Reset Matrix glLoadIdentity() // Set the viewport to be the entire window glViewport(0, 0, w, h) // Set the correct perspective. gluPerspective(45,ratio,1,100) 54.7. Window Resize Event 499
- 6. Ring Documentation, Release 1.5.2 // Get Back to the Modelview glMatrixMode(GL_MODELVIEW) 54.8 Triangle Rotation Example: load "freeglut.ring" load "opengl21lib.ring" angle = 0 func main // init GLUT and create window glutInit() glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA) glutInitWindowPosition(100,100) glutInitWindowSize(320,320) glutCreateWindow("RingFreeGLUT - Test 5") glutDisplayFunc(:renderScene) glutReshapeFunc(:changeSize) glutIdleFunc(:renderScene) glutMainLoop() func renderScene // Clear Color and Depth Buffers glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) // Reset transformations glLoadIdentity() // Set the camera gluLookAt( 0.0, 0.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0) glRotatef(angle, 0.0, 1.0, 0.0) glBegin(GL_TRIANGLES) glVertex3f(-2.0,-2.0, 0.0) glVertex3f( 2.0, 0.0, 0.0) glVertex3f( 0.0, 2.0, 0.0) glEnd() angle+=0.1 glutSwapBuffers(); func changesize h = glutEventHeight() w = glutEventWidth() 54.8. Triangle Rotation 500
- 7. Ring Documentation, Release 1.5.2 // Prevent a divide by zero, when window is too short // (you cant make a window of zero width). if (h = 0) h = 1 ok ratio = w * 1.0 / h // Use the Projection Matrix glMatrixMode(GL_PROJECTION) // Reset Matrix glLoadIdentity() // Set the viewport to be the entire window glViewport(0, 0, w, h) // Set the correct perspective. gluPerspective(45,ratio,1,100) // Get Back to the Modelview glMatrixMode(GL_MODELVIEW) Screen Shot 54.9 Keyboard Events and Colors Example: load "freeglut.ring" load "opengl21lib.ring" 54.9. Keyboard Events and Colors 501
- 8. Ring Documentation, Release 1.5.2 angle = 0 red=1.0 blue=1.0 green=1.0 func main // init GLUT and create window glutInit() glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA) glutInitWindowPosition(100,100) glutInitWindowSize(320,320) glutCreateWindow("RingFreeGLUT - Test 6") glutDisplayFunc(:renderScene) glutReshapeFunc(:changeSize) glutIdleFunc(:renderScene) // here are the new entries glutKeyboardFunc(:processNormalKeys) glutSpecialFunc(:processSpecialKeys) glutMainLoop() func renderScene // Clear Color and Depth Buffers glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) // Reset transformations glLoadIdentity() // Set the camera gluLookAt( 0.0, 0.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0) glRotatef(angle, 0.0, 1.0, 0.0) glColor3f(red,green,blue); glBegin(GL_TRIANGLES) glVertex3f(-2.0,-2.0, 0.0) glVertex3f( 2.0, 0.0, 0.0) glVertex3f( 0.0, 2.0, 0.0) glEnd() angle+=0.1 glutSwapBuffers(); func changesize h = glutEventHeight() w = glutEventWidth() // Prevent a divide by zero, when window is too short 54.9. Keyboard Events and Colors 502
- 9. Ring Documentation, Release 1.5.2 // (you cant make a window of zero width). if (h = 0) h = 1 ok ratio = w * 1.0 / h // Use the Projection Matrix glMatrixMode(GL_PROJECTION) // Reset Matrix glLoadIdentity() // Set the viewport to be the entire window glViewport(0, 0, w, h) // Set the correct perspective. gluPerspective(45,ratio,1,100) // Get Back to the Modelview glMatrixMode(GL_MODELVIEW) func processNormalKeys key = GLUTEventKey() if key = 27 shutdown() ok func processSpecialKeys key = GLUTEventKey() switch key on GLUT_KEY_F1 red = 1.0 green = 0.0 blue = 0.0 on GLUT_KEY_F2 red = 0.0 green = 1.0 blue = 0.0 on GLUT_KEY_F3 red = 0.0 green = 0.0 blue = 1.0 off Screen Shot 54.9. Keyboard Events and Colors 503
- 10. Ring Documentation, Release 1.5.2 54.10 The Camera Example: load "freeglut.ring" load "opengl21lib.ring" // angle of rotation for the camera direction angle=0.0 // actual vector representing the camera's direction lx=0.0 lz=-1.0 // XZ position of the camera x=0.0 z=5.0 func drawSnowMan glColor3f(1.0, 1.0, 1.0) // Draw Body glTranslatef(0.0 ,0.75, 0.0) glutSolidSphere(0.75,20,20) // Draw Head glTranslatef(0.0, 1.0, 0.0) glutSolidSphere(0.25,20,20) // Draw Eyes glPushMatrix() glColor3f(0.0,0.0,0.0) glTranslatef(0.05, 0.10, 0.18) 54.10. The Camera 504