add thrust example

Author: JeffM2501

thrust_motion/README.md

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+# Thrust
+
+Simple example of how to apply thrust, acceleration, and direction based movement over time

thrust_motion/premake5.lua

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+
+baseName = path.getbasename(os.getcwd())
+
+defineWorkspace(baseName)

thrust_motion/resources/License.txt

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+	
+
+	Simple Space (1.0)
+
+	Created/distributed by Kenney (www.kenney.nl)
+	Creation date: 03-03-2021
+
+			------------------------------
+
+	License: (Creative Commons Zero, CC0)
+	http://creativecommons.org/publicdomain/zero/1.0/
+
+	This content is free to use in personal, educational and commercial projects.
+	Support us by crediting Kenney or www.kenney.nl (this is not mandatory)
+
+			------------------------------
+
+	Donate:   http://support.kenney.nl
+	Patreon:  http://patreon.com/kenney/
+
+	Follow on Twitter for updates:
+	http://twitter.com/KenneyNL

thrust_motion/resources/ship.png

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+/*
+Raylib thruster example
+Simple example showing the math for thrust based motion
+*/
+
+#include "raylib.h"
+#include "raymath.h"
+
+bool SearchAndSetResourceDir(const char* folderName);
+
+int main()
+{
+	// set up the window
+	InitWindow(1280, 800, "In Thust We Trust");
+	SetTargetFPS(240);
+	SearchAndSetResourceDir("resources");
+	Texture ship = LoadTexture("Ship.png");
+
+	float shipAngle = -90; // default graphic faces in the Y- direction so that is -90 degrees
+	Vector2 shipPosition = { GetScreenWidth() * 0.5f, GetScreenHeight() * 0.5f };	// center us in the screen
+	Vector2 shipVelocity = { 0,0 };	// we start not moving
+
+	// game loop
+	while (!WindowShouldClose())
+	{
+		// rotation
+		float rotationDelta = 180.0f * GetFrameTime();
+		if (IsKeyDown(KEY_A))
+			shipAngle -= rotationDelta;
+		if (IsKeyDown(KEY_D))
+			shipAngle += rotationDelta;
+		
+		// compute the facing vector of the ship from the angle, the 
+		Vector2 shipFacing = (Vector2){ cosf((shipAngle) * DEG2RAD), sinf((shipAngle) * DEG2RAD) };
+
+		// thrust
+		// compute the thrust(acceleration) to add this frame (use time)
+		float thrustAmount = 0;
+		if (IsKeyDown(KEY_W))
+			thrustAmount = 300 * GetFrameTime();
+
+		// see how much thrust we are going to add to our motion vector
+		Vector2 thrustVector = Vector2Scale(shipFacing, thrustAmount);
+
+		// add thrust to our velocity (units/second)
+		shipVelocity = Vector2Add(shipVelocity, thrustVector);
+
+		// clamp the velocity to some sane limit
+		if (Vector2Length(shipVelocity) > 1000)
+			shipVelocity = Vector2Scale(Vector2Normalize(shipVelocity), 1000);
+
+		// if you want to add some friction, do it here, slowly reduce the lenght of shipVelocity
+
+		// position
+		// update our position based on our velocity for this frame
+		shipPosition = Vector2Add(shipPosition, Vector2Scale(shipVelocity, GetFrameTime()));
+
+		// collisions
+		float radius = 25;
+
+		if (shipPosition.x - radius < 0)
+		{
+			// we hit the left edge, bounce
+			shipPosition.x = 0 + radius;
+			shipVelocity.x *= -1;
+		}
+
+		if (shipPosition.x + radius > GetScreenWidth())
+		{
+			// we hit the right edge, bounce
+			shipPosition.x = GetScreenWidth() - radius;
+			shipVelocity.x *= -1;
+		}
+
+		if (shipPosition.y - radius < 0)
+		{
+			// we hit the top edge, bounce
+			shipPosition.y = 0 + radius;
+			shipVelocity.y *= -1;
+		}
+
+		if (shipPosition.y + radius > GetScreenHeight())
+		{
+			// we hit the top edge, bounce
+			shipPosition.y = GetScreenHeight() - radius;
+			shipVelocity.y *= -1;
+		}
+
+		BeginDrawing();
+		ClearBackground(DARKGRAY);
+
+		DrawRectangleLinesEx((Rectangle){ 1,1,GetScreenWidth()-1,GetScreenHeight()-1 }, 3, RED);
+
+		// draw the ship centered
+		DrawTexturePro(ship,
+			(Rectangle) { 0, 0, ship.width, ship.height },
+			(Rectangle) { shipPosition.x, shipPosition.y, ship.width, ship.height },
+			(Vector2) { ship.width * 0.5f, ship.height * 0.5f },
+			shipAngle+90 /*compensate for our rotated ship graphic*/,
+			WHITE);
+
+		DrawLineEx(shipPosition, Vector2Add(shipPosition, Vector2Scale(shipFacing, 100)), 2, PURPLE);
+
+		EndDrawing();
+	}
+
+	UnloadTexture(ship);
+	// cleanup
+	CloseWindow();
+	return 0;
+}
+
+
+bool SearchAndSetResourceDir(const char* folderName)
+{
+	// check the working dir
+	if (DirectoryExists(folderName))
+	{
+		ChangeDirectory(TextFormat("%s/%s", GetWorkingDirectory(), folderName));
+		return true;
+	}
+
+	const char* appDir = GetApplicationDirectory();
+
+	// check the applicationDir
+	const char* dir = TextFormat("%s%s", appDir, folderName);
+	if (DirectoryExists(dir))
+	{
+		ChangeDirectory(dir);
+		return true;
+	}
+
+	// check one up from the app dir
+	dir = TextFormat("%s../%s", appDir, folderName);
+	if (DirectoryExists(dir))
+	{
+		ChangeDirectory(dir);
+		return true;
+	}
+
+	// check two up from the app dir
+	dir = TextFormat("%s../../%s", appDir, folderName);
+	if (DirectoryExists(dir))
+	{
+		ChangeDirectory(dir);
+		return true;
+	}
+
+	// check three up from the app dir
+	dir = TextFormat("%s../../../%s", appDir, folderName);
+	if (DirectoryExists(dir))
+	{
+		ChangeDirectory(dir);
+		return true;
+	}
+
+	return false;
+}