prism/physics.cpp at develop · CaptainDreamcast/prism · GitHub

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#include "prism/physics.h"

#include <string.h>
#include <math.h>

#include "prism/log.h"
#include "prism/system.h"

#ifdef _WIN32
#include <imgui/imgui.h>
#include "prism/windows/debugimgui_win.h"
#endif

namespace prism {

	static struct {
		Velocity mMaxVelocity;
		double mMaxVelocityDouble = INFINITY;
		Gravity mGravity;
		int mIsPaused;
		Vector3D mOneMinusDragCoefficient;
	} gPrismPhysicsData;

#ifdef _WIN32
	void imguiPhysics()
	{
		static bool isWindowShown = false;
		imguiPrismAddTab("Prism", "Physics", &isWindowShown);
		if (isWindowShown)
		{
			ImGui::Begin("Physics", &isWindowShown);
			ImGui::Text("MaxVelocity = %f %f %f", gPrismPhysicsData.mMaxVelocity.x, gPrismPhysicsData.mMaxVelocity.y, gPrismPhysicsData.mMaxVelocity.z);
			ImGui::Text("MaxVelocityDouble = %f", gPrismPhysicsData.mMaxVelocityDouble);
			ImGui::Text("Gravity = %f %f %f", gPrismPhysicsData.mGravity.x, gPrismPhysicsData.mGravity.y, gPrismPhysicsData.mGravity.z);
			ImGui::Text("IsPaused = %d", gPrismPhysicsData.mIsPaused);
			ImGui::Text("OneMinusDragCoefficient = %f %f %f", gPrismPhysicsData.mOneMinusDragCoefficient.x, gPrismPhysicsData.mOneMinusDragCoefficient.y, gPrismPhysicsData.mOneMinusDragCoefficient.z);
			ImGui::End();
		}
	}
#endif

	void setMaxVelocity(const Velocity& tVelocity) {
		gPrismPhysicsData.mMaxVelocity = tVelocity;
	}

	void setMaxVelocityDouble(double tVelocity) {
		gPrismPhysicsData.mMaxVelocityDouble = tVelocity;
	}

	void resetMaxVelocity() {
		Velocity maxVelocity;
		maxVelocity.x = INFINITY;
		maxVelocity.y = INFINITY;
		maxVelocity.z = INFINITY;
		setMaxVelocity(maxVelocity);
		setMaxVelocityDouble(INFINITY);
	}

	void setDragCoefficient(const Vector3D& tDragCoefficient) {
		gPrismPhysicsData.mOneMinusDragCoefficient = vecAdd(Vector3D(1, 1, 1), vecScale(tDragCoefficient, -1));
	}

	void resetDragCoefficient() {
		gPrismPhysicsData.mOneMinusDragCoefficient = Vector3D(1, 1, 1);
	}

	void setGravity(const Gravity& tGravity) {
		gPrismPhysicsData.mGravity = tGravity;
	}

	Gravity getGravity() {
		return gPrismPhysicsData.mGravity;
	}

	static double f_min(double a, double b) {
		return (a < b) ? a : b;
	}

	static double f_max(double a, double b) {
		return (a > b) ? a : b;
	}

	void handlePhysics(PhysicsObject* tObject) {
		if (gPrismPhysicsData.mIsPaused) return;
		tObject->mPosition.x += tObject->mVelocity.x;
		tObject->mPosition.y += tObject->mVelocity.y;
		tObject->mPosition.z += tObject->mVelocity.z;

		tObject->mVelocity.x *= gPrismPhysicsData.mOneMinusDragCoefficient.x;
		tObject->mVelocity.y *= gPrismPhysicsData.mOneMinusDragCoefficient.y;
		tObject->mVelocity.z *= gPrismPhysicsData.mOneMinusDragCoefficient.z;

		double f = getFramerateFactor();
		tObject->mVelocity.x += tObject->mAcceleration.x * f;
		tObject->mVelocity.y += tObject->mAcceleration.y * f;
		tObject->mVelocity.z += tObject->mAcceleration.z * f;

		tObject->mVelocity.x = f_max(-gPrismPhysicsData.mMaxVelocity.x * f, f_min(gPrismPhysicsData.mMaxVelocity.x * f, tObject->mVelocity.x));
		tObject->mVelocity.y = f_max(-gPrismPhysicsData.mMaxVelocity.y, f_min(gPrismPhysicsData.mMaxVelocity.y, tObject->mVelocity.y));
		tObject->mVelocity.z = f_max(-gPrismPhysicsData.mMaxVelocity.x, f_min(gPrismPhysicsData.mMaxVelocity.z, tObject->mVelocity.z));
		if (vecLength(tObject->mVelocity) > gPrismPhysicsData.mMaxVelocityDouble) {
			tObject->mVelocity = vecNormalize(tObject->mVelocity) * gPrismPhysicsData.mMaxVelocityDouble * f;
		}

		tObject->mAcceleration.x = gPrismPhysicsData.mGravity.x;
		tObject->mAcceleration.y = gPrismPhysicsData.mGravity.y;
		tObject->mAcceleration.z = gPrismPhysicsData.mGravity.z;
	}

	void resetPhysicsObject(PhysicsObject* tObject) {
		memset((void*)tObject, 0, sizeof(PhysicsObject));
	}

	void resetPhysics() {
		resetMaxVelocity();
		resetDragCoefficient();

		Gravity gravity;
		gravity.x = 0;
		gravity.y = 0;
		gravity.z = 0;
		setGravity(gravity);

		gPrismPhysicsData.mIsPaused = 0;
	}

	void initPhysics() {
		resetPhysics();
	}

	void pausePhysics() {
		gPrismPhysicsData.mIsPaused = 1;
	}
	void resumePhysics() {
		gPrismPhysicsData.mIsPaused = 0;
	}

	int isEmptyVelocity(const Velocity& tVelocity) {
		return tVelocity.x == 0 && tVelocity.y == 0 && tVelocity.z == 0;
	}
	Velocity normalizeVelocity(const Velocity& tVelocity) {
		return vecNormalize(tVelocity);
	}

}