Can someone help me with my code. I am trying to get the square to appear on the left side of the window again once it moves off the right side. I almost have it, but once it goes off the right side, it suddenly appears on the left side. I need help making it appear smoothly on the left side of the screen.
Here is my code.
float x = 0;
void setup() {
size(200,200);
}
void draw() {
background(255);
drawRect();
if(x > width+5) {
x = 0;
}
}
void drawRect() {
fill(0);
for (int i = 0; i<width; i+=15){
rect(x +i*2,100,20,20);
}
x = x + 1;
}
I don't really get what the loop in drawRect() does, but it seems like you want to reset x such that the shape it draws is just off the left side of the screen, so something like this:
if (x > width+5) {
x = -50;
}
Related
I am currently working on a very simple 'Falling Sand' simulation game in C++ and SDL2, and am having problems with getting water to flow in a more realistic manner. I basically have a grid of cells that I iterate through bottom-to-top, left-to-right and if I find a water cell, I just check below, down to left, down to the right, left then right for empty cells and it moves into the first one its finds (it makes a random choice if both diagonal cells or both horizontal cells are free). I then mark the cell it moved into as processed so that it is not checked again for the rest of that loop.
My problem is a sort of 'left-bias' in how the particles move; if I spawn a square of water cells above a barrier, they will basically all shift to left without moving once the particles begin to reach the barrier, while the cells on the right will run down in the proper way. So instead of forming a nice triangular shape flowing out evenly to both sides, the whole shape will just move to the left. This effect is reversed whenever I iterate left-to-right, so I know it's something to do with that but so far I've been stumped trying to fix it. I initially thought it was a problem with how I marked the cells as processed but I've found no obvious bugs with that system in many hours of testing. Has anyone faced any similar challeneges in developing a simulation like this, or knows something that I'm missing? Any help would be very much appreciated.
EDIT:
Ok so I've made a little progress, however I've ran into another bug that seems to be unrelated to iteration, since now I save a copy of the old cells and read from that to decide an update, then update the original cells and display that. This already made the sand work better, however water, which checks horizontally for free cells, now 'disappears' when it does move horizontally. I've been testing it all morning and have yet to find a solution, I thought it might've been someting to do with how I was copying the arrays over, but it seems to work as far as I can tell.
New snippets:
Simulation.cpp
void Simulation::update()
{
copyStates(m_cells, m_oldCells); // so now oldcells is the last new state
for(int y = m_height - 1; y>= 0; y--)
for(int x = 0; x < m_width; x++)
{
Cell* c = getOldCell(x, y); // check in the old state for possible updates
switch(c->m_type)
{
case EMPTY:
break;
case SAND:
if(c->m_visited == false) update_sand(x, y);
break;
case WATER:
if(c->m_visited == false) update_water(x, y);
break;
default:
break;
}
}
}
void Simulation::update_water(int x, int y)
{
bool down = (getOldCell(x, y+1)->m_type == EMPTY) && checkBounds(x, y+1) && !getOldCell(x, y+1)->m_visited;
bool d_left = (getOldCell(x-1, y+1)->m_type == EMPTY) && checkBounds(x-1, y+1) && !getOldCell(x-1, y+1)->m_visited;
bool d_right = (getOldCell(x+1, y+1)->m_type == EMPTY) && checkBounds(x+1, y+1) && !getOldCell(x+1, y+1)->m_visited ;
