/*******************************************************************************************
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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 (@chriscamacho -  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 (@chriscamacho) 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 MAX_SPOTS         3        // NOTE: It must be the same as define in shader
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								#define MAX_STARS       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[MAX_STARS] = { 0 };
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								    for (int n = 0; n < MAX_STARS; 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 < MAX_STARS; 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 shdrSpot = LoadShader(0, TextFormat("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[MAX_SPOTS];
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								    for (int i = 0; i < MAX_SPOTS; 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(shdrSpot, posName);
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								        spots[i].innerLoc = GetShaderLocation(shdrSpot, innerName);
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								        spots[i].radiusLoc = GetShaderLocation(shdrSpot, 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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								    unsigned int wLoc = GetShaderLocation(shdrSpot, "screenWidth");
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								    float sw = (float)GetScreenWidth();
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								    SetShaderValue(shdrSpot, wLoc, &sw, SHADER_UNIFORM_FLOAT);
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								    // Randomize the locations and velocities of the spotlights
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								    // and initialize the shader locations
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								    for (int i = 0; i < MAX_SPOTS; i++)
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								    {
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								        spots[i].pos.x = (float)GetRandomValue(64, screenWidth - 64);
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								        spots[i].pos.y = (float)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(-400, 40) / 10.0f;
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								            spots[i].vel.y = GetRandomValue(-400, 40) / 10.0f;
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								        }
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								        spots[i].inner = 28.0f * (i + 1);
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								        spots[i].radius = 48.0f * (i + 1);
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								        SetShaderValue(shdrSpot, spots[i].posLoc, &spots[i].pos.x, SHADER_UNIFORM_VEC2);
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								        SetShaderValue(shdrSpot, spots[i].innerLoc, &spots[i].inner, SHADER_UNIFORM_FLOAT);
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								        SetShaderValue(shdrSpot, spots[i].radiusLoc, &spots[i].radius, SHADER_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 < MAX_STARS; 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 < MAX_SPOTS; i++)
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								        {
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								            if (i == 0)
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								            {
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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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								            }
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								            else
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								            {
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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(shdrSpot, spots[i].posLoc, &spots[i].pos.x, SHADER_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 < MAX_STARS; n++)
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								            {
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								                // Single pixel is just too small these days!
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								                DrawRectangle((int)stars[n].pos.x, (int)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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								                    (int)((screenWidth/2.0f) + cos((frameCounter + i*8)/51.45f)*(screenWidth/2.2f) - 32),
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								                    (int)((screenHeight/2.0f) + sin((frameCounter + i*8)/17.87f)*(screenHeight/4.2f)), WHITE);
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								            }
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								            // Draw spot lights
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								            BeginShaderMode(shdrSpot);
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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", (int)(screenWidth*0.2f), screenHeight/2, 20, GREEN);
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								            DrawText("Dark", (int)(screenWidth*.66f), 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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								    UnloadShader(shdrSpot);
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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, Vector2Multiply(s->vel, (Vector2){ 8.0f, 8.0f }));
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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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