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								/*******************************************************************************************

								*

								*   raylib [shaders] example - OpenGL point particle system

								*

								*   Example originally created with raylib 3.8, last time updated with raylib 2.5

								*

								*   Example contributed by Stephan Soller (@arkanis) and reviewed by Ramon Santamaria (@raysan5)

								*

								*   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) 2021-2024 Stephan Soller (@arkanis) and Ramon Santamaria (@raysan5)

								*

								********************************************************************************************

								*

								*   Mixes raylib and plain OpenGL code to draw a GL_POINTS based particle system. The

								*   primary point is to demonstrate raylib and OpenGL interop.

								*

								*   rlgl batched draw operations internally so we have to flush the current batch before

								*   doing our own OpenGL work (rlDrawRenderBatchActive()).

								*

								*   The example also demonstrates how to get the current model view projection matrix of

								*   raylib. That way raylib cameras and so on work as expected.

								*

								********************************************************************************************/


								#include "raylib.h"


								#if defined(PLATFORM_DESKTOP) || defined(PLATFORM_DESKTOP_SDL)

								    #if defined(GRAPHICS_API_OPENGL_ES2)

								        #include "glad_gles2.h"       // Required for: OpenGL functionality

								        #define glGenVertexArrays glGenVertexArraysOES

								        #define glBindVertexArray glBindVertexArrayOES

								        #define glDeleteVertexArrays glDeleteVertexArraysOES

								        #define GLSL_VERSION            100

								    #else

								        #if defined(__APPLE__)

								            #define GL_SILENCE_DEPRECATION // Silence Opengl API deprecation warnings

								            #include <OpenGL/gl3.h>     // OpenGL 3 library for OSX

								            #include <OpenGL/gl3ext.h>  // OpenGL 3 extensions library for OSX

								        #else

								            #include "glad.h"       // Required for: OpenGL functionality

								        #endif

								        #define GLSL_VERSION            330

								    #endif

								#else   // PLATFORM_ANDROID, PLATFORM_WEB

								    #define GLSL_VERSION            100

								#endif


								#include "rlgl.h"           // Required for: rlDrawRenderBatchActive(), rlGetMatrixModelview(), rlGetMatrixProjection()

								#include "raymath.h"        // Required for: MatrixMultiply(), MatrixToFloat()


								#define MAX_PARTICLES       1000


								// Particle type

								typedef struct Particle {

								    float x;

								    float y;

								    float period;

								} Particle;


								//------------------------------------------------------------------------------------

								// Program main entry point

								//------------------------------------------------------------------------------------

								int main(void)

								{

								    // Initialization

								    //--------------------------------------------------------------------------------------

								    const int screenWidth = 800;

								    const int screenHeight = 450;


								    InitWindow(screenWidth, screenHeight, "raylib - point particles");


								    Shader shader = LoadShader(TextFormat("resources/shaders/glsl%i/point_particle.vs", GLSL_VERSION),

								                               TextFormat("resources/shaders/glsl%i/point_particle.fs", GLSL_VERSION));


								    int currentTimeLoc = GetShaderLocation(shader, "currentTime");

								    int colorLoc = GetShaderLocation(shader, "color");


								    // Initialize the vertex buffer for the particles and assign each particle random values

								    Particle particles[MAX_PARTICLES] = { 0 };


								    for (int i = 0; i < MAX_PARTICLES; i++)

								    {

								        particles[i].x = (float)GetRandomValue(20, screenWidth - 20);

								        particles[i].y = (float)GetRandomValue(50, screenHeight - 20);


								        // Give each particle a slightly different period. But don't spread it to much.

								        // This way the particles line up every so often and you get a glimps of what is going on.

								        particles[i].period = (float)GetRandomValue(10, 30)/10.0f;

								    }


								    // Create a plain OpenGL vertex buffer with the data and an vertex array object

								    // that feeds the data from the buffer into the vertexPosition shader attribute.

								    GLuint vao = 0;

								    GLuint vbo = 0;

								    glGenVertexArrays(1, &vao);

								    glBindVertexArray(vao);

								        glGenBuffers(1, &vbo);

								        glBindBuffer(GL_ARRAY_BUFFER, vbo);

								        glBufferData(GL_ARRAY_BUFFER, MAX_PARTICLES*sizeof(Particle), particles, GL_STATIC_DRAW);

								        // Note: LoadShader() automatically fetches the attribute index of "vertexPosition" and saves it in shader.locs[SHADER_LOC_VERTEX_POSITION]

								        glVertexAttribPointer(shader.locs[SHADER_LOC_VERTEX_POSITION], 3, GL_FLOAT, GL_FALSE, 0, 0);

								        glEnableVertexAttribArray(0);

								        glBindBuffer(GL_ARRAY_BUFFER, 0);

								    glBindVertexArray(0);


								    // Allows the vertex shader to set the point size of each particle individually

								    #ifndef GRAPHICS_API_OPENGL_ES2

								    glEnable(GL_PROGRAM_POINT_SIZE);

								    #endif


								    SetTargetFPS(60);

								    //--------------------------------------------------------------------------------------


								    // Main game loop

								    while (!WindowShouldClose())    // Detect window close button or ESC key

								    {

								        // Draw

								        //----------------------------------------------------------------------------------

								        BeginDrawing();

								            ClearBackground(WHITE);


								            DrawRectangle(10, 10, 210, 30, MAROON);

								            DrawText(TextFormat("%zu particles in one vertex buffer", MAX_PARTICLES), 20, 20, 10, RAYWHITE);


								            rlDrawRenderBatchActive();      // Draw iternal buffers data (previous draw calls)


								            // Switch to plain OpenGL

								            //------------------------------------------------------------------------------

								            glUseProgram(shader.id);


								                glUniform1f(currentTimeLoc, GetTime());


								                Vector4 color = ColorNormalize((Color){ 255, 0, 0, 128 });

								                glUniform4fv(colorLoc, 1, (float *)&color);


								                // Get the current modelview and projection matrix so the particle system is displayed and transformed

								                Matrix modelViewProjection = MatrixMultiply(rlGetMatrixModelview(), rlGetMatrixProjection());


								                glUniformMatrix4fv(shader.locs[SHADER_LOC_MATRIX_MVP], 1, false, MatrixToFloat(modelViewProjection));


								                glBindVertexArray(vao);

								                    glDrawArrays(GL_POINTS, 0, MAX_PARTICLES);

								                glBindVertexArray(0);


								            glUseProgram(0);

								            //------------------------------------------------------------------------------


								            DrawFPS(screenWidth - 100, 10);


								        EndDrawing();

								        //----------------------------------------------------------------------------------

								    }


								    // De-Initialization

								    //--------------------------------------------------------------------------------------

								    glDeleteBuffers(1, &vbo);

								    glDeleteVertexArrays(1, &vao);


								    UnloadShader(shader);   // Unload shader


								    CloseWindow();          // Close window and OpenGL context

								    //--------------------------------------------------------------------------------------


								    return 0;

								}