R0J0hound's Forum Posts

  • If the player is moved with the physics behavior too, then no, not with the bundled physics behavior since there is no collision filtering.

    There are other physics plugins such as chipmunk physics you can download and use instead. It for instance has a setting called collision mask for any object using the behavior.

    Set the player to 01

    The enemies to 10

    Any walls both hit to 11

    And walls only the player can walk through to 10

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  • It should just bounce. You shouldn’t need to apply an impulse at all.

  • It probably can be simplified to:

    rotate clockwise by (mouse.x-self.x)*k

    Where k is to tune the rotation amount

  • The terrain is just a graph. For any x position you just need a way to calculate a y.

    A simple start would be y=sin(x)

    Or to center it vertically and make the hills bigger you can do y=240+100*sin(x)

    There are many ways to make the terrain more interesting than just a sine wave. You can use a noise plugin, or maybe add multiple sine waves together. Another idea is to just fill an array with random numbers and use cosp() to interpolate smoothly between the numbers.

    So basically a function like this:

    Function terrain(x)

    — i = int( x/100)

    — t = x/100 -i

    — return cosp(array.at(i),array.at(i+1),t)

    Then you can move the player around in any way you like, and you can know if it hit the ground if player.y > function.call(“terrain”, player.x)

    I don’t really want to fight with constructs collision system to somehow make it work with this, so instead you can do it manually. It’s also simple enough to do your own motion with a vx and vy variable.

    Every tick

    — add 200*dt to player.vy

    — add player.vx*dt to player.y

    — add player.vy*dt to player.y

    Set y0 to function.call(“terrain”, player.x)

    Set y1 to function call(“terrain”, player.x + 0.001)

    Set ang to angle(0,y0,0.001,y1)

    Player.y > terrain(player.x)

    — set player.y to y0

    — set dot to player.vx*cos(ang)+player.vy*sin(ang)

    — set player.vx to dot*cos(ang)

    — set player.vy to dot*sin(ang)

    So far so good. I guess I forgot to cover a way to draw the terrain. You could get away with only drawing what’s on screen.

    Destroy circle

    Repeat 100 times

    — create circle at (0,0)

    — set x to lerp(leftScreen, rightscreen, loopindex/99)

    — set y to function.call(“terrain”, self.x)

    You could also stretch rectangle sprites between the circles to give a continuous line.

    To fill the area below you could use all the circle locations along with the bottom two corners of the screen with a canvas fill function.

    The gradients would require reasoning about how you’d want it to look and maybe drawing an offset polygon or placing blurred scaled sprites at key spots.

    EDIT:

    working example.

    dropbox.com/s/q9vpfm2psqr4qfe/terrain_physics.capx

  • dop2000

    Ah, I hadn’t tested it, good to know. I guess in that case it would be a false positive if the imagepoint was actually the same as the origin.

  • That would have to be done inside the plugin, and that’s what save/load actually does. However, no, there’s nothing implemented on that front.

    You can use the canvas.asjson expression to get some json that can be loaded into the array object, but it’s not reversible.

  • I think you mean imagepoint? All objects have an origin and I didn’t think you could rename it.

    If you just access an imagepoint x or y with an expression and if it’s equal to 0 the will mean it doesn’t exist. Usually at least, if you have the sprite near the top left edges of the layout the imagepoint could have zero coordinates. In that case you’d want to move the sprite to a location far away first, then after your check move it back.

  • To mirror around the center of the screen:

    scrollx-(mouse.x-scrollx)

    I've also used

    640-mouse.x

    Where 640 is the screen width, and the you don't do any scrolling.

  • Here's another idea too. The crux is a compare like the following to see if any of the text matches what was typed.

    compare textbox.text = left(text.text, len(textbox.text))

    dropbox.com/s/55xlnwskmv7dy0d/search_system_test.capx

    And then I realized some simplifications:

    dropbox.com/s/9gwsv0q7yugzv1c/search_system_test_2.capx

  • Worst case you can use canvas.imageUrl to get a save of the canvas image. Then to load it you’d take a sprite at the same position as the canvas, load the imageUrl into an animation frame of the sprite, set the sprite size to the same size as the canvas, clear the canvas, and finally paste the sprite into the canvas.

