becs/examples/example1/example1.c

#define BECS_MAX_ENTITIES 100000ULL
#define BECS_MAX_COMPONENTS 4ULL
#define BECS_IMPLEMENTATION
#include "../../becs.h"
#include <stdlib.h>
#include <stdio.h>
#include "external/raylib/src/raylib.h"
#include "external/raylib/src/rlgl.h"
#include "external/raylib/src/raymath.h"

// Component structs
typedef struct {
    float x, y;
} Position;

typedef struct {
    float vx, vy;
} Velocity;

typedef struct {
    float ax, ay;
} Acceleration;

typedef struct {
    float radius;
    float lifetime;
} ParticleData;

// Function to spawn a particle
void SpawnParticle(BECS_ECS *ecs, BECS_ComponentID posID, BECS_ComponentID velID, BECS_ComponentID accID, BECS_ComponentID dataID, float x, float y) {
    BECS_Entity entity = BECS_EntityCreate(ecs);
    if (entity == BECS_NULL_ENTITY) return;

    Position *pos = (Position *)BECS_ComponentAdd(ecs, entity, posID);
    pos->x = x;
    pos->y = y;

    Velocity *vel = (Velocity *)BECS_ComponentAdd(ecs, entity, velID);
    vel->vx = GetRandomValue(-100, 100);
    vel->vy = GetRandomValue(-200, -50);

    Acceleration *acc = (Acceleration *)BECS_ComponentAdd(ecs, entity, accID);
    acc->ax = 0.0f;
    acc->ay = 100.0f; // Gravity

    ParticleData *data = (ParticleData *)BECS_ComponentAdd(ecs, entity, dataID);
    data->radius = 5.0f;
    data->lifetime = 2.0f;
}

void LifetimeSystem(BECS_ECS *ecs, float dt, ParticleData *data, BECS_Entity *entity) {
    // ParticleData *data = (ParticleData *)ecs->componentPools[3].denseArray;
    // BECS_Entity *entity = (BECS_Entity *)ecs->componentPools[3].denseEntityMapping;
    // for (uint32_t i = 0; i < ecs->entityCount; i++) {
    uint32_t entityCount = ecs->entityCount;
    for (uint32_t i = 0; i < entityCount; i++) {
        data[i].lifetime -= dt;
        if (data[i].lifetime <= 0.0f) {
            BECS_EntityDestroy(ecs, entity[i]);
        }
    }
}

void PhysicsSystem(BECS_ECS *ecs, float dt, Position *pos, Velocity *vel, Acceleration *acc) {
    //Position *pos = ((Position *)ecs->componentPools[0].denseArray);
    //Velocity *vel = ((Velocity *)ecs->componentPools[1].denseArray);
    // Acceleration *acc = ((Acceleration *)ecs->componentPools[2].denseArray);
    // for (uint32_t i = 0; i < ecs->entityCount; i++) {
    uint32_t entityCount = ecs->entityCount;
    for (uint32_t i = 0; i < entityCount; i++) {
        vel[i].vy += acc[i].ay * dt;
        vel[i].vx += acc[i].ax * dt;
        pos[i].y += vel[i].vy * dt;
        pos[i].x += vel[i].vx * dt;
    }
}

void RenderSystem(BECS_ECS *ecs, float dt, Position *pos, ParticleData *data) {
    // Position *pos = ((Position *)ecs->componentPools[0].denseArray);
    // ParticleData *data = ((ParticleData *)ecs->componentPools[3].denseArray);
    // for (uint32_t i = 0; i < ecs->entityCount; i++) {
    uint32_t entityCount = ecs->entityCount;
    for (uint32_t i = 0; i < entityCount; i++) {
        float alpha = data[i].lifetime / 2.0;
        Color color = {255, 255, 255, (unsigned char)(alpha * 255)};
        DrawCircle(pos[i].x, pos[i].y, data[i].radius, color);
    }
}

// NOTE: This didn't actually improve it as much as I wanted. Gotta look for a better way to render.
void DrawCircleBatched(Vector2 *positions, float *radii, Color *colors, uint32_t count, uint32_t segments) {
    rlBegin(RL_TRIANGLES);
    for(uint32_t i=0 ;i<count; i++){
        Vector2 center=positions[i];
        float radius=radii[i];
        Color color=colors[i];
        rlColor4ub(color.r,color.g,color.b,color.a);

        //Approximatecirclewithtriangles
        for(uint32_t j=0; j<segments; j++){
            float angle1=(j*2.0f*PI)/segments;
            float angle2=((j+1)*2.0f*PI)/segments;

