Hi! Right now I'm working on some kind of runtime for scratch on C++.
The goal is to make it as fast as possible losing no readability of the resulting scripts.
E.g make it fast without translation-time optimizations.

Example project: (https://github.com/MiloLug/c-scratch).
The scripts.h file is actual scripts file for sprites.
The sprites.h file is for sprites list specification (like position, visible/not visible etc.).
This is exact representation of our (with my friend, Luna) light simulation, how it should be (ideally) generated.

So the code will look like this:

Coroutine spriteStartScript2(Sprite * sprite) {
forever {
waitUntil(v_tick == 100);
v_timer = timer;
v_tick = 0;

// don't have graphical output rn, so it's just like this
wprintf(L“timer = %ls\n”, v_timer.toString());

cs_yield;
}

stopThisScript();
}

It already has full support of strings and numbers (even in one variable), almost full support for control blocks and motion.
It also allows many sprites and has pen support, except for non-RGB color-setting functions like saturation, brightness etc.

The problem is that we need to generate it after all :) :)
So my question is HOW…

Right now we stick to Snap, but it seems too hard and not well documented way. Also it would be good to not depend on side projects. There is a case already, when it was updated incompatible with our parser.

So I basically need at least a hint…

P.S. The example project works fine. But it's hard to set it up on Windows. So you can try to run it on Linux. You need to install libraries from the requirements, then run

cmake .

And

make

And then just run the app executable

I can contribute because i undestand C++

Also if we need to use graphics, we use graphics.h or OpenGL.

Oh that's cool. The code is a mess right now tho. Since it's been a week or two and I was just trying to get to the point when I can run our project.
And it has graphics already. We decided to use SDL for graphics, since It has also audio, keyboard and other features support

So right now I'm going to do some refactoring before it gets too far

It's better interpret the project, and make it use libcurl to get the project's SB3 contents, i also suggest making it into seperate files, the easiest one without command-line arguments is .cpp,

anyways i use mingw because i cannot use ubuntu because of size.

The project.json file has a list of all the blocks and scripts; you can search for hat blocks and blocks stemming from them, including the variables and the sprites included, and eventually just generate the code from all of that.

lolecksdeehaha wrote:

The project.json file has a list of all the blocks and scripts; you can search for hat blocks and blocks stemming from them, including the variables and the sprites included, and eventually just generate the code from all of that.

yeah you can use this library to parse json and do something with it.

Well it would be better if the goal wasn't the speed of execution and further code editing possibility. Cause in case of interpreting the project, you can't rely on the c++ compiler optimizations. You can either interpret it with a recursion or by making some byte-code layer, and both these options are not as good as just translating to c++. The first one is too slow and the second is just horrible in terms of development effort

WojtekGame wrote:

lolecksdeehaha wrote:

The project.json file has a list of all the blocks and scripts; you can search for hat blocks and blocks stemming from them, including the variables and the sprites included, and eventually just generate the code from all of that.

yeah you can use this library to parse json and do something with it.

Oh.. I will look into this. Thank you

OH BUT we could use the runtime as a lib for such interpreter. Just as an option. I mean, stick to the translation way, but also make an interpreter project that uses the runtime part to interpret SB3.

liavka wrote:

Well it would be better if the goal wasn't the speed of execution and further code editing possibility. Cause in case of interpreting the project, you can't rely on the c++ compiler optimizations. You can either interpret it with a recursion or by making some byte-code layer, and both these options are not as good as just translating to c++. The first one is too slow and the second is just horrible in terms of development effort

i don't think compiling is a good option, unless you want to add it…

That'll be a very difficult task. Scratch has lots of weird quirks and so does JavaScript. For example, many of the following are present:
There are more, but they probably don't apply to Scratch. It's very difficult to create weird auto-conversions for everything, so good luck!

Spentine wrote:

That'll be a very difficult task. Scratch has lots of weird quirks and so does JavaScript. For example, many of the following are present:

console.log(Number("0x1") + 1) // 2
console.log(Number("0b11") + 1) // 4
console.log(Number("0o11") + 1) // 10

There are more, but they probably don't apply to Scratch. It's very difficult to create weird auto-conversions for everything, so good luck!

these aren't quirks they're just additions in different bases

Spentine wrote:

That'll be a very difficult task. Scratch has lots of weird quirks and so does JavaScript. For example, many of the following are present:

console.log(Number("0x1") + 1) // 2
console.log(Number("0b11") + 1) // 4
console.log(Number("0o11") + 1) // 10

There are more, but they probably don't apply to Scratch. It's very difficult to create weird auto-conversions for everything, so good luck!

