raylib-cs/Examples/physac/physics_friction.cs

using Raylib;
using static Raylib.Raylib;

public partial class physics_friction
{
    /*******************************************************************************************
    *
    *   Physac - Physics friction
    *
    *   NOTE 1: Physac requires multi-threading, when InitPhysics() a second thread is created to manage physics calculations.
    *   NOTE 2: Physac requires static C library linkage to avoid dependency on MinGW DLL (-static -lpthread)
    *
    *   Use the following line to compile:
    *
    *   gcc -o $(NAME_PART).exe $(FILE_NAME) -s $(RAYLIB_DIR)\raylib\raylib.rc.o -static -lraylib -lpthread
    *   -lglfw3 -lopengl32 -lgdi32 -lopenal32 -lwinmm -std=c99 -Wl,--subsystem,windows -Wl,-allow-multiple-definition
    *
    *   Copyright (c) 2016-2018 Victor Fisac
    *
    ********************************************************************************************/



    public static int Main()
    {
        // Initialization
        //--------------------------------------------------------------------------------------
        int screenWidth = 800;
        int screenHeight = 450;

        SetConfigFlags(FLAG_MSAA_4X_HINT);
        InitWindow(screenWidth, screenHeight, "Physac [raylib] - Physics friction");

        // Physac logo drawing position
        int logoX = screenWidth - MeasureText("Physac", 30) - 10;
        int logoY = 15;

        // Initialize physics and default physics bodies
        InitPhysics();

        // Create floor rectangle physics body
        PhysicsBodyData floor = CreatePhysicsBodyRectangle(new Vector2( screenWidth/2, screenHeight ), screenWidth, 100, 10);
        floor.enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
        PhysicsBodyData wall = CreatePhysicsBodyRectangle(new Vector2( screenWidth/2, screenHeight*0.8f ), 10, 80, 10);
        wall.enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)

        // Create left ramp physics body
        PhysicsBodyData rectLeft = CreatePhysicsBodyRectangle(new Vector2( 25, screenHeight - 5 ), 250, 250, 10);
        rectLeft.enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
        SetPhysicsBodyRotation(rectLeft, 30*DEG2RAD);

        // Create right ramp  physics body
        PhysicsBodyData rectRight = CreatePhysicsBodyRectangle(new Vector2( screenWidth - 25, screenHeight - 5 ), 250, 250, 10);
        rectRight.enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
        SetPhysicsBodyRotation(rectRight, 330*DEG2RAD);

        // Create dynamic physics bodies
        PhysicsBodyData bodyA = CreatePhysicsBodyRectangle(new Vector2( 35, screenHeight*0.6f ), 40, 40, 10);
        bodyA.staticFriction = 0.1f;
        bodyA.dynamicFriction = 0.1f;
        SetPhysicsBodyRotation(bodyA, 30*DEG2RAD);

        PhysicsBodyData bodyB = CreatePhysicsBodyRectangle(new Vector2( screenWidth - 35, screenHeight*0.6f ), 40, 40, 10);
        bodyB.staticFriction = 1;
        bodyB.dynamicFriction = 1;
        SetPhysicsBodyRotation(bodyB, 330*DEG2RAD);

        SetTargetFPS(60);
        //--------------------------------------------------------------------------------------

        // Main game loop
        while (!WindowShouldClose())    // Detect window close button or ESC key
        {
            // Update
            //----------------------------------------------------------------------------------
            if (IsKeyPressed('R'))    // Reset physics input
            {
                // Reset dynamic physics bodies position, velocity and rotation
                bodyA.position = new Vector2( 35, screenHeight*0.6f );
                bodyA.velocity = new Vector2( 0, 0 );
                bodyA.angularVelocity = 0;
                SetPhysicsBodyRotation(bodyA, 30*DEG2RAD);

                bodyB.position = new Vector2( screenWidth - 35, screenHeight*0.6f );
                bodyB.velocity = new Vector2( 0, 0 );
                bodyB.angularVelocity = 0;
                SetPhysicsBodyRotation(bodyB, 330*DEG2RAD);
            }
            //----------------------------------------------------------------------------------

            // Draw
            //----------------------------------------------------------------------------------
            BeginDrawing();

                ClearBackground(BLACK);

                DrawFPS(screenWidth - 90, screenHeight - 30);

                // Draw created physics bodies
                int bodiesCount = GetPhysicsBodiesCount();
                for (int i = 0; i < bodiesCount; i++)
                {
                    PhysicsBodyData body = GetPhysicsBody(i);

                    if (body.id != 0) // check for null?
                    {
                        int vertexCount = GetPhysicsShapeVerticesCount(i);
                        for (int j = 0; j < vertexCount; j++)
                        {
                            // Get physics bodies shape vertices to draw lines
                            // Note: GetPhysicsShapeVertex() already calculates rotation transformations
                            Vector2 vertexA = GetPhysicsShapeVertex(body, j);

                            int jj = (((j + 1) < vertexCount) ? (j + 1) : 0);   // Get next vertex or first to close the shape
                            Vector2 vertexB = GetPhysicsShapeVertex(body, jj);

                            DrawLineV(vertexA, vertexB, GREEN);     // Draw a line between two vertex positions
                        }
                    }
                }

                DrawRectangle(0, screenHeight - 49, screenWidth, 49, BLACK);

                DrawText("Friction amount", (screenWidth - MeasureText("Friction amount", 30))/2, 75, 30, WHITE);
                DrawText("0.1", (int)bodyA.position.x - MeasureText("0.1", 20)/2, (int)bodyA.position.y - 7, 20, WHITE);
                DrawText("1", (int)bodyB.position.x - MeasureText("1", 20)/2, (int)bodyB.position.y - 7, 20, WHITE);

                DrawText("Press 'R' to reset example", 10, 10, 10, WHITE);

                DrawText("Physac", logoX, logoY, 30, WHITE);
                DrawText("Powered by", logoX + 50, logoY - 7, 10, WHITE);

            EndDrawing();
            //----------------------------------------------------------------------------------
        }

        // De-Initialization
        //--------------------------------------------------------------------------------------
        ClosePhysics();       // Unitialize physics

        CloseWindow();        // Close window and OpenGL context
        //--------------------------------------------------------------------------------------

        return 0;
    }


}