            Vector2 v1={center.x+radius*cosf(angle1),center.y+radius*sinf(angle1)};
            Vector2 v2={center.x+radius*cosf(angle2),center.y+radius*sinf(angle2)};

            rlVertex2f(center.x,center.y);
            rlVertex2f(v1.x,v1.y);
            rlVertex2f(v2.x,v2.y);
        }
    }
    rlEnd();
}

void RenderSystemBatched(BECS_ECS *ecs, float dt, Position *pos, ParticleData *data, Vector2 *posArray, float *radArray, Color *colArray) {
    uint32_t batchCount = 0;
    uint32_t entityCount = ecs->componentPools[0].count;//Use correct count
    for(uint32_t i=0; i<entityCount; i++){
        posArray[batchCount]=(Vector2){pos[i].x,pos[i].y};
        radArray[batchCount]=data[i].radius;
        float alpha=data[i].lifetime/2.0f;
        colArray[batchCount]=(Color){255,255,255,(unsigned char)(alpha*255)};
        batchCount++;
    }
    DrawCircleBatched(posArray, radArray, colArray, batchCount, 16);
}

int main(void) {
    // Initialize ECS
    size_t componentSizes[4] = {sizeof(Position), sizeof(Velocity), sizeof(Acceleration), sizeof(ParticleData)};
    size_t memSize = BECS_GetMinMemoryArenaSize(componentSizes, 4);
#ifdef _WIN32
    printf("%llu\n", memSize);
#elif __unix__
    printf("%lu\n", memSize);
#endif
    char *memory = (char *)malloc(memSize);
    BECS_ECS ecs = BECS_InitECS(memory, memSize);

    // Register components
    BECS_ComponentID posID = BECS_ComponentRegister(&ecs, sizeof(Position), BECS_MAX_ENTITIES);
    BECS_ComponentID velID = BECS_ComponentRegister(&ecs, sizeof(Velocity), BECS_MAX_ENTITIES);
    BECS_ComponentID accID = BECS_ComponentRegister(&ecs, sizeof(Acceleration), BECS_MAX_ENTITIES);
    BECS_ComponentID dataID = BECS_ComponentRegister(&ecs, sizeof(ParticleData), BECS_MAX_ENTITIES);

    Position *posData = (Position *)BECS_ComponentGetPool(&ecs, posID);
    Velocity *velData = (Velocity *)BECS_ComponentGetPool(&ecs, velID);
    Acceleration *accData = (Acceleration *)BECS_ComponentGetPool(&ecs, accID);
    ParticleData *dataData = (ParticleData *)BECS_ComponentGetPool(&ecs, dataID);

    // TODO: This should probably be done in a query system
    BECS_Entity *entityData = (BECS_Entity *)ecs.componentPools[dataID].denseEntityMapping;

    InitWindow(1600, 800, "2D Particle System with BECS");

    Vector2 *posArray = malloc(BECS_MAX_ENTITIES * sizeof(Vector2));
    float *radArray = malloc(BECS_MAX_ENTITIES * sizeof(float));
    Color *colArray = malloc(BECS_MAX_ENTITIES * sizeof(Color));

    rlMatrixMode(RL_PROJECTION);
    rlLoadIdentity();
    rlOrtho(0,GetScreenWidth(),GetScreenHeight(),0, 0.0f, 1.0f);
    rlMatrixMode(RL_MODELVIEW);
    rlLoadIdentity();
    rlSetBlendMode(RL_BLEND_ALPHA);
    rlDisableBackfaceCulling();
    rlDisableDepthTest();
    rlDisableTexture();
    rlDrawRenderBatchActive();

    while (!WindowShouldClose()) {
        float dt = GetFrameTime();

        LifetimeSystem(&ecs, dt, dataData, entityData);

        // Spawn particle on mouse click
        if (IsMouseButtonDown(MOUSE_LEFT_BUTTON)) {
            Vector2 mousePos = GetMousePosition();
            for (uint32_t i = 0; i < 100; i++) {
                SpawnParticle(&ecs, posID, velID, accID, dataID, mousePos.x, mousePos.y);
            }
        }

        PhysicsSystem(&ecs, dt, posData, velData, accData);

        BeginDrawing();
            ClearBackground(BLACK);

            // RenderSystem(&ecs, dt, posData, dataData);
            RenderSystemBatched(&ecs, dt, posData, dataData, posArray, radArray, colArray);

            DrawText(TextFormat("Particles: %u", ecs.entityCount), 10, 10, 20, WHITE);
            DrawText(TextFormat("Time(ms): %f", dt * 1000), 10, 30, 20, WHITE);
            DrawText(TextFormat("FPS: %f", 1/dt), 10, 50, 20, WHITE);
            DrawText(TextFormat("Screen Res: %d x %d", GetScreenWidth(), GetScreenHeight()), 10, 70, 20, WHITE);
        EndDrawing();
    }

    CloseWindow();
    free(memory);
    free(posArray);
    free(colArray);
    free(radArray);
    return 0;
}