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Wiki source code of Ball Physics

Version 6.1 by stu104225 on 2020/03/04 17:32
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stu104225 5.1 1 The **ball physics model** is meant to do things ... [TODO]
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stu104225 1.1 3 \\
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stu104225 5.1 7 {{toc/}}
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stu104225 4.1 9 == Ball trajectory ==
stu104225 1.1 10
stu104225 5.1 11 ----
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stu104225 4.1 13 The trajectory of a ball can be modeled to be parabolic.
stu104225 5.1 14 \\\\\\like so: .... [TODO]
stu104225 4.1 15
stu104225 1.1 16 == Configuration ==
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stu104225 5.1 18 ----
stu104225 1.1 19
stu104225 5.1 20 === Prediction parameters ===
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stu104225 6.1 22 (% class="wrapped" %)
stu104225 5.1 23 |=(((
24 Parameter
25 )))|=(((
26 Description
27 )))|=(((
28 Default value
29 )))
30 |(((
31 PREDICTION_FRAME
32 )))|(((
33 window size for prediction - How far
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35 into the future are predctions calculated at most.
36 )))|(((
37 70ms
38 )))
39 |(((
40 PREDICTION_STEP_SIZE
41 )))|(((
42 size of the steps for the forward search
43 )))|(((
44 10ms
45 )))
46 |(((
47 REFINEMENT_FACTOR
48 )))|(((
49 The prediction step size for the reverse search is
50 PREDICTION_STEP_SIZE divided by REFINEMENT_FACTOR.
51 )))|(((
52 10
53 )))
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stu104225 6.1 55 When setting the PREDICTION_FRAME keep in mind, that predictions, that reach multiple frames into the future, are likely to be overwritten, when new frames arrive and new predictions are calculated.
56 Nevertheless it is reasonable to calculate predictions beyond the next frame in case a ball is not recognized on the next frame.
stu104225 5.1 57
stu104225 6.1 58 With the default values up to 7 predictions are calculated if the ball is not predicted to be in flipper range roughly within the next two frames.
stu104225 5.1 59
stu104225 6.1 60 The REFINEMENT_FACTOR is also the worst case number of predictions calculated during the reverse search part of the prediction process.
stu104225 5.1 61
62 \\
63
64 === Flipper range ===
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stu104225 4.1 66 The model of the area, where the the flippers can hit a ball is computed from a set of five points. These points are set to real world coordinates in meter
stu104225 1.1 67
stu104225 4.1 68 and should not need further adjustment after the camera is correctly calibrated (see [[doc:World Coordinate System]]).
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stu104225 5.1 70 The values for the left flipper are set to be symmetrical.
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stu104225 1.1 72 [[image:attach:physics_points.png]]
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stu104225 5.1 74 (% class="wrapped" %)
stu104225 4.1 75 |=(((
76 Point#
77 )))|=(((
78 Description
79 )))
80 |(((
81 1
82 )))|(((
83 center point of the circle that the flippers tip moves o
84 )))
85 |(((
86 2
87 )))|(((
88 highest point a ball can be at when it hits the resting flipper
89 )))
90 |(((
91 3
92 )))|(((
93 lowest point a ball can be at when it hits the resting flipper
94 )))
95 |(((
96 4
97 )))|(((
98 lowest point a ball can be at when it hits the fully triggered flipper
99 )))
100 |(((
101 5
102 )))|(((
103 highest point a ball can be at when it hits the fully triggered flipper
104 )))
stu104225 1.1 105
106 \\
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stu104225 5.1 108 From these points an area, where the ball is deemed to be hittable, is computed.
stu104225 4.1 109
stu104225 1.1 110 [[image:attach:physics2.png]]
111
112 \\
113
114 === Inlane Area ===
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stu104225 5.1 116 Since the trajectory prediction does not consider collisions in general, we need a different kind of predictions for the inlanes,
117 i.e. the path feeding a falling ball from the playfield to the flippers, behind the slingshot.
118 A ball is considered to be in an inlane, when it is in a rectangualar area, with one edge given by the begin of the flipper
119 and the other by a point at highest, outermost position of the angled part of the inlane.
stu104225 4.1 120
stu104225 6.1 121 In this area the vertical accelleration is deactivated in the prediction, since it would cause the prediction to assume the would slide into the wall.
122 Though in reality the still is some accelleration, a simple linear prediction has shown to be practical in this less critical area.
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stu104225 1.1 124 [[image:attach:physics_inlane.png]]