The Ring programming language version 1.6 book - Part 57 of 189
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This document provides code for rendering a 3D scene with OpenGL using GLUT (OpenGL Utility Toolkit) in Ring. It defines functions for drawing a snowman, handling window resizing, rendering the scene, processing keyboard input, and the main function that initializes GLUT and enters the event loop. Mouse handling functions are also defined to allow rotating the camera view with mouse movement and clicks. The code renders a ground plane with multiple snowmen placed in a grid that can be navigated around using keyboard controls or mouse input.
The Ring programming language version 1.6 book - Part 57 of 189
- 1. Ring Documentation, Release 1.6 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 55.10. The Camera 533
- 2. Ring Documentation, Release 1.6 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) 55.10. The Camera 534
- 3. Ring Documentation, Release 1.6 glutInitWindowPosition(100,100) glutInitWindowSize(320,320) glutCreateWindow("RingFreeGLUT - Test 7") // register callbacks glutDisplayFunc(:renderScene) glutReshapeFunc(:changeSize) glutIdleFunc(:renderScene) glutKeyboardFunc(:processNormalKeys) glutSpecialFunc(:processSpecialKeys) // OpenGL init glEnable(GL_DEPTH_TEST) // enter GLUT event processing cycle glutMainLoop() Screen Shot Another 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 // the key states. These variables will be zero //when no key is being presses deltaAngle = 0.0 55.10. The Camera 535
- 4. Ring Documentation, Release 1.6 deltaMove = 0 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 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) 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) glRotatef(0.0,1.0, 0.0, 0.0) glutSolidCone(0.08,0.5,10,2) 55.10. The Camera 536
- 5. Ring Documentation, Release 1.6 func computePos deltaMove x += deltaMove * lx * 0.1 z += deltaMove * lz * 0.1 func computeDir deltaAngle angle += deltaAngle lx = sin(angle) lz = -cos(angle) func renderScene if deltaMove computePos(deltaMove) ok if deltaAngle computeDir(deltaAngle) ok // Clear Color and Depth Buffers glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) // Reset transformations glLoadIdentity() // Set the camera 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 pressKey key = glutEventKey() xx = glutEventX() 55.10. The Camera 537
- 6. Ring Documentation, Release 1.6 yy = glutEventY() switch key on GLUT_KEY_LEFT deltaAngle = -0.01 on GLUT_KEY_RIGHT deltaAngle = 0.01 on GLUT_KEY_UP deltaMove = 0.5 on GLUT_KEY_DOWN deltaMove = -0.5 off func releaseKey key = glutEventKey() switch key on GLUT_KEY_LEFT deltaAngle = 0.0 on GLUT_KEY_RIGHT deltaAngle = 0.0 on GLUT_KEY_UP deltaMove = 0 on GLUT_KEY_DOWN deltaMove = 0 off func main // init GLUT and create window glutInit() glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA) glutInitWindowPosition(100,100) glutInitWindowSize(320,320) glutCreateWindow("RingFreeGLUT - Test 8") // register callbacks glutDisplayFunc(:renderScene) glutReshapeFunc(:changeSize) glutIdleFunc(:renderScene) glutSpecialFunc(:pressKey) // here are the new entries glutIgnoreKeyRepeat(1) glutSpecialUpFunc(:releaseKey) // OpenGL init glEnable(GL_DEPTH_TEST) // enter GLUT event processing cycle glutMainLoop() 55.10. The Camera 538
- 7. Ring Documentation, Release 1.6 55.11 Mouse Events 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 // the key states. These variables will be zero //when no key is being presses deltaAngle = 0.0 deltaMove = 0.0 xOrigin = -1 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 drawSnowMan glColor3f(1.0, 1.0, 1.0) // Draw Body glTranslatef(0.0 ,0.75, 0.0) glutSolidSphere(0.75,20,20) 55.11. Mouse Events 539
- 8. Ring Documentation, Release 1.6 // 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) 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) glRotatef(0.0,1.0, 0.0, 0.0) glutSolidCone(0.08,0.5,10,2) func computePos deltaMove x += deltaMove * lx * 0.1 z += deltaMove * lz * 0.1 func renderScene if deltaMove computePos(deltaMove) ok // Clear Color and Depth Buffers glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) // Reset transformations glLoadIdentity() // Set the camera 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() 55.11. Mouse Events 540
- 9. Ring Documentation, Release 1.6 next next glutSwapBuffers() func processNormalKeys key = glutEventKey() if key = 27 shutdown() ok func pressKey key = glutEventKey() switch key on GLUT_KEY_UP deltaMove = 0.5 on GLUT_KEY_DOWN deltaMove = -0.5 off func releaseKey key = glutEventKey() switch key on GLUT_KEY_UP deltaMove = 0 on GLUT_KEY_DOWN deltaMove = 0 off func mouseMove xx = glutEventX() yy = glutEventY() // this will only be true when the left button is down if xOrigin >= 0 // update deltaAngle deltaAngle = (xx - xOrigin) * 0.001 // update camera's direction lx = sin(angle + deltaAngle) lz = -cos(angle + deltaAngle) ok func mouseButton button = glutEventButton() state = glutEventState() xx = glutEventX() yy = glutEventY() // only start motion if the left button is pressed 55.11. Mouse Events 541
- 10. Ring Documentation, Release 1.6 if button = GLUT_LEFT_BUTTON // when the button is released if state = GLUT_UP angle += deltaAngle xOrigin = -1 else // state = GLUT_DOWN xOrigin = xx ok fflush(stdout) ok func main // init GLUT and create window glutInit() glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA) glutInitWindowPosition(100,100) glutInitWindowSize(320,320) glutCreateWindow("RingFreeGLUT - Test 9") // register callbacks glutDisplayFunc(:renderScene) glutReshapeFunc(:changeSize) glutIdleFunc(:renderScene) glutIgnoreKeyRepeat(1) glutKeyboardFunc(:processNormalKeys) glutSpecialFunc(:pressKey) glutSpecialUpFunc(:releaseKey) // here are the two new functions glutMouseFunc(:mouseButton) glutMotionFunc(:mouseMove) // OpenGL init glEnable(GL_DEPTH_TEST) // enter GLUT event processing cycle glutMainLoop() 55.12 Menu Events 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 55.12. Menu Events 542