2D Godot raycastin is unituitive to use & 2D Global coordinates and rotation - godot
Hey so i am working on a interactive mini game in my work. New to godot!
Item.rotate(rand_range(-1.22173,1.22173)) just shooting missiles apromaxily 70 degrees at random. Its doing more like 140 degrees and i don't know why when i rotate.
Item = ammo.instance()
Item.position = Vector2(960,0)
Item.rotate(rand_range(-1.22173,1.22173))
add_child(Item)
bulletArray.append(Item)
var rot = Item.rotation
angle = rot + PI/2
angleArray.append(angle)
then when i shoot it with bullet array loop:
x.position += Vector2(1, 0).rotated(angleArray[index]) * speed * delta
its like 1-3 degreees off sometimes you can slightly notice it so its weird.
I wanted raycasting to just use some visual elements there maybe add collider later dont know. I tried
var randomvec = Vector2(rand_range(-400, 1120),1080)
with local coordinates when y is = 0 window size is 1080 y. It jus shoots so much wider than it should. And theres no documentation i can find. when i used something more like ((-30,30),1080)*MAX (max was = 1050) i was getting better results.
Is there any reliable way to use global coordinates on 2D games. Mostly for everything.
Thanks ! Just trying something new to this engine.
Its good enough but its not perfect angle how to fix that ?
I tried those codes shooting works and angle is 98% perfect. Raycasting was really hard to get on right area on random. Tried looking some documentation but cant figure it out.
Easy way to just use global coordsinates for almost everything ?
Okay im an idiot im working 12 hours a daý..... i just need to Item.rotate(rand_range(-1.22173,1.22173)) / 2 Sorry about that im really overworking..... of course its 140 degrees.... but raycasting question and angle couple degrees off still stands. It was still better gameplay when it was little wider so i try 90 pii/2. lol haha. Need to have a break.
As you must have figured out 1.22173 radians is 70º. Which means the range from -1.22173 to 1.22173 is a range from -70º to 70º which is a total of 140º.
I will also remind you that you can use the to_local and to_global methods to convert from and to global coordinates.
Furthermore in 2D you can use global_rotation.
And if you want to transform a direction, you can use node2d.global_transform.basis_xform(direction) (or use basis_xform_inv for the inverse).
its like 1-3 degreees off sometimes you can slightly notice it so its weird.
I'm guessing this is floating point error. Work with the rotated direction (a unit vector), instead of storing an angle and rotating again. Or use the transform of the Node2D as mentioned above.
Related
change max steepness of slope character can climb godot
I am making a platformer game with all the basic code that is usualy found in godot platformers(kinimaticbody2d,move_and_slide, etc). the problem is that the character can climb really steep slopes which I dont like. for example the character can move up the slope shown in the picture simply by pressing left(no jumping) he just slowly slides up but when i make the slope just a little bit steeper the character cant scale the slope. my question is there a way to set the maximum angle of a slope that a character can climb? thx in advance
If you are using move_and_slide you need to: Specify an up_direction vector, which goes into the second parameter of move_and_slide. Without it, everything is considered a wall, and no sliding happens. Since, you are experiencing sliding, I suspect you already have this. And specify floor_max_angle float, which goes into the fifth parameter of move_and_slide. This controls how inclined can be a surface and still be considered a floor/slope. If a surface is more steep that this angle, it will be considerad a wall, and no sliding happens. The angle is measured between the normal of the surface and the up_direction vector provided. By default the value of floor_max_angle is 0.785398 (it is in radians, by the way) which is equivalent to 45º. The situation you are suggest you are using a number closer to a quarter turn (i.e π/2 - approx 1.57 - radians). Probably something like 1.2 or 1.3? You want a smaller value. By the way, you can convert from radians to degrees with rad2deg and viceversa with deg2rad. I'll quickly go over a couple more issues you may find along the way: The character slides down when idle due to gravity. To prevent this, you want to set stop_on_slope to true. This is the third parameter of move_and_slide. The character have jitter and move more than desired when going down the slope with user input (caused by very little jumps usually perceived as jitter). And this is why you would want to move_and_slide_with_snap, which has an extra snap vector parameter which allows you to specify a direction the character should stick to the ground while moving. By the way, you may want to use get_slide_collision to figure out on what surface the character did slide, if any, and what is its normal.
Triangle of particular size with Python turtle graphics
I am still quite new to Python and I would like to create a program which would draw geometry objects of given size. For example how would I create the triangle with the sides of 7cm, 6 cm and 5 cm? Any hint would be very appreciated.
do you want the sizes to be user inputted?
