[Examples] Added shapes_particles

examples/shapes/shapes_particles.c

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+/*******************************************************************************************
+*
+*   raylib [shapes] example - particles
+*
+*   Example complexity rating: [★☆☆☆] 1/4
+*
+*   Example originally created with raylib 5.6, last time updated with raylib 5.6
+*
+*   Example contributed by Jordi Santonja (@JordSant)
+*
+*   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) 2025 Jordi Santonja (@JordSant)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#include <stdlib.h>         // Required for: calloc(), free()
+#include <math.h>           // Required for: cosf(), sinf()
+
+#define MAX_PARTICLES 300   // Max number particles
+
+//----------------------------------------------------------------------------------
+// Types and Structures Definition
+//----------------------------------------------------------------------------------
+typedef enum ParticleType {
+    WATER = 0,
+    SMOKE,
+    FIRE
+} ParticleType;
+
+static const char particleTypesChar[3][10] = { "WATER", "SMOKE", "FIRE" };
+
+typedef struct Particle {
+    Vector2 position;       // Particle position on screen
+	Vector2 velocity;       // Particle current speed and direction
+	bool alive;             // Particle alive: inside screen and life time
+	float lifeTime;         // Particle life time
+	ParticleType type;      // Particle type (WATER, SMOKE, FIRE)
+    float radius;           // Particle radius
+    Color color;            // Particle color
+} Particle;
+
+typedef struct CircularBuffer {
+	int head;               // Index for the next write
+	int tail;               // Index for the next read
+	Particle* buffer;       // Particle buffer array
+} CircularBuffer;
+
+//----------------------------------------------------------------------------------
+// Module Functions Declaration
+//----------------------------------------------------------------------------------
+static Particle* AddToCircularBuffer(CircularBuffer* circularBuffer);
+static void UpdateParticles(CircularBuffer* circularBuffer, int screenWidth, int screenHeight);
+static void UpdateCircularBuffer(CircularBuffer* circularBuffer);
+static void DrawParticles(CircularBuffer* circularBuffer);
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - particles");
+
+    // Definition of particles
+    Particle* particles = (Particle*)RL_CALLOC(MAX_PARTICLES, sizeof(Particle)); // Particle array
+	CircularBuffer circularBuffer = { 0, 0, particles };
+    
+	// Particle emitter parameters
+    int emissionRate = 2;
+	ParticleType currentType = WATER;
+	Vector2 emitterPosition = { screenWidth / 2.0f, screenHeight / 2.0f };
+
+    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+		// Emit new particles: when emissionRate is 1, emit every frame
+        if ((rand() % emissionRate) == 0)
+        {
+            Particle* newParticle = AddToCircularBuffer(&circularBuffer);
+			// If buffer is full, newParticle is NULL
+            if (newParticle != NULL)
+            {
+				// Fill particle properties
+                newParticle->position = emitterPosition;
+                newParticle->alive = true;
+                newParticle->lifeTime = 0.0f;
+				newParticle->type = currentType;
+                float speed = (float)(rand() % 10) / 5.0f;
+                switch (currentType)
+                {
+                    case WATER:
+                        newParticle->radius = 5.0f;
+                        newParticle->color = BLUE;
+                        break;
+                    case SMOKE:
+                        newParticle->radius = 7.0f;
+                        newParticle->color = GRAY;
+                        break;
+                    case FIRE:
+                        newParticle->radius = 10.0f;
+                        newParticle->color = YELLOW;
+                        speed /= 10.0f;
+                        break;
+                    default:
+                        newParticle->radius = 5.0f;
+                        newParticle->color = WHITE;
+                        break;
+				}
+                float direction = (float)(rand() % 360);
+                newParticle->velocity = (Vector2){ speed * cosf(direction * DEG2RAD), speed * sinf(direction * DEG2RAD) };
+            }
+        }
+
+		// Update the parameters of each particle
+        UpdateParticles(&circularBuffer, screenWidth, screenHeight);
+        // Remove dead particles from the circular buffer
+        UpdateCircularBuffer(&circularBuffer);
+
+        // Change Particle Emission Rate (UP/DOWN arrows)
+        if (IsKeyPressed(KEY_UP) && (emissionRate > 1))
+            --emissionRate;
+        if (IsKeyPressed(KEY_DOWN))
+            ++emissionRate;
+
+        // Change Particle Type (LEFT/RIGHT arrows)
+        if (IsKeyPressed(KEY_RIGHT))
+            (currentType == FIRE) ? currentType = WATER : ++currentType;
