/*******************************************************************************************
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								*
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								*   raylib [shaders] example - Simple shader mask
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								*
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								*   This example has been created using raylib 2.5 (www.raylib.com)
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								*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
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								*
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								*   Example contributed by Chris Camacho (@codifies -  http://bedroomcoders.co.uk/) 
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								*   and reviewed by Ramon Santamaria (@raysan5)
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								*
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								*   Copyright (c) 2019 Chris Camacho (@codifies) and Ramon Santamaria (@raysan5)
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								*
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								********************************************************************************************
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								*
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								*   The shader makes alpha holes in the forground to give the apearance of a top
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								*   down look at a spotlight casting a pool of light...
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								* 
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								*   The right hand side of the screen there is just enough light to see whats
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								*   going on without the spot light, great for a stealth type game where you
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								*   have to avoid the spotlights.
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								* 
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								*   The left hand side of the screen is in pitch dark except for where the spotlights are.
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								* 
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								*   Although this example doesn't scale like the letterbox example, you could integrate
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								*   the two techniques, but by scaling the actual colour of the render texture rather
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								*   than using alpha as a mask.
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								*
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								********************************************************************************************/
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								#include "raylib.h"
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								#include "raymath.h"
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								#include <stddef.h>
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								#include <stdint.h>
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								#if defined(PLATFORM_DESKTOP)
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								    #define GLSL_VERSION            330
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								#else   // PLATFORM_RPI, PLATFORM_ANDROID, PLATFORM_WEB
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								    #define GLSL_VERSION            100
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								#endif
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								#define MAXSPOT           3	// NB must be the same as define in shader
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								#define numStars        400
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								// Spot data
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								typedef struct {   
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								    Vector2 pos;
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								    Vector2 vel;
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								    float inner;
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								    float radius;
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								    // Shader locations
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								    unsigned int posLoc;
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								    unsigned int innerLoc;
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								    unsigned int radiusLoc;
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								} Spot;
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								// Stars in the star field have a position and velocity
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								typedef struct Star {
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								    Vector2 pos;
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								    Vector2 vel;
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								} Star;
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								void UpdateStar(Star *s);
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								void ResetStar(Star *s);
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								int main(void)
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								{
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								    // Initialization
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								    //--------------------------------------------------------------------------------------
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								    const int screenWidth = 800;
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								    const int screenHeight = 450;
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								    InitWindow(screenWidth, screenHeight, "raylib - shader spotlight");
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								    HideCursor();
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								    Texture texRay = LoadTexture("resources/raysan.png");
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								    Star stars[numStars] = { 0 };
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								    for (int n = 0; n < numStars; n++) ResetStar(&stars[n]);
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								    // Progress all the stars on, so they don't all start in the centre
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								    for (int m = 0; m < screenWidth/2.0; m++) 
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								    {
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								        for (int n = 0; n < numStars; n++) UpdateStar(&stars[n]);
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								    }
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								    int frameCounter = 0;
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								    // Use default vert shader
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								    Shader spotShader = LoadShader(0, FormatText("resources/shaders/glsl%i/spotlight.fs", GLSL_VERSION));
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									// Get the locations of spots in the shader
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									Spot spots[MAXSPOT];
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								/*
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								    unsigned int posLoc;
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								    unsigned int innerLoc;
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								    unsigned int radiusLoc;
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								*/    
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								    for (int i = 0; i < MAXSPOT; i++) 
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								    {
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										char posName[32] = "spots[x].pos\0";
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										char innerName[32] = "spots[x].inner\0";
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										char radiusName[32] = "spots[x].radius\0";
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										posName[6] = '0' + i;
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										innerName[6] = '0' + i;
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										radiusName[6] = '0' + i;
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										spots[i].posLoc = GetShaderLocation(spotShader, posName);
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										spots[i].innerLoc = GetShaderLocation(spotShader, innerName);
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										spots[i].radiusLoc = GetShaderLocation(spotShader, radiusName);
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									}
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									// tell the shader how wide the screen is so we can have
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									// a pitch black half and a dimly lit half.