bool left = (getOldCell(x-1, y)->m_type == EMPTY) && checkBounds(x-1, y) && !getOldCell(x-1, y)->m_visited ;
bool right = (getOldCell(x+1, y)->m_type == EMPTY) && checkBounds(x+1, y) && !getOldCell(x+1, y)->m_visited ;
// choose random dir if both are possible
if(d_left && d_right)
{
int r = rand() % 2;
if(r) d_right = false;
else d_left = false;
}
if(left && right)
{
int r = rand() % 2;
if(r) right = false;
else left = false;
}
if(down)
{
getCell(x, y+1)->m_type = WATER; // we now update the new state
getOldCell(x, y+1)->m_visited = true; // mark as visited so it will not be checked again in update()
} else if(d_left)
{
getCell(x-1, y+1)->m_type = WATER;
getOldCell(x-1, y+1)->m_visited = true;
} else if(d_right)
{
getCell(x+1, y+1)->m_type = WATER;
getOldCell(x+1, y+1)->m_visited = true;
} else if(left)
{
getCell(x-1, y)->m_type = WATER;
getOldCell(x-1, y)->m_visited = true;
} else if(right)
{
getCell(x+1, y)->m_type = WATER;
getOldCell(x+1, y)->m_visited = true;
}
if(down || d_right || d_left || left || right) // the original cell is now empty; update the new state
{
getCell(x, y)->m_type = EMPTY;
}
}
void Simulation::copyStates(Cell* from, Cell* to)
{
for(int x = 0; x < m_width; x++)
for(int y = 0; y < m_height; y++)
{
to[x + y * m_width].m_type = from[x + y * m_width].m_type;
to[x + y * m_width].m_visited = from[x + y * m_width].m_visited;
}
}
Main.cpp
sim.update();
Uint32 c_sand = 0xedec9a00;
for(int y = 0; y < sim.m_height; y++)
for(int x = 0; x < sim.m_width; x++)
{
sim.getCell(x, y)->m_visited = false;
if(sim.getCell(x, y)->m_type == 0) screen.setPixel(x, y, 0);
if(sim.getCell(x, y)->m_type == 1) screen.setPixel(x, y, c_sand);
if(sim.getCell(x, y)->m_type == 2) screen.setPixel(x, y, 0x0000cc00);
}
screen.render();
I've attached a gif showing the problem, hopefully this might help make it a little clearer. You can see the sand being placed normally, then the water and the strange patterns it makes after being placed (notice how it moves off to the left when it's spawned, unlike the sand)
You also have to mark the destination postion as visited to stop multiple cells moving in to the same place.
I'm trying out some sample code for a bigger project, and I'm having trouble getting my rectangle to bounce between two lines.
function draw() {
print(frameCount)
background(255)
var x = 150 + frameCount;
rect(x,200,15,15);
line(150,0,150,400);
line(250,0,250,400);
if (x >= 250) {
background(255)
x = 350-frameCount;
rect(x,200,15,15);
line(250,0,250,400);
line(150,0,150,400);
} if (x <= 145) {
background(255)
x = 145 + (frameCount % 100);
rect(x,200,15,15);
line(250,0,250,400);
line(150,0,150,400);
}
}
I'm getting the feeling that after the first instance, it's disregarding the original if statement, which dictates a bounce to the left. I'm really not sure what's going wrong, and any help would be appreciated.
You probably just want to store the current position and speed in a set of variables, and then move the rectangle based on those. Here's an example:
var x = 0;
var speed = 1;
function draw(){
x += speed;
if(x < 0 || x > width){
speed *= -1;
}
background(64);
line(x, 0, x, height);
}
I've written a tutorial on this available here. That's for regular Processing, but the ideas are the same in P5.js.
Sorry if that title isn't very descriptive. Anyway, I am working on something dealing with randomly generating landscapes. I made lakes, but due to how they are make, they often cause straight edges / dropoffs, which aren't desirable. I am trying to smooth it (right after making the lake, if possible), by defining a max variation amount (so land heights cannot vary more than it), and have it fix land if it varies to much, and quit if it is fine.
