The Ring programming language version 1.6 book - Part 10 of 189
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The document describes code for a 3D graphics application using OpenGL and RingFreeGLUT. It includes functions for rendering a scene with 9 snowmen on a ground plane, handling user input for camera movement and rotation, and displaying frames per second. Keyboard, mouse, and menu callbacks are defined to control movement, rotation, and settings like polygon mode, color, and font. The main function initializes GLUT, registers the callbacks, and enters the event loop.
The Ring programming language version 1.6 book - Part 10 of 189
- 1. Ring Documentation, Release 1.6 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 9 SnowMen for i = -3 to -1 for j = -3 to -1 glPushMatrix() glTranslatef(i*10.0, 0.0, j * 10.0) drawSnowMan() number = (i+3)*3+(j+3) renderBitmapString(0.0, 0.5, 0.0,font ,""+number) glPopMatrix() next next // Code to compute frames per second frame++ time=glutGet(GLUT_ELAPSED_TIME) if time - timebase > 1000 s = "RingFreeGLUT - FPS: " + (frame*1000.0/(time-timebase)) timebase = time frame = 0 ok // Code to display a string (fps) with bitmap fonts setOrthographicProjection() glPushMatrix() glLoadIdentity() 5.10. RingFreeGLUT Extension 63
- 2. Ring Documentation, Release 1.6 renderBitmapString(5,30,0,GLUT_BITMAP_HELVETICA_18,s) glPopMatrix() restorePerspectiveProjection() glutSwapBuffers() // ----------------------------------- // KEYBOARD // ----------------------------------- func processNormalKeys key = glutEventKey() xx = glutEventX() yy = glutEventY() switch key on 27 glutDestroyMenu(mainMenu) glutDestroyMenu(fillMenu) glutDestroyMenu(colorMenu) glutDestroyMenu(fontMenu) Shutdown() off func pressKey key = glutEventKey() xx = glutEventX() yy = glutEventY() 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 // ----------------------------------- // MOUSE // ----------------------------------- func mouseMove 5.10. RingFreeGLUT Extension 64
- 3. Ring Documentation, Release 1.6 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 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 ok // ----------------------------------- // MENUS // ----------------------------------- func processMenuStatus status = glutEventStatus() if status = GLUT_MENU_IN_USE menuFlag = 1 else menuFlag = 0 ok func processMainMenu // nothing to do in here // all actions are for submenus func processFillMenu 5.10. RingFreeGLUT Extension 65
- 4. Ring Documentation, Release 1.6 option = glutEventValue() switch option on C_FILL glPolygonMode(GL_FRONT, GL_FILL) on C_LINE glPolygonMode(GL_FRONT, GL_LINE) off func processFontMenu option = glutEventValue() switch (option) { on C_INT_GLUT_BITMAP_8_BY_13 font = GLUT_BITMAP_8_BY_13 on C_INT_GLUT_BITMAP_9_BY_15 font = GLUT_BITMAP_9_BY_15 on C_INT_GLUT_BITMAP_TIMES_ROMAN_10 font = GLUT_BITMAP_TIMES_ROMAN_10 on C_INT_GLUT_BITMAP_TIMES_ROMAN_24 font = GLUT_BITMAP_TIMES_ROMAN_24 on C_INT_GLUT_BITMAP_HELVETICA_10 font = GLUT_BITMAP_HELVETICA_10 on C_INT_GLUT_BITMAP_HELVETICA_12 font = GLUT_BITMAP_HELVETICA_12 on C_INT_GLUT_BITMAP_HELVETICA_18 font = GLUT_BITMAP_HELVETICA_18 off func processColorMenu option = glutEventValue() switch option on C_RED red = 1.0 green = 0.0 blue = 0.0 on C_GREEN red = 0.0 green = 1.0 blue = 0.0 on C_BLUE red = 0.0 green = 0.0 blue = 1.0 on C_ORANGE red = 1.0 green = 0.5 blue = 0.5 off func createPopupMenus 5.10. RingFreeGLUT Extension 66