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									{
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										unsigned int wLoc = GetShaderLocation(spotShader, "screenWidth");
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										float sw = (float)GetScreenWidth();
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										SetShaderValue(spotShader, wLoc, &sw, UNIFORM_FLOAT);
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									}
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								    // randomise the locations and velocities of the spotlights
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								    // and initialise the shader locations
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								    for (int i = 0; i < MAXSPOT; i++)
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								    {
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										spots[i].pos.x = GetRandomValue(64, screenWidth - 64);
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										spots[i].pos.y = GetRandomValue(64, screenHeight - 64);
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										spots[i].vel = (Vector2){ 0, 0 };
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										while ((fabs(spots[i].vel.x) + fabs(spots[i].vel.y)) < 2)
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								        {
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											spots[i].vel.x = GetRandomValue(-40, 40)/10.0;
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											spots[i].vel.y = GetRandomValue(-40, 40)/10.0;
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										}
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										spots[i].inner = 28 * (i + 1);
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										spots[i].radius = 48 * (i + 1);
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										SetShaderValue(spotShader, spots[i].posLoc, &spots[i].pos.x, UNIFORM_VEC2);
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										SetShaderValue(spotShader, spots[i].innerLoc, &spots[i].inner, UNIFORM_FLOAT);
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										SetShaderValue(spotShader, spots[i].radiusLoc, &spots[i].radius, UNIFORM_FLOAT);
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									}
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								    SetTargetFPS(60);               // Set  to run at 60 frames-per-second
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								    //--------------------------------------------------------------------------------------
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								    // Main game loop
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								    while (!WindowShouldClose())    // Detect window close button or ESC key
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								    {
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								        // Update
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								        //----------------------------------------------------------------------------------
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								        frameCounter++;
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										// Move the stars, resetting them if the go offscreen
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								        for (int n = 0; n < numStars; n++) UpdateStar(&stars[n]);
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										// Update the spots, send them to the shader
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										for (int i = 0; i < MAXSPOT; i++)
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								        {
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											if ( i == 0 ) {
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												Vector2 mp = GetMousePosition();
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												spots[i].pos.x = mp.x;					
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												spots[i].pos.y = screenHeight - mp.y;
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											} else {
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												spots[i].pos.x += spots[i].vel.x;					
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												spots[i].pos.y += spots[i].vel.y;
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												if (spots[i].pos.x < 64) spots[i].vel.x = -spots[i].vel.x;					
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												if (spots[i].pos.x > screenWidth - 64) spots[i].vel.x = -spots[i].vel.x;					
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												if (spots[i].pos.y < 64) spots[i].vel.y = -spots[i].vel.y;					
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												if (spots[i].pos.y > screenHeight - 64) spots[i].vel.y = -spots[i].vel.y;
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											}
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											SetShaderValue(spotShader, spots[i].posLoc, &spots[i].pos.x, UNIFORM_VEC2);				
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										}
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								        // Draw
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								        //----------------------------------------------------------------------------------
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								        BeginDrawing();
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								            ClearBackground(DARKBLUE);
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											// Draw stars and bobs
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								            for (int n = 0; n < numStars; n++)
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								            {
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												// Single pixel is just too small these days!
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								                DrawRectangle(stars[n].pos.x, stars[n].pos.y, 2, 2, WHITE);
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								            }
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								            for (int i = 0; i < 16; i++)
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								            {
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								                DrawTexture(texRay,
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								                    (screenWidth/2.0) + cos((frameCounter + i*8)/51.45f)*(screenWidth/2.2) - 32,
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								                    (screenHeight/2.0) + sin((frameCounter + i*8)/17.87f)*(screenHeight/4.2),
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								                    WHITE);
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								            }
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											// Draw spot lights
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											BeginShaderMode(spotShader);
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												// instead of a blank rectangle you could render here
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												// a render texture of the full screen used to do screen
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												// scaling (slight adjustment to shader would be required
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												// to actually pay attention to the colour!)
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												DrawRectangle(0,0,screenWidth,screenHeight,WHITE);
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											EndShaderMode();
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								            DrawFPS(10, 10);
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								            DrawText("Move the mouse!", 10, 30, 20, GREEN);
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								            DrawText("Pitch Black", screenWidth * .2, screenHeight / 2, 20, GREEN);
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								            DrawText("Dark", screenWidth * .66, screenHeight / 2, 20, GREEN);
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								        EndDrawing();
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								        //----------------------------------------------------------------------------------
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								    }
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								    // De-Initialization
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								    //--------------------------------------------------------------------------------------
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								    UnloadTexture(texRay);
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								    CloseWindow();        // Close window and OpenGL context
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								    //--------------------------------------------------------------------------------------
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								    return 0;
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								}
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								void ResetStar(Star *s)
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								{
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								    s->pos = (Vector2){ GetScreenWidth()/2.0f, GetScreenHeight()/2.0f };
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								    do
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								    {
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								        s->vel.x = (float)GetRandomValue(-1000, 1000)/100.0f;
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								        s->vel.y = (float)GetRandomValue(-1000, 1000)/100.0f;
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								    } while (!(fabs(s->vel.x) + fabs(s->vel.y) > 1));
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								    s->pos = Vector2Add(s->pos, Vector2MultiplyV(s->vel, (Vector2){ 8, 8 }));
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								}
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								void UpdateStar(Star *s)
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								{
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								    s->pos = Vector2Add(s->pos, s->vel);
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								    if (s->pos.x < 0 || s->pos.x > GetScreenWidth() ||
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								        s->pos.y < 0 || s->pos.y > GetScreenHeight())
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								    {
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								        ResetStar(s);
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								    }
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								}
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