The problem:
My attempted fix:
As you can see... it didn't work. It also occurs to me, I think it would be broken if it had to move down, although that case shouldn't actually occur, because lakes only ever sink the landscape. Anyway, here is the source of my attempt:
//smoothing land nearby
int maxVariation = 2; //similar to the max height variation when the land is generated
//going right
for (int xPos = rightBound + 1, previousHeight = 0; ; ++xPos)
{
if (previousHeight == 0)
for (; previousHeight < size.y; ++previousHeight)
if (grid[0][rightBound][previousHeight] != BlockColor::DIRT && grid[0][rightBound][previousHeight] != BlockColor::GRASS)
{
--previousHeight;
break;
}
for (int y = 0; y < size.y; ++y)
if (grid[0][xPos][y] == BlockColor::WATER)
goto done_smoothing_right;
int height;
for (height = 0; height < size.y; ++height)
if (grid[0][xPos][height] != BlockColor::DIRT && grid[0][xPos][height] != BlockColor::GRASS)
{
--height;
break;
}
int difference = std::abs(height - previousHeight);
previousHeight = height;
if (difference > maxVariation)
{
for (int j = 0; j < size.y; ++j)
{
int toMove = difference;
while (j + toMove >= size.y)
--toMove;
grid[0][xPos][j] = grid[0][xPos][j + toMove];
}
}
else
goto done_smoothing_right;
}
done_smoothing_right:
int tomakegotowork;
Note that is only the right side, but left should be about the same. How can I do this correctly?
Thanks if you can help.
EDIT:
I never did solve this problem. Instead, I made a recursive function to measure air, (from a certain height), and if a pocket of air (formed by the land) had enough, to fill with water. This has the advantaged of the land looking smooth because it is not altered.
This is written in java so you will need to convert it to c++ but it should give you the basic idea. It will only work for smoothing upwards as well and I only did the right side of the lake but it is very easy to modify it for the left side of the lake. I tried to match what I think the functionality of your code is.
Hope it helps...
void smoothLakeRight(Lake lake){
int x = lake.rightBound+1;
if(getGrassHeight(x)-lake.height>WorldConstants.MAX_LAKESIDE_VARIATION){
//if the right bank is too high start smoothing
int y =lake.height+WorldConstants.MAX_LAKESIDE_VARIATION;
while(grid[0][x][y] == BlockColor.DIRT){
fixGrass(x++, y++);
}
}
}
private int getGrassHeight(int xPos){
int y = WorldConstants.LOWEST_GRASS;
while(grid[0][xPos][y++] != BlockColor.GRASS);
return y-1;
}
private void fixGrass(int xPos, int yPos){
grid[0][xPos][yPos] = BlockColor.GRASS;
aboveAir(xPos,yPos);
belowDirt(xPos, yPos);
}
private void aboveAir(int xPos, int yPos) {
while(grid[0][xPos][++yPos]!=BlockColor.AIR){
if(grid[0][xPos][yPos]==BlockColor.TREE){
upRootTree(xPos, yPos);
}else{
grid[0][xPos][yPos]=BlockColor.AIR;
}
}
}
private void upRootTree(int xPos, int yPos) {
while(grid[0][xPos][yPos]==BlockColor.TREE){//remove stump
grid[0][xPos][yPos++]=BlockColor.AIR;
}
//remove leaves
grid[0][xPos][yPos] = BlockColor.AIR;
grid[0][xPos+1][yPos] = BlockColor.AIR;
grid[0][xPos-1][yPos] = BlockColor.AIR;
grid[0][xPos+1][yPos-1] = BlockColor.AIR;
grid[0][xPos-1][yPos-1] = BlockColor.AIR;
}
private void belowDirt(int xPos, int yPos) {
while(grid[0][xPos][--yPos]!=BlockColor.DIRT){
grid[0][xPos][yPos] = BlockColor.DIRT;
}
}
I'm trying to make a platformer game in C++ and I have made a vector of blocks,
and I simply loop through the vector and check for the collision individually:
//Pseudo code
class Block{
...int x
...int y
...int width
...int height
};
class Player{
int x
int y
int width
int height
int hsp //horizontal speed
int vsp //vertical speed
int facing //0 = no direction, -1 = left, 1 = right
...