- 5. Ring Documentation, Release 1.6 fontMenu = glutCreateMenu(:processFontMenu) glutAddMenuEntry("BITMAP_8_BY_13 ",C_INT_GLUT_BITMAP_8_BY_13 ) glutAddMenuEntry("BITMAP_9_BY_15",C_INT_GLUT_BITMAP_9_BY_15 ) glutAddMenuEntry("BITMAP_TIMES_ROMAN_10 ",C_INT_GLUT_BITMAP_TIMES_ROMAN_10 ) glutAddMenuEntry("BITMAP_TIMES_ROMAN_24",C_INT_GLUT_BITMAP_TIMES_ROMAN_24 ) glutAddMenuEntry("BITMAP_HELVETICA_10 ",C_INT_GLUT_BITMAP_HELVETICA_10 ) glutAddMenuEntry("BITMAP_HELVETICA_12",C_INT_GLUT_BITMAP_HELVETICA_12 ) glutAddMenuEntry("BITMAP_HELVETICA_18",C_INT_GLUT_BITMAP_HELVETICA_18 ) fillMenu = glutCreateMenu(:processFillMenu) glutAddMenuEntry("Fill",C_FILL) glutAddMenuEntry("Line",C_LINE) colorMenu = glutCreateMenu(:processColorMenu) glutAddMenuEntry("Red",C_RED); glutAddMenuEntry("Blue",C_BLUE); glutAddMenuEntry("Green",C_GREEN); glutAddMenuEntry("Orange",C_ORANGE); mainMenu = glutCreateMenu(:processMainMenu) glutAddSubMenu("Polygon Mode", fillMenu) glutAddSubMenu("Color", colorMenu) glutAddSubMenu("Font",fontMenu) // attach the menu to the right button glutAttachMenu(GLUT_RIGHT_BUTTON) // this will allow us to know if the menu is active glutMenuStatusFunc(:processMenuStatus) // ----------------------------------- // MAIN // ----------------------------------- 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 SnowMan") // register callbacks glutDisplayFunc(:renderScene) glutReshapeFunc(:changeSize) glutIdleFunc(:renderScene) glutIgnoreKeyRepeat(1) glutKeyboardFunc(:processNormalKeys) glutSpecialFunc(:pressKey) glutSpecialUpFunc(:releaseKey) // here are the two new functions glutMouseFunc(:mouseButton) 5.10. RingFreeGLUT Extension 67
- 6. Ring Documentation, Release 1.6 glutMotionFunc(:mouseMove) // OpenGL init glEnable(GL_DEPTH_TEST) glEnable(GL_CULL_FACE) // init Menus createPopupMenus() // enter GLUT event processing cycle glutMainLoop() Screen Shots: 5.10. RingFreeGLUT Extension 68
- 7. Ring Documentation, Release 1.6 5.11 RingOpenGL Extension Ring 1.5 comes with RingOpenGL and support for the next versions • OpenGL 1.1 • OpenGL 1.2 • OpenGL 1.3 • OpenGL 1.4 • OpenGL 1.5 • OpenGL 2.0 • OpenGL 2.1 • OpenGL 3.0 • OpenGL 3.2 • OpenGL 3.3 • OpenGL 4.0 • OpenGL 4.1 • OpenGL 4.2 • OpenGL 4.3 • OpenGL 4.4 • OpenGL 4.5 • OpenGL 4.6 Example: /* This sample is based on C Tutorials from : http://www.wikihow.com/Make-a-Cube-in-OpenGL */ load "freeglut.ring" load "opengl21lib.ring" // ---------------------------------------------------------- // Global Variables // ---------------------------------------------------------- rotate_y=0 rotate_x=0 // ---------------------------------------------------------- // display() Callback function // ---------------------------------------------------------- func display // Clear screen and Z-buffer glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) // Reset transformations 5.11. RingOpenGL Extension 69
