main.c

#include "raylib.h"

#define WIDTH 800
#define HEIGHT 600
#define AIR 0
#define SAND 1
#define WALL 2

void MouseInput(int rows, int cols, int grid[rows][cols], int w, int mouseSelect){
    int mouseCol = GetMouseX() / w;
    int mouseRow = GetMouseY() / w;

    if(IsMouseButtonDown(MOUSE_LEFT_BUTTON)){
        //Create stuff
        int matrix = 5;
        int extend = matrix / 2;
        for(int i = -extend; i <= extend; i++){
            for(int j = -extend; j <= extend; j++){
                //Get a random value just for the sand to be random and not a block
                if(GetRandomValue(1, 2) == 2 && mouseSelect == SAND){
                    int col = mouseCol + i;
                    int row = mouseRow + j;
                    if(row >= 0 && row < rows && col >= 0 && col < cols){
                         grid[row][col] = SAND;
                    }
                } else if (mouseSelect == WALL){
                    int col = mouseCol + i;
                    int row = mouseRow + j;
                    if(row >= 0 && row < rows && col >= 0 && col < cols){
                         grid[row][col] = WALL;
                    }
                }
            }
        }
    } else if(IsMouseButtonDown(MOUSE_RIGHT_BUTTON)){
        int matrix = 5;
        int extend = matrix / 2;
        for(int i = -extend; i <= extend; i++){
            for(int j = -extend; j <= extend; j++){
                int col = mouseCol + i;
                int row = mouseRow + j;
                if(row >= 0 && row < rows && col >= 0 && col < cols){
                    grid[row][col] = AIR;
                }
            }
        }
    }
}

void UpdateArray2D(int rows, int cols, int grid[rows][cols], int w){
    //Drawing the Sand
    for(int i = 0; i < rows; i++){
        for(int j = 0; j < cols; j++){
            if(grid[i][j] == SAND){
                DrawRectangle(j * w, i * w, w, w, YELLOW);
            }
            if(grid[i][j] == WALL){
                DrawRectangle(j * w, i * w, w, w, LIGHTGRAY);
            }
        }
    }

    //Create a 2DArray for next frame
    int nextGrid[rows][cols];
    for(int i = 0; i < rows; i++){
        for(int j = 0; j < cols; j++){
            nextGrid[i][j] = AIR;
        }
    }

    //Check every Cell
    for (int i = rows - 1; i >= 0; i--) { // From groundUp
        for (int j = 0; j < cols; j++) {
            int state = grid[i][j];
            if (state == SAND) {
                // Look Down if isn't the last row
                if (i + 1 < rows) {
                    int below= grid[i + 1][j];
                    int belowRight = (j+1 < cols) ? grid[i + 1][j + 1] : 1;
                    int belowLeft  = (j -1 >= 0) ? grid[i + 1][j - 1] : 1;

                    if (below == 0) {
                        nextGrid[i + 1][j] = state;
                    } else {
                        // Choose random direction
                        if (GetRandomValue(0, 1) == 0) {
                            // Right then Left
                            if (belowRight == 0) {
                                nextGrid[i + 1][j + 1] = state;
                            } else if (belowLeft == 0) {
                                nextGrid[i + 1][j - 1] = state;
                            } else {
                                nextGrid[i][j] = state;
                            }
                        } else {
                            // Left then Right
                            if (belowLeft == 0) {
                                nextGrid[i + 1][j - 1] = state;
                            } else if (belowRight == 0) {
                                nextGrid[i + 1][j + 1] = state;
                            } else {
                                nextGrid[i][j] = state;
                            }
                        }
                    }
                } else {
                    //ON THE GROUND!!
                    nextGrid[i][j] = state;
                }
            } else {
                nextGrid[i][j] = state;
            }
        }
    }

    //Update the grid with the nextGrid
    for(int i = 0; i < rows; i++){
        for(int j = 0; j < cols; j++){
            grid[i][j] = nextGrid[i][j];
        }
    }
}

void Draw_SimpleUI(int mouseSelect, Rectangle sand, Rectangle wall){
    DrawRectangleRec(sand, YELLOW);
    DrawRectangleRec(wall, LIGHTGRAY);
    switch (mouseSelect) {
        case 1:
            DrawRectangleLinesEx(sand, 2.5, WHITE);
            break;
        case 2:
            DrawRectangleLinesEx(wall, 2.5, WHITE);
            break;
        default:
            break;
    }
}

int Update_SimpleUI(int mouseSelect, Rectangle sand, Rectangle wall){
    Vector2 mousePosition = GetMousePosition();
    if(CheckCollisionPointRec(mousePosition, sand) || IsKeyPressed(KEY_ONE)){
        return SAND;
    }
    if(CheckCollisionPointRec(mousePosition, wall) || IsKeyPressed(KEY_TWO)){
        return WALL;
    }
    return mouseSelect;
}

int main(){
    //--SETUP--
    InitWindow(WIDTH, HEIGHT, "Falling Sand in C & Raylib");
    SetTargetFPS(60);

    //Creating the Array2D
    int w = 5;
    int cols =  WIDTH/ w;
    int rows = HEIGHT / w;
    int grid[rows][cols];
    int mouseSelect = SAND;

    Rectangle sandButton = {(int)(WIDTH / 2), 10, 40, 20};
    Rectangle wallButton = {(int)(WIDTH / 2) + 50, 10, 40, 20};

    for(int i = 0; i < rows; i++){
        for(int j = 0; j < cols; j++){
            grid[i][j] = AIR;
        }
    }

    while(!WindowShouldClose()){
        //--Input--
        mouseSelect = Update_SimpleUI(mouseSelect, sandButton, wallButton);
        MouseInput(rows, cols, grid, w, mouseSelect);

        //---Draw---
        BeginDrawing();
        ClearBackground(BLACK);

        UpdateArray2D(rows, cols, grid, w);
        Draw_SimpleUI(mouseSelect, sandButton, wallButton);

        EndDrawing();
    }

    CloseWindow();
    return 0;
}