Well… As I've said the strings/numbers are implemented rn, so I can

str1 = “some22Test”
str2 = letterOf(str1, 5)
num = str2 + 10
// num = 12 now

I even have some tests file I use while developing features, and there is a good example:

Value var1 = 1;
Value var2 = var1 + 15;
Value someVar = var2.toString();
Value test = someVar == (var1 + 15);
ValueArray testArr({1, 2, L“gg 10”});

wprintf(L“out1: someVar = %ls; test = %ls\n”, someVar.toString(), test.toString());

test = join(join(join(join(var1, L“ + ”), 15), L“ = ”), someVar);

wprintf(
L“out2: %i\n”,
join(join(join(join(var1, L“ + ”), 15), L“ = ”), someVar) == L“333 + 15 = 348”
);
wprintf(L“out3: %ls\n”, test.toString());

test = 20 + join(1, 50);
wprintf(L“out4: %ls\n”, test.toString());

test = letterOf(test, 2) + 20;
wprintf(L“out5: %ls\n”, test.toString());

test = testArr;
testArr.push(testArr);
test = join(L“testArr = ”, testArr);
wprintf(L“out7: %ls\n”, test.toString());

WojtekGame wrote:

liavka wrote:

Well it would be better if the goal wasn't the speed of execution and further code editing possibility. Cause in case of interpreting the project, you can't rely on the c++ compiler optimizations. You can either interpret it with a recursion or by making some byte-code layer, and both these options are not as good as just translating to c++. The first one is too slow and the second is just horrible in terms of development effort

i don't think compiling is a good option, unless you want to add it…

Well.. I actually want to do it

liavka wrote:

Spentine wrote:

That'll be a very difficult task. Scratch has lots of weird quirks and so does JavaScript. For example, many of the following are present:

console.log(Number("0x1") + 1) // 2
console.log(Number("0b11") + 1) // 4
console.log(Number("0o11") + 1) // 10

There are more, but they probably don't apply to Scratch. It's very difficult to create weird auto-conversions for everything, so good luck!

Well… As I've said the strings/numbers are implemented rn, so I can

str1 = “some22Test”
str2 = letterOf(str1, 5)
num = str2 + 10
// num = 12 now

I even have some tests file I use while developing features, and there is a good example:

Value var1 = 1;
Value var2 = var1 + 15;
Value someVar = var2.toString();
Value test = someVar == (var1 + 15);
ValueArray testArr({1, 2, L“gg 10”});

wprintf(L“out1: someVar = %ls; test = %ls\n”, someVar.toString(), test.toString());

test = join(join(join(join(var1, L“ + ”), 15), L“ = ”), someVar);

wprintf(
L“out2: %i\n”,
join(join(join(join(var1, L“ + ”), 15), L“ = ”), someVar) == L“333 + 15 = 348”
);
wprintf(L“out3: %ls\n”, test.toString());

test = 20 + join(1, 50);
wprintf(L“out4: %ls\n”, test.toString());

test = letterOf(test, 2) + 20;
wprintf(L“out5: %ls\n”, test.toString());

test = testArr;
testArr.push(testArr);
test = join(L“testArr = ”, testArr);
wprintf(L“out7: %ls\n”, test.toString());

is this just converting sb3 to .cpp?

this can be a option but having a bare bones exe is also good, but it will just show the sdl gui.

WojtekGame wrote:

liavka wrote:

Spentine wrote:

That'll be a very difficult task. Scratch has lots of weird quirks and so does JavaScript. For example, many of the following are present:

console.log(Number("0x1") + 1) // 2
console.log(Number("0b11") + 1) // 4
console.log(Number("0o11") + 1) // 10

There are more, but they probably don't apply to Scratch. It's very difficult to create weird auto-conversions for everything, so good luck!

Well… As I've said the strings/numbers are implemented rn, so I can

str1 = “some22Test”
str2 = letterOf(str1, 5)
num = str2 + 10
// num = 12 now

I even have some tests file I use while developing features, and there is a good example:

Value var1 = 1;
Value var2 = var1 + 15;
Value someVar = var2.toString();
Value test = someVar == (var1 + 15);
ValueArray testArr({1, 2, L“gg 10”});

wprintf(L“out1: someVar = %ls; test = %ls\n”, someVar.toString(), test.toString());

test = join(join(join(join(var1, L“ + ”), 15), L“ = ”), someVar);

wprintf(
L“out2: %i\n”,
join(join(join(join(var1, L“ + ”), 15), L“ = ”), someVar) == L“333 + 15 = 348”
);
wprintf(L“out3: %ls\n”, test.toString());

test = 20 + join(1, 50);
wprintf(L“out4: %ls\n”, test.toString());

test = letterOf(test, 2) + 20;
wprintf(L“out5: %ls\n”, test.toString());

test = testArr;
testArr.push(testArr);
test = join(L“testArr = ”, testArr);
wprintf(L“out7: %ls\n”, test.toString());

is this just converting sb3 to .cpp?

this can be a option but having a bare bones exe is also good, but it will just show the sdl gui.

Right now it doesn't exactly convert sb3, but rather a snap project through some snap magic. But in fact, yes, we just convert projects to c++.
But you can easily use the same runtime to create an interpreter. It's not some hardcoded environment at all. You can dynamically add new coroutines, sprites etc

Sooo we almost have mouse support and I also found some good SDL2 GUI libraries. It seems, it won't be too hard to add gui input/output rn

Nice project! Maybe you could add some previews when GUI support arrives?