if you do, in my experience I created a loop with the colour and amount of rectangles they wanted by using x=int(number) then for i in range(x): this allowed the user to choose how many rectangles. Before hand I put in an input code to get the answer print("how many rectangles do you want?") and number = input("I want this many rectangles:")
Although it isn't the exact same, if you know what numbers equals what distance you want, then you could redo the x=int(number) for each side and instead move the x from the code i mentioned before to the moving codes. eg,forward(x)
I hope that helped, let me know if you don't understand
Triangulate camera position and orientation in regards to known objects
I made an object tracker that calculates the position of an object recorded in a live camera feed using stereoscopic cameras. The math was simple, once you know the camera distance and orientation. However, now I thought it would be nice to allow me to quickly extract all these parameters, so when I change my setup or cameras I will be able to quickly calibrate it again. To calculate the object position I made some simplifications/assumptions, which made the math easier: the cameras are in the same YZ plane, so there is only a distance in x between them. Their tilt is also just in the XY plane. To reverse the triangulation I thought a test pattern (square) of 4 points of which I know the distances to each other would suffice. Ideally I would like to get the cameras' positions (distances to test pattern and each other), their rotation in X (and maybe Y and Z if applicable/possible), as well as their view angle (to translate pixel position to real world distances - that should be a camera constant, but in case I change cameras, it is quite a bit to define accurately) I started with the same trigonometric calculations, but always miss parameters. I am wondering if there is an existing solution or a solid approach. If I need to add parameter (like distances, they are easy enough to measure), it's no problem (my calculations didn't give me any simple equations with that possibility though). I also read about Homography in opencv, but it seems it applies to 2D space only, or not? Any help is appreciated!
insertObservation method in COccupancyGridMap2D is producing warped results
The function insertObservation in COccupancyGridMap2D takes in two parameters which are the CPose3D and CObservation2DRangeScan values, even though both of these values are accurate with no noise, the grid is producing warped boundaries. The only thing I can think of is the scan.aperture settings might be producing this effect but these are correct with a range of 2*PI and other visual aides for point clouds show no warpage at all. Below is an illustration of this.
On the right the occupancy grid is warped compared to the ground truth square boundary. The left points look fine and are using the same aperture and load FromVectors settings.
Here is example code to try to verify the warp effect your self.
COccupancyGridMap2D gridmap;
gridmap.setSize(-4.0,4.0,-4.0,4.0,0.025f);
#define SCANS_SIZE 100
char SCAN_VALID[] = {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1};
CPose3D transform = CPose3D(0,0,0,0,0,0);
CObservation2DRangeScan read_scan;
read_scan.aperture = 2*M_PIf;
read_scan.rightToLeft = true;
vector<float> landmark = {2.9f,2.906f,2.924f,2.953f,2.996f,3.052f,3.124f,3.212f,3.319f,3.447f,3.601f,3.786f,4.007f,3.948f,3.736f,3.560f,3.413f,3.290f,3.188f,3.104f,3.037f,2.984f,2.945f,2.918f,2.903f,2.900f,2.909f,2.930f,2.963f,3.009f,3.069f,3.144f,3.237f,3.349f,3.483f,3.644f,3.837f,4.069f,3.891f,3.689f,3.521f,3.380f,3.263f,3.166f,3.086f,3.022f,2.973f,2.937f,2.913f,2.901f,2.901f,2.913f,2.937f,2.973f,3.022f,3.086f,3.166f,3.263f,3.380f,3.521f,3.689f,3.891f,4.069f,3.837f,3.644f,3.483f,3.349f,3.237f,3.144f,3.069f,3.009f,2.963f,2.930f,2.909f,2.900f,2.903f,2.918f,2.945f,2.984f,3.037f,3.104f,3.188f,3.290f,3.413f,3.560f,3.736f,3.948f,4.007f,3.786f,3.601f,3.447f,3.319f,3.212f,3.124f,3.052f,2.996f,2.953f,2.924f,2.906f,2.900f};
float *SCAN_RANGES = &landmark[0];
read_scan.loadFromVectors(SCANS_SIZE, SCAN_RANGES,SCAN_VALID);
gridmap.insertObservation(&read_scan,&transform);
CSimplePointsMap m3;
m3.insertObservation(&read_scan);
m3.getAllPoints(map_xs,map_ys,map_zs);
Here is a image of the simplePointsMap plot (red points) vs the OccupanyGrid
The angles being casted from the occupany grid look correct, with a consistent interval, but the angle is still off from simplepoints map, length looks ok and it seems each ray could be rotated to match with one of the red points. Possibly what could be happening is a mapping issue, and since we try to make the angles into discrete horizontal and vertical steps this causes the misalignment. I've tried increasing the resolution but this does not help, I guess that makes sense since scaling a horizontal/vertical ratio would still result in the same ratio and mismatch. I might be missing something though, what else could be causing this distortion, is this expected and the best we can do? Thank you for any help.
It seems to me that the problem is in the assumption of which are the angles of each scan "ray". Take a look at the class mrpt::obs::CSinCosLookUpTableFor2DScans, generate one such sin/cos LUT for your specific scan object, and double check if the sin/cos values coincide with yours, as used to generate the scan. By the way, COccupancyGridMap2D has one method to simulate a 2D scan from a gridmap image, give it a try, and if that one generates warped results, please fill up a bug report (!) ;-) Cheers.
I just realized what was going on, CSimplePointsMap and COccupancyGridMap2D use two slightly different references for point angles. CSimplePointsMap is expecting an overlap between the first and last point while COccupancyGridMap2D is not. The simple fix to all of this then