/*******************************************************************************************
*
*   raylib [shaders] example - multi sample2d
*
*   Example complexity rating: [★★☆☆] 2/4
*
*   NOTE: This example requires raylib OpenGL 3.3 or ES2 versions for shaders support,
*         OpenGL 1.1 does not support shaders, recompile raylib to OpenGL 3.3 version
*
*   NOTE: Shaders used in this example are #version 330 (OpenGL 3.3), to test this example
*         on OpenGL ES 2.0 platforms (Android, Raspberry Pi, HTML5), use #version 100 shaders
*         raylib comes with shaders ready for both versions, check raylib/shaders install folder
*
*   Example originally created with raylib 3.5, last time updated with raylib 3.5
*
*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
*   BSD-like license that allows static linking with closed source software
*
*   Copyright (c) 2020-2025 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

using static Raylib_cs.Raylib;

namespace Examples.Shaders;

public class MultiSample2d : IExample
{
    private const int screenWidth = 800;
    private const int screenHeight = 450;

#if BROWSER
    const int GlslVersion = 100;    // WebGL1 needs GLSL ES 100
#else
    private const int GlslVersion = 330;
#endif

    public string Name => "Shaders / Multi Sample 2D";

    public string Title => "raylib [shaders] example - multi sample2d";

    private Texture2D texRed;
    private Texture2D texBlue;
    private Shader shader;
    private int texBlueLoc;
    private int dividerLoc;
    private float dividerValue;

    public void Init()
    {
        var imRed = GenImageColor(800, 450, new Color(255, 0, 0, 255));
        texRed = LoadTextureFromImage(imRed);
        UnloadImage(imRed);

        var imBlue = GenImageColor(800, 450, new Color(0, 0, 255, 255));
        texBlue = LoadTextureFromImage(imBlue);
        UnloadImage(imBlue);

        shader = LoadShader(null, $"resources/shaders/glsl{GlslVersion}/color_mix.fs");

        // Get an additional sampler2D location to be enabled on drawing
        texBlueLoc = GetShaderLocation(shader, "texture1");

        // Get shader uniform for divider
        dividerLoc = GetShaderLocation(shader, "divider");
        dividerValue = 0.5f;
    }

    public void Update()
    {
        // Update
        //----------------------------------------------------------------------------------
        if (IsKeyDown(KeyboardKey.Right))
        {
            dividerValue += 0.01f;
        }
        else if (IsKeyDown(KeyboardKey.Left))
        {
            dividerValue -= 0.01f;
        }

        if (dividerValue < 0.0f)
        {
            dividerValue = 0.0f;
        }
        else if (dividerValue > 1.0f)
        {
            dividerValue = 1.0f;
        }

        Raylib.SetShaderValue(shader, dividerLoc, dividerValue, ShaderUniformDataType.Float);
        //----------------------------------------------------------------------------------

        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();
        ClearBackground(Color.RayWhite);

        BeginShaderMode(shader);

        // WARNING: Additional textures (sampler2D) are enabled for ALL draw calls in the batch,
        // but EndShaderMode() forces batch drawing and resets active textures, this way
        // other textures (sampler2D) can be activated on consequent drawings (if required)
        // The downside of this approach is that SetShaderValue() must be called inside the loop,
        // to be set again after every EndShaderMode() reset
        SetShaderValueTexture(shader, texBlueLoc, texBlue);

        // We are drawing texRed using default [sampler2D texture0] but
        // an additional texture units is enabled for texBlue [sampler2D texture1]
        DrawTexture(texRed, 0, 0, Color.White);

        EndShaderMode(); // Texture sampler2D is reseted, needs to be set again for next frame

        var y = GetScreenHeight() - 40;
        DrawText("Use KEY_LEFT/KEY_RIGHT to move texture mixing in shader!", 80, y, 20, Color.RayWhite);

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

    public void Unload()
    {
        UnloadShader(shader);
        UnloadTexture(texRed);
        UnloadTexture(texBlue);
    }

    public static int Main()
    {
        // Initialization
        //--------------------------------------------------------------------------------------
        InitWindow(screenWidth, screenHeight, "raylib [shaders] example - multi sample2d");

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

        var game = new MultiSample2d();
        game.Init();

        // Main game loop
        while (!WindowShouldClose())
        {
            game.Update();
        }

        game.Unload();

        // De-Initialization
        //--------------------------------------------------------------------------------------
        CloseWindow();
        //--------------------------------------------------------------------------------------

        return 0;
    }
}