/*******************************************************************************************
*
*   raylib [textures] example - Background scrolling
*
*   This example has been created using raylib 2.0 (www.raylib.com)
*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
*
*   Copyright (c) 2019 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

#include "raylib.h"

#if defined(PLATFORM_WEB)
    #include <emscripten/emscripten.h>
#endif

//----------------------------------------------------------------------------------
// Global Variables Definition
//----------------------------------------------------------------------------------
const int screenWidth = 800;
const int screenHeight = 450;

// NOTE: Textures MUST be loaded after Window initialization (OpenGL context is required)

Texture2D background = { 0 };
Texture2D midground = { 0 };
Texture2D foreground = { 0 };

float scrollingBack = 0;
float scrollingMid = 0;
float scrollingFore = 0;

//----------------------------------------------------------------------------------
// Module Functions Declaration
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void);     // Update and Draw one frame

//----------------------------------------------------------------------------------
// Program Main Entry Point
//----------------------------------------------------------------------------------
int main(void)
{
    // Initialization
    //--------------------------------------------------------------------------------------
    InitWindow(screenWidth, screenHeight, "raylib [textures] example - background scrolling");

    // NOTE: Be careful, background width must be equal or bigger than screen width
    // if not, texture should be draw more than two times for scrolling effect
    background = LoadTexture("resources/cyberpunk_street_background.png");
    midground = LoadTexture("resources/cyberpunk_street_midground.png");
    foreground = LoadTexture("resources/cyberpunk_street_foreground.png");

#if defined(PLATFORM_WEB)
    emscripten_set_main_loop(UpdateDrawFrame, 0, 1);
#else
    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
    //--------------------------------------------------------------------------------------

    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        UpdateDrawFrame();
    }
#endif

    // De-Initialization
    //--------------------------------------------------------------------------------------
    UnloadTexture(background);  // Unload background texture
    UnloadTexture(midground);   // Unload midground texture
    UnloadTexture(foreground);  // Unload foreground texture

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

    return 0;
}

//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void)
{
    // Update
    //----------------------------------------------------------------------------------
    scrollingBack -= 0.1f;
    scrollingMid -= 0.5f;
    scrollingFore -= 1.0f;

    // NOTE: Texture is scaled twice its size, so it sould be considered on scrolling
    if (scrollingBack <= -background.width*2) scrollingBack = 0;
    if (scrollingMid <= -midground.width*2) scrollingMid = 0;
    if (scrollingFore <= -foreground.width*2) scrollingFore = 0;
    //----------------------------------------------------------------------------------

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

        ClearBackground(GetColor(0x052c46ff));

        // Draw background image twice
        // NOTE: Texture is scaled twice its size
        DrawTextureEx(background, (Vector2){ scrollingBack, 20 }, 0.0f, 2.0f, WHITE);
        DrawTextureEx(background, (Vector2){ background.width*2 + scrollingBack, 20 }, 0.0f, 2.0f, WHITE);

        // Draw midground image twice
        DrawTextureEx(midground, (Vector2){ scrollingMid, 20 }, 0.0f, 2.0f, WHITE);
        DrawTextureEx(midground, (Vector2){ midground.width*2 + scrollingMid, 20 }, 0.0f, 2.0f, WHITE);

        // Draw foreground image twice
        DrawTextureEx(foreground, (Vector2){ scrollingFore, 70 }, 0.0f, 2.0f, WHITE);
        DrawTextureEx(foreground, (Vector2){ foreground.width*2 + scrollingFore, 70 }, 0.0f, 2.0f, WHITE);

        DrawText("BACKGROUND SCROLLING & PARALLAX", 10, 10, 20, RED);
        DrawText("(c) Cyberpunk Street Environment by Luis Zuno (@ansimuz)", screenWidth - 330, screenHeight - 20, 10, RAYWHITE);

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