VehicleEngine.cpp 3.5 KB

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  1. // SPDX-FileCopyrightText: 2021 Jorrit Rouwe
  2. // SPDX-License-Identifier: MIT
  3. #include <Jolt/Jolt.h>
  4. #include <Jolt/Physics/Vehicle/VehicleEngine.h>
  5. #include <Jolt/ObjectStream/TypeDeclarations.h>
  6. #ifdef JPH_DEBUG_RENDERER
  7. #include <Jolt/Renderer/DebugRenderer.h>
  8. #endif // JPH_DEBUG_RENDERER
  9. JPH_NAMESPACE_BEGIN
  10. JPH_IMPLEMENT_SERIALIZABLE_NON_VIRTUAL(VehicleEngineSettings)
  11. {
  12. JPH_ADD_ATTRIBUTE(VehicleEngineSettings, mMaxTorque)
  13. JPH_ADD_ATTRIBUTE(VehicleEngineSettings, mMinRPM)
  14. JPH_ADD_ATTRIBUTE(VehicleEngineSettings, mMaxRPM)
  15. JPH_ADD_ATTRIBUTE(VehicleEngineSettings, mNormalizedTorque)
  16. }
  17. VehicleEngineSettings::VehicleEngineSettings()
  18. {
  19. mNormalizedTorque.Reserve(3);
  20. mNormalizedTorque.AddPoint(0.0f, 0.8f);
  21. mNormalizedTorque.AddPoint(0.66f, 1.0f);
  22. mNormalizedTorque.AddPoint(1.0f, 0.8f);
  23. }
  24. void VehicleEngineSettings::SaveBinaryState(StreamOut &inStream) const
  25. {
  26. inStream.Write(mMaxTorque);
  27. inStream.Write(mMinRPM);
  28. inStream.Write(mMaxRPM);
  29. mNormalizedTorque.SaveBinaryState(inStream);
  30. }
  31. void VehicleEngineSettings::RestoreBinaryState(StreamIn &inStream)
  32. {
  33. inStream.Read(mMaxTorque);
  34. inStream.Read(mMinRPM);
  35. inStream.Read(mMaxRPM);
  36. mNormalizedTorque.RestoreBinaryState(inStream);
  37. }
  38. void VehicleEngine::ApplyTorque(float inTorque, float inDeltaTime)
  39. {
  40. // Accelerate engine using torque
  41. mCurrentRPM += cAngularVelocityToRPM * inTorque * inDeltaTime / mInertia;
  42. ClampRPM();
  43. }
  44. void VehicleEngine::ApplyDamping(float inDeltaTime)
  45. {
  46. // Angular damping: dw/dt = -c * w
  47. // Solution: w(t) = w(0) * e^(-c * t) or w2 = w1 * e^(-c * dt)
  48. // Taylor expansion of e^(-c * dt) = 1 - c * dt + ...
  49. // Since dt is usually in the order of 1/60 and c is a low number too this approximation is good enough
  50. mCurrentRPM *= max(0.0f, 1.0f - mAngularDamping * inDeltaTime);
  51. ClampRPM();
  52. }
  53. #ifdef JPH_DEBUG_RENDERER
  54. void VehicleEngine::DrawRPM(DebugRenderer *inRenderer, Vec3Arg inPosition, Vec3Arg inForward, Vec3Arg inUp, float inSize, float inShiftDownRPM, float inShiftUpRPM) const
  55. {
  56. // Function that converts RPM to an angle in radians
  57. auto rpm_to_angle = [this](float inRPM) { return (-0.75f + 1.5f * (inRPM - mMinRPM) / (mMaxRPM - mMinRPM)) * JPH_PI; };
  58. // Function to draw part of a pie
  59. auto draw_pie = [rpm_to_angle, inRenderer, inSize, inPosition, inForward, inUp](float inMinRPM, float inMaxRPM, Color inColor) {
  60. inRenderer->DrawPie(inPosition, inSize, inForward, inUp, rpm_to_angle(inMinRPM), rpm_to_angle(inMaxRPM), inColor, DebugRenderer::ECastShadow::Off);
  61. };
  62. // Draw segment until inShiftDownRPM
  63. if (mCurrentRPM < inShiftDownRPM)
  64. {
  65. draw_pie(mMinRPM, mCurrentRPM, Color::sRed);
  66. draw_pie(mCurrentRPM, inShiftDownRPM, Color::sDarkRed);
  67. }
  68. else
  69. {
  70. draw_pie(mMinRPM, inShiftDownRPM, Color::sRed);
  71. }
  72. // Draw segment between inShiftDownRPM and inShiftUpRPM
  73. if (mCurrentRPM > inShiftDownRPM && mCurrentRPM < inShiftUpRPM)
  74. {
  75. draw_pie(inShiftDownRPM, mCurrentRPM, Color::sOrange);
  76. draw_pie(mCurrentRPM, inShiftUpRPM, Color::sDarkOrange);
  77. }
  78. else
  79. {
  80. draw_pie(inShiftDownRPM, inShiftUpRPM, mCurrentRPM <= inShiftDownRPM? Color::sDarkOrange : Color::sOrange);
  81. }
  82. // Draw segment above inShiftUpRPM
  83. if (mCurrentRPM > inShiftUpRPM)
  84. {
  85. draw_pie(inShiftUpRPM, mCurrentRPM, Color::sGreen);
  86. draw_pie(mCurrentRPM, mMaxRPM, Color::sDarkGreen);
  87. }
  88. else
  89. {
  90. draw_pie(inShiftUpRPM, mMaxRPM, Color::sDarkGreen);
  91. }
  92. }
  93. #endif // JPH_DEBUG_RENDERER
  94. void VehicleEngine::SaveState(StateRecorder &inStream) const
  95. {
  96. inStream.Write(mCurrentRPM);
  97. }
  98. void VehicleEngine::RestoreState(StateRecorder &inStream)
  99. {
  100. inStream.Read(mCurrentRPM);
  101. }
  102. JPH_NAMESPACE_END