+        if (IsKeyPressed(KEY_LEFT))
+            (currentType == WATER) ? currentType = FIRE : --currentType;
+
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+        ClearBackground(RAYWHITE);
+
+		// Call the function with a loop to draw all particles
+        DrawParticles(&circularBuffer);
+
+        // Draw UI and Instructions
+        DrawRectangle(5, 5, 315, 75, Fade(SKYBLUE, 0.5f));
+        DrawRectangleLines(5, 5, 315, 75, BLUE);
+
+        DrawText("CONTROLS:", 15, 15, 10, BLACK);
+        DrawText("UP/DOWN: Change Particle Emission Rate", 15, 35, 10, BLACK);
+        DrawText("LEFT/RIGHT: Change Particle Type (Water, Smoke, Fire)", 15, 55, 10, BLACK);
+
+        DrawText(TextFormat("Emission Rate: %d | Type: %s", emissionRate, particleTypesChar[currentType]), 15, 95, 10, DARKGRAY);
+
+        DrawFPS(screenWidth - 80, 10);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    RL_FREE(particles);     // Free particles array data
+
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}
+
+//----------------------------------------------------------------------------------
+// Module Functions Definition
+//----------------------------------------------------------------------------------
+static Particle* AddToCircularBuffer(CircularBuffer* circularBuffer)
+{
+    Particle* particle = NULL;
+
+    // Check if buffer full
+    if (((circularBuffer->head + 1) % MAX_PARTICLES) != circularBuffer->tail)
+    {
+		// Add new particle to the head position and advance head
+        particle = &circularBuffer->buffer[circularBuffer->head];
+        circularBuffer->head = (circularBuffer->head + 1) % MAX_PARTICLES;
+    }
+
+	return particle;
+}
+
+static void UpdateParticles(CircularBuffer* circularBuffer, int screenWidth, int screenHeight)
+{
+    for (int i = circularBuffer->tail; i != circularBuffer->head; i = (i + 1) % MAX_PARTICLES)
+    {
+        // Update particle life and positions
+		circularBuffer->buffer[i].lifeTime += 1.0f / 60.0f; // 60 FPS -> 1/60 seconds per frame
+
+        switch (circularBuffer->buffer[i].type)
+        {
+            case WATER:
+                circularBuffer->buffer[i].position.x += circularBuffer->buffer[i].velocity.x;
+                circularBuffer->buffer[i].velocity.y += 0.2f;   // Gravity
+                circularBuffer->buffer[i].position.y += circularBuffer->buffer[i].velocity.y;
+                break;
+            case SMOKE:
+                circularBuffer->buffer[i].position.x += circularBuffer->buffer[i].velocity.x;
+				circularBuffer->buffer[i].velocity.y -= 0.05f;  // Upwards
+                circularBuffer->buffer[i].position.y += circularBuffer->buffer[i].velocity.y;
+                circularBuffer->buffer[i].radius += 0.5f;       // Increment radius: smoke expands
+				circularBuffer->buffer[i].color.a -= 4;         // Decrement alpha: smoke fades
+				if (circularBuffer->buffer[i].color.a < 4)      // If alpha transparent, particle dies
+                    circularBuffer->buffer[i].alive = false;
+                break;
+            case FIRE:
+				// Add a little horizontal oscillation to fire particles
+                circularBuffer->buffer[i].position.x += circularBuffer->buffer[i].velocity.x + cosf(circularBuffer->buffer[i].lifeTime * 10.0f);
+                circularBuffer->buffer[i].velocity.y -= 0.005f; // Upwards
+                circularBuffer->buffer[i].position.y += circularBuffer->buffer[i].velocity.y;
+				circularBuffer->buffer[i].radius -= 0.05f;      // Decrement radius: fire shrinks
+				circularBuffer->buffer[i].color.g -= 1;         // Decrement green: fire turns reddish starting from yellow
+				if (circularBuffer->buffer[i].radius <= 0.02f)  // If radius too small, particle dies
+                    circularBuffer->buffer[i].alive = false;
+                break;
+            default: break;
+        }
+
+		// Disable particle when out of screen
+        if ((circularBuffer->buffer[i].position.x < 0) ||
+            (circularBuffer->buffer[i].position.x > screenWidth) ||
+            (circularBuffer->buffer[i].position.y < 0) ||
+            (circularBuffer->buffer[i].position.y > screenHeight))
+            circularBuffer->buffer[i].alive = false;
+    }
+}
+static void UpdateCircularBuffer(CircularBuffer* circularBuffer)
+{
+    // Update circular buffer: advance tail over dead particles
+    while ((circularBuffer->tail != circularBuffer->head) &&
+           !circularBuffer->buffer[circularBuffer->tail].alive)
+    {
+        circularBuffer->tail = (circularBuffer->tail + 1) % MAX_PARTICLES;
+	}
+}
+
+static void DrawParticles(CircularBuffer* circularBuffer)
+{
+    for (int i = circularBuffer->tail; i != circularBuffer->head; i = (i + 1) % MAX_PARTICLES)
+    {
+        if (circularBuffer->buffer[i].alive)
+        {
+            DrawCircleV(circularBuffer->buffer[i].position,
+                        circularBuffer->buffer[i].radius,
+                        circularBuffer->buffer[i].color);
+        }
+    }
+}