    On a side note the plugin did save/load the image at some point. It possibly could have been disabled in code since it was slow, but I don’t recall. I don’t use the plugin anymore and have ceased any development on the plugin itself to fix issues that crop up.

    I am happy to try to help with usage questions when I can. Probably not with examples, since I don’t have it installed, but maybe I can help point you in the right direction.

  • I agree, the shunting yard algorithm, and reverse polish notation wouldn't be suitable for anything beyond expressions. I've found recursive decent to be awkward and abstract when dealing with precedence, could be just me though. I'm not sure what class of parser I currently utilize falls under but if I wanted to generate a ast I've used the following which I'll drop for reference. It looks similar to the shunting yard algo.

    en.wikipedia.org/wiki/Operator-precedence_parser

    There are pros and cons to different methods for sure. A lot comes down to personal preference. The method I used seems to make it fairly easy to change up the syntax rules and add stuff. Here i added some math functions and 2d vector types to the expression. Along with type checking, but the error messages could be nicer.

    dropbox.com/s/paqwch9pke1pvms/parser_test5_with_vec.capx

  • Parsing is a matter of converting text to a list of tokens, and verifying there were no syntax errors. Actually I've found the error checking to be the more involved part.

    Anyways here's my two cents on top of what has been mentioned. I'd go this route:

    1. Convert text to a list of tokens. Basically numbers and operators (+-*/).

    2. Convert the list of tokens from infix notation to reverse polish notation (RPN) using:

    en.wikipedia.org/wiki/Shunting-yard_algorithm

    That will eliminate the parenthesis and make it much simpler to calculate the result. An expression tree is another option but the code to do so in Construct will be more involved.

    3. Evaluate the RPN expression to get the result.

    Here's the current way I've gone about it. 61 fairly organized events although I can see shaving that down further. Handles decimal numbers, the five math operations (+-*/^), parenthesis and negation.

    dropbox.com/s/f7lzeykvp98j1mw/parser_test3.capx

    Older stuff:

    106 events. Same capabilities as the one above. The approach is fairly different. Error checking is done by looking at neighboring tokens to see if it makes sense.

    dropbox.com/s/36fg2ook2g0850o/parser.capx

    70 events with a similar error checking method. Doesn't have ^ but it lets you write expressions like you do on paper with some variables. ex: 2(3), 4x+5y, etc...

    dropbox.com/s/29i3dv40hk4ll1b/simpleEval.capx

    You can also just use the browser.execjs() expression to evaluate the expression. The main disadvantage of that is the user can run any js with it. Not really an ideal situation. You could use a complicated regex expression to verify it only contains stuff you want, or maybe there's other approaches. The second disadvantage is you lose the ability to show good error messages if a bad expression is written.

  • Sorry for the late reply. I can’t say what’s amiss. I have the bad habit lately of not verifying my ideas work correctly. I just haven’t had time to test or debug anything.

    I don’t think I’m much help very often on here anymore. The issue could be with how the conversions are applied, or maybe the conversions are off, or could be the top of my head math and logic are flawed. I’ve buried myself to solve all that and I’m not able to work though it at this time.

  • No idea what topic it was.

    As a quick idea you can loop over all the tile positions, place a square sprite on the tile, and then check for an overlap between that sprite and the other object. If it overlaps, then the current tile is touching the object.

  • Here’s the math for it where dist is the distance to move before stopping and f is the braking force.

    Global number f = -200

    Global number dist = 2000

    Start of layout

    — apply impulse self.mass*sqrt(-2*dist*f/self.mass)

    Velocityx > 0

    — apply force f

    Anyways that would work fairly well. However the units are off with the physics behavior. Here is the info on how to convert the units so the formulas above would work.

    construct.net/en/forum/construct-2/general-discussion-17/math-physics-83966

    As a personal view I find it annoying to convert even though I found the conversions. It’s often simpler to just not use the physics behavior.

    For instance if you used the bullet behavior instead you could set the acceleration to -200 and set the initial velocity to sqrt(-2*dist*-200) and get the same result.