- 8. Ring Documentation, Release 1.6 glLoadIdentity() // Rotate when user changes rotate_x and rotate_y glRotatef( rotate_x, 1.0, 0.0, 0.0 ) glRotatef( rotate_y, 0.0, 1.0, 0.0 ) //Multi-colored side - FRONT glBegin(GL_POLYGON) glColor3f( 1.0, 0.0, 0.0 ) glVertex3f( 0.5, -0.5, -0.5 ) # P1 is red glColor3f( 0.0, 1.0, 0.0 ) glVertex3f( 0.5, 0.5, -0.5 ) # P2 is green glColor3f( 0.0, 0.0, 1.0 ) glVertex3f( -0.5, 0.5, -0.5 ) # P3 is blue glColor3f( 1.0, 0.0, 1.0 ) glVertex3f( -0.5, -0.5, -0.5 ) # P4 is purple glEnd() // White side - BACK glBegin(GL_POLYGON) glColor3f( 1.0, 1.0, 1.0 ) glVertex3f( 0.5, -0.5, 0.5 ) glVertex3f( 0.5, 0.5, 0.5 ) glVertex3f( -0.5, 0.5, 0.5 ) glVertex3f( -0.5, -0.5, 0.5 ) glEnd() // Purple side - RIGHT glBegin(GL_POLYGON) glColor3f( 1.0, 0.0, 1.0 ) glVertex3f( 0.5, -0.5, -0.5 ) glVertex3f( 0.5, 0.5, -0.5 ) glVertex3f( 0.5, 0.5, 0.5 ) glVertex3f( 0.5, -0.5, 0.5 ) glEnd() // Green side - LEFT glBegin(GL_POLYGON) glColor3f( 0.0, 1.0, 0.0 ) glVertex3f( -0.5, -0.5, 0.5 ) glVertex3f( -0.5, 0.5, 0.5 ) glVertex3f( -0.5, 0.5, -0.5 ) glVertex3f( -0.5, -0.5, -0.5 ) glEnd() // Blue side - TOP glBegin(GL_POLYGON) glColor3f( 0.0, 0.0, 1.0 ) glVertex3f( 0.5, 0.5, 0.5 ) glVertex3f( 0.5, 0.5, -0.5 ) glVertex3f( -0.5, 0.5, -0.5 ) glVertex3f( -0.5, 0.5, 0.5 ) glEnd() // Red side - BOTTOM glBegin(GL_POLYGON) glColor3f( 1.0, 0.0, 0.0 ) glVertex3f( 0.5, -0.5, -0.5 ) glVertex3f( 0.5, -0.5, 0.5 ) glVertex3f( -0.5, -0.5, 0.5 ) 5.11. RingOpenGL Extension 70
- 9. Ring Documentation, Release 1.6 glVertex3f( -0.5, -0.5, -0.5 ) glEnd() glFlush() glutSwapBuffers() // ---------------------------------------------------------- // specialKeys() Callback Function // ---------------------------------------------------------- func specialKeys key = glutEventKey() // Right arrow - increase rotation by 5 degree switch Key on GLUT_KEY_RIGHT rotate_y += 5 // Left arrow - decrease rotation by 5 degree on GLUT_KEY_LEFT rotate_y -= 5 on GLUT_KEY_UP rotate_x += 5 on GLUT_KEY_DOWN rotate_x -= 5 off // Request display update glutPostRedisplay() // ---------------------------------------------------------- // main() function // ---------------------------------------------------------- func main // Initialize GLUT and process user parameters glutInit() // Request double buffered true color window with Z-buffer glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH) // Create window glutCreateWindow("Awesome Cube") // Enable Z-buffer depth test glEnable(GL_DEPTH_TEST) // Callback functions glutDisplayFunc(:display) glutSpecialFunc(:specialKeys) 5.11. RingOpenGL Extension 71
- 10. Ring Documentation, Release 1.6 // Pass control to GLUT for events glutMainLoop() // Return to OS Screen Shot: 5.12 Better Code Generator for Extensions The Code Generator is updated to support <constant> type, So we can have constants other than numbers, for example : Strings and Pointers. When we have pointers we can determine the pointer type. To use this feature, before <constant> and </constant> we can use $nDefaultConstantType = C_CONSTANT_TYPE_POINTER $cDefaultConstantPointerType = "void *" The next example from the RingFreeGLUT extension <runcode> $nDefaultConstantType = C_CONSTANT_TYPE_POINTER $cDefaultConstantPointerType = "void" </runcode> <constant> GLUT_STROKE_ROMAN GLUT_STROKE_MONO_ROMAN GLUT_BITMAP_9_BY_15 GLUT_BITMAP_8_BY_13 GLUT_BITMAP_TIMES_ROMAN_10 GLUT_BITMAP_TIMES_ROMAN_24 GLUT_BITMAP_HELVETICA_10 GLUT_BITMAP_HELVETICA_12 5.12. Better Code Generator for Extensions 72