void loop()
{
if(keyboard_pressed(key_left) { x-=hsp; facing = -1;}
if(keyboard_pressed(key_right) {x+=hsp; facing = 1;}
if(keyboard_pressed(key_up) {y-=vsp;}
if(keyboard_pressed(key_down) {y+=vsp;}
if(keyboard_released(key_left | key_right) {facing = 0;}
for(int i = 0; i < blocks.size(); i++)
{
Block b = blocks.at(i);
check_Collision(b);
}
}
};
As you can see, my player simply moves according to hsp and vsp. Simple enough.
The main portion of my question is in check_Collision(). First I check to see if the player
is on top of the block, and if he is, let him stay there.
Then I check if the player is at the sides of the block.
But for some reason there's a problem. For some reason when I go under the top of the block,
he stays at the top, but then he gets shifted to the left side.
I honestly don't know where to go with this.
The following code only checks for the top and the left side:
check_Collision(){
///////////////////////////////////
var myLeft, myRight, myTop, myBot;
var bLeft, bRight, bTop, bBot;
myLeft = x;
myRight = x + width;
myTop = y;
myBot = y + height;
/////////////////////
bLeft = b.x;
bRight = b.x + b.width;
bTop = b.y;
bBot = b.y + b.height;
//////////////////////////////////
//Check if we are at the top
if(myBot + vsp > bTop+1){
y = bTop - height;
}
//Check if we are at the sides
if(myBot > bTop+2){
if(myRight + hsp > bLeft)
{
x = bLeft - width;
}
}
}
If anyone can point me into some tutorial on 2D box collision that would be great.
The logic you're using doesn't make sense to me. It's not enough just to check that the player is under the block: don't you also need to make sure that the player is standing on it, ie, isn't too far to the right or left of the block? Similarly, in your second check, you've got to make sure that the player isn't jumping over the block (or standing on it). Your if partially checks this, but doesn't take into account the fact that the first check might have modified player position.
Can you assume that the player can't ever walk under the block? Can you assume that the player will never move fast enough to "tunnel" completely through the block (hsp > b.width, etc)?
If the answer to either of these is no, you will need significantly more sophisticated collision detection.
http://tinypic.com/r/fwubzc/5
That shows what a flip should be and what a mirror should be.
Code for both types of mirrors:
void mirrorLeftRight()
{
for (int x = 0; x < width/2; x++) {
for (int y = 0; y < height; y++) {
int temp = pixelData[x][y];
pixelData[x][y]=pixelData[width-x][y]
pixelData[width-x][y]=temp;
}
}
}
void mirrorUpDown()
{
for (int x = 0; x < width; x++) {
for (int y = 0; y < height/2; y++) {
int temp = pixelData[x][y];
pixelData[x][y]=pixelData[x][height-y]
pixelData[x][height-y]=temp;
}
}
}
Does this seem right for mirrors?
And for flip, just a matter of using width and height w/o dividing by 2?
You need to use width-1-x instead of width-x, and height-1-y instead of height-y. Otherwise for x==0 you'll try to index [width], which is outside the array.
It shouldn't work since you are swapping pixels while you just have to override the right part of the image with the left part. Same thing applies to the mirrorUpDown.
If you swap them you obtain a flip, if you overwrite them you obtain a mirror.
mirrorLeftRight: take pixels from left half and use them to overwrite right part
mirrorUpDown: take pixels from upper part and use them to overwrite lower one
flip: in this case you don't overwrite but you swap pixels (source half it's not influent in this case)
The code above seems more like the correct way to Flip, not mirror.
Mirror I would guess that you not switch the pixels, but rather copy from one side to the other.
With mirror I would guess that you need to change
int temp = pixelData[x][y];
pixelData[x][y]=pixelData[width-x][y]
pixelData[width-x][y]=temp;
to something like this only
pixelData[x][y]=pixelData[width-x][y]