Best way to make tiles not have borders in between them? - c++

Question

So I am trying to make a game using SFML and visual c++. Currently I have different sprites without borders on certain sides for every combination of tiles that could be bordering each other, then used nested if statements to check which sprite to use. However, this slows down my game to the point where I can't even play it. Is there a better way to do this?
Here is my code:
//Render tiles
for (int i = 0; i < blockX.size(); i++) {
block.setPosition(float(blockX[i]), float(blockY[i]));
if (blockType[i] == "metal") {
//if block is metal tile
block.setTexture(metalBlockSingle);
if (doesBlockExist(blockX[i] + 20, blockY[i])) {
//if block is to right
if (doesBlockExist(blockX[i], blockY[i] + 20)) {
//if block is below
if (doesBlockExist(blockX[i] - 20, blockY[i])) {
//if block is to left
if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockCenter);
}
else {
block.setTexture(metalBlockBottomRightLeft);
}
}
else if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockTopBottomRight);
}
else {
//if block is neither above nor to left
block.setTexture(metalBlockBottomRight);
}
}
else if (doesBlockExist(blockX[i] - 20, blockY[i])) {
//if block is to left
if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockTopRightLeft);
}
else {
block.setTexture(metalBlockRightLeft);
}
}
else if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockTopRight);
}
else {
//if block is only right
block.setTexture(metalBlockRight);
}
}
else if (doesBlockExist(blockX[i], blockY[i] + 20)) {
//if block is below
if (doesBlockExist(blockX[i] - 20, blockY[i])) {
//if block is to left
if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockTopBottomLeft);
}
else {
//if block is not above
block.setTexture(metalBlockBottomLeft);
}
}
else {
//if block is not to left
if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockTopBottom);
}
else {
//if metal block is not above
block.setTexture(metalBlockBottom);
}
}
}
else if (doesBlockExist(blockX[i] - 20, blockY[i])) {
//if block is to left
if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockTopLeft);
}
else {
block.setTexture(metalBlockLeft);
}
}
else if (doesBlockExist(blockX[i], blockY[i] - 20)) {
//if block is above
block.setTexture(metalBlockTop);
}
}
window.draw(block);
}
EDIT: Here is the code for the "doesBlockExist" function:
bool doesBlockExist(int x, int y) {
bool returnVal = false;
int findX = int(round(x / 20) * 20);
int findY = int(round(y / 20) * 20);
for (int i = 0; i < blockX.size(); i++) {
if (blockX[i] == findX && blockY[i] == findY) {
returnVal = true;
}
}
return(returnVal);
return(true);
}

Answer 1

Whenever you have nested if-statements (high cyclomatic complexity) like this, you should immediately stop and think about other designs. Large nested if-statements are not only prone to contain mistakes, but are impossible to really understand at a glance.
A better design can start with splitting things into multiple function, each with their own single responsibility. Other steps involve thinking about the logic hard enough to find ways that eliminate conditions, i.e. when situation X holds up, Y follows and there's no need for further checking. And then there are also situations where instead of using if-statements you can construct an object that will have the right settings after construction.
As for optimizations on your code:
Use a sprite sheet and don't use x amount of textures. setTextureRect is basically a free function, while switching textures all the time, can lead to performance issues.
If you keep the implementation of doesBlockExist, at least make sure to return right when you find the block and don't keep iterating. This means, inside the if-body just write return true and after the loop write return false and delete the variable returnVal.
However the doesBlockExist function seems badly implemented. What exactly does it check for? Do you just check the surrounding tiles? If so, then you can easily just check the 8 surrounding tiles and don't need to iterate over all the tiles.
Since you call doesBlockExist quite often, you'll have to think about, whether it wouldn't be possible to just call it once and report on all the surrounding tiles at once.
int(round(x / 20) * 20); since x is already int x / 20 will be an integer division anyways, so there's no reason to round.
Alternatively you could just use a tile editor like Tiled and place the tiles accordingly when designing the level and then just load the tile map.
As for the question in the title, I have no idea what you mean with borders.