Hands On DarkBASIC Pro - Digital Skills

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FIG-30.4 (continued) Determining the Position of a Point in 3D Space FIG-30.5 Each Object has its Own Local Axes World Units Local Axes -x 3 Measure the point’s distance out from the origin-z along the z-axis -x +y -y We might, for example, state that point p is at the position (8,12,5) meaning that point p is 8 units along the x-axis, 12 units along the y-axis and 5 units along the z-axis. Distances are measured in units. These units have no relationship to real-life measurements such as centimetres or inches. Instead, objects are constructed in such a way as to be the correct size relative to other objects. For example, if we make a human character 6 units high, then a simple house might be 18 to 25 units high. Of course, if you wish, you can think of 1 unit being the equivalent of a real distance. The scale you choose will depend on the context; when creating a world with an ant as the main character, 1 unit might be equivalent to a millimetre, while a truly interstellar game might make 1 unit equivalent to 1 light year. Every 3D object we create has its own local axes. These axes are (initially, at least) aligned to the world axes. FIG-30.5 shows a cuboid and its local axes. -x -z +y -y +z +z P Each 3D object has its own local axes parallel to the world axes DarkBASIC Pro: 3D - Concepts and Terminology 747 +x +x
FIG-30.6 Rotation A Cuboid is Rotated 30 o about the x-axis FIG-30.7 Clockwise Rotation 3D Vectors FIG-30.8 The MAKE VECTOR3 Statement An object can be made to rotate about its own, local, axes. In DarkBASIC Pro rotation is measured in degrees. For example, we might rotate an object 30 degrees about it's x-axis as shown in FIG-30.6. Initial Position Z-axis Rotation is performed in a clockwise direction when viewed down the positive end of an axis (see FIG-30.7). By specifying a negative angle of rotation, an object will rotate anti-clockwise. Although the purpose of this chapter is to describe basic 3D concepts, it's worth mentioning that DarkBASIC Pro allows the creation of a 3-element vector specifically for storing the coordinates of a point in 3D space. The vector is created using the MAKE VECTOR3 statement which has the format shown in FIG-30.8. In the diagram: Y-axis Axis vectno is an integer value giving the ID to be assigned to the 3D vector being created. The statement returns 1 if the vector is created successfully; otherwise zero is returned. Usually we won't worry about the value returned and can create a 3D vector with a statement such as: result = MAKE VECTOR3(1) X-axis Rotation is in a clockwise direction o Rotated 30 about the x-axis Y-axis Z-axis X-axis when viewed from the positive end of an axis VECTOR3 ( ) MAKE VECTOR3 vectno integer 748 DarkBASIC Pro: 3D - Concepts and Terminology
Page 1 and 2: Hands On DarkBASIC Pro A Self-Study
Page 3 and 4: Copyright © Alistair Stewart 2006
Page 5 and 6: The TURN OBJECT Statement . . . . .
Page 7 and 8: The YROTATE CAMERA Statement . . .
Page 9 and 10: Chapter 35 Meshes and Limbs Meshes.
Page 11 and 12: The OBJECT IN SCREEN Statement . .
Page 13 and 14: The MAKE OBJECT COLLISION BOX State
Page 15 and 16: Adding MoveElevator() . . . . . . .
Page 17 and 18: The RANDOMIZE MATRIX Statement . .
Page 19 and 20: The MAKE MEMBLOCK FROM SOUND Statem
Page 21 and 22: The TRANSPOSE MATRIX4 Statement . .
Page 23 and 24: Networking the Game . . . . . . . .
Page 25 and 26: Acknowledgements I would like to th
Page 27 and 28: Syntax Diagrams make only a half-he
Page 29 and 30: The 3D World Introduction The Coord
Page 31: FIG-30.4 Points Determining the Pos
Page 35 and 36: FIG-30.13 Varying the Polygons in a
Page 37 and 38: FIG-30.17 Lights Surface Normals FI
Page 39 and 40: � Space within the 3D world is me
Page 41 and 42: 3D Primitives Introduction FIG-31.1
Page 43 and 44: FIG-31.5 The MAKE OBJECT BOX Statem
Page 45 and 46: FIG-31.9 The MAKE OBJECT CONE State
Page 47 and 48: FIG-31.13 Creating a Triangle Objec
Page 49 and 50: FIG-31.16 The MOVE OBJECT Statement
Page 51 and 52: FIG-31.19 Possible Rotations about
Page 53 and 54: LISTING-31.3 Rotating an Object abo
Page 55 and 56: FIG-31.29 The PITCH OBJECT Statemen
Page 57 and 58: FIG-31.32 The POINT OBJECT Statemen
Page 59 and 60: LISTING-31.6 (continued) Local Axes
Page 61 and 62: LISTING-31.7 Resizing an Object REM
Page 63 and 64: Copying a 3D Object FIG-31.43 The C
Page 65 and 66: FIG-31.46 FIG-31.47 The OBJECT POSI
Page 67 and 68: FIG-31.49 The OBJECT ANGLE Statemen
Page 69 and 70: LISTING-31.11 (continued) Switching
Page 71 and 72: FIG-31.53 The SET GLOBAL OBJECT CRE
Page 73 and 74: Merging Primitives Introduction FIG
Page 75 and 76: FIG-31.58 As you've just discovered
Page 77 and 78: Solutions Activity 31.1 No solution
Page 79 and 80: Activity 31.20 The duplicated cube
Page 81 and 82: 796 DarkBASIC Pro: 3D Primitives
Page 83 and 84:
Adding Texture Introduction FIG-32.
Page 85 and 86:
FIG-32.3 An Image with Added Mipmap
Page 87 and 88:
FIG-32.5 Floor Texturing FIG-32.6 T
Page 89 and 90:
Seamless Tiling FIG-32.10 A Visible
Page 91 and 92:
FIG-32.12 The PLAY ANIMATION TO IMA
Page 93 and 94:
LISTING-32.6 (continued) Using the
Page 95 and 96:
The SET OBJECT TRANSPARENCY Stateme
Page 97 and 98:
LISTING-32.9 Using a Secondary Text
Page 99 and 100:
LISTING-32.10 (continued) Using the
Page 101 and 102:
FIG-32.24 A Transparent Cube Activi
Page 103 and 104:
FIG-32.27 The FADE OBJECT Statement
Page 105 and 106:
Images with an Alpha Channel Introd
Page 107 and 108:
Creating a Complex 3D Shape Introdu
Page 109 and 110:
The Code LISTING-32.15 Drawing the
Page 111 and 112:
LISTING-32.15 (continued) Drawing t
Page 113 and 114:
Sky Spheres FIG-32.32 Using a Sky S
Page 115 and 116:
Summary To cure the problem of an i
Page 117 and 118:
REM *** Create and texture plain ob
Page 119:
TEXTURE OBJECT GroundObj,CobbleImg
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