The Ring programming language version 1.5.4 book - Part 54 of 185
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The document describes code for rendering 3D graphics using OpenGL in Ring. It includes examples of drawing simple shapes like triangles and polygons, handling window resizing, adding keyboard input for rotation and color changes, and implementing a 3D camera that can be moved around the scene using keys. The examples demonstrate basic 3D rendering techniques and interfacing with the GLUT library for window and event handling in Ring.
The Ring programming language version 1.5.4 book - Part 54 of 185
- 1. Ring Documentation, Release 1.5.4 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 505
- 2. Ring Documentation, Release 1.5.4 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 506
- 3. Ring Documentation, Release 1.5.4 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 507
- 4. Ring Documentation, Release 1.5.4 // 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 508
- 5. Ring Documentation, Release 1.5.4 // 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 509
- 6. Ring Documentation, Release 1.5.4 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 510
- 7. Ring Documentation, Release 1.5.4 // (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 511
- 8. Ring Documentation, Release 1.5.4 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 512
- 9. Ring Documentation, Release 1.5.4 glutSolidSphere(0.05,10,10) glTranslatef(-0.1, 0.0, 0.0) glutSolidSphere(0.05,10,10) glPopMatrix() // Draw Nose glColor3f(1.0, 0.5 , 0.5) glutSolidCone(0.08,0.5,10,2) func changeSize w = glutEventWidth() h = glutEventHeight() // 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(45.0, ratio, 0.1, 100.0); // Get Back to the Modelview glMatrixMode(GL_MODELVIEW) func processNormalKeys key = glutEventKey() if key = 27 shutdown() ok func renderScene // Clear Color and Depth Buffers glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) // Reset transformations glLoadIdentity() // Set the camera 54.10. The Camera 513
- 10. Ring Documentation, Release 1.5.4 gluLookAt( x, 1.0, z, x+lx, 1.0, z+lz, 0.0, 1.0, 0.0) // Draw ground glColor3f(0.9, 0.9, 0.9) glBegin(GL_QUADS) glVertex3f(-100.0, 0.0, -100.0) glVertex3f(-100.0, 0.0, 100.0) glVertex3f( 100.0, 0.0, 100.0) glVertex3f( 100.0, 0.0, -100.0) glEnd() // Draw 36 SnowMen for i = -3 to 2 for j=-3 to 2 glPushMatrix() glTranslatef(i*10.0,0,j * 10.0) drawSnowMan() glPopMatrix() next next glutSwapBuffers() func processSpecialKeys key = glutEventKey() fraction = 0.1 switch key on GLUT_KEY_LEFT angle -= 0.01 lx = sin(angle) lz = -cos(angle) on GLUT_KEY_RIGHT angle += 0.01 lx = sin(angle) lz = -cos(angle) on GLUT_KEY_UP x += lx * fraction z += lz * fraction on GLUT_KEY_DOWN x -= lx * fraction z -= lz * fraction off func main // init GLUT and create window glutInit() glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA) 54.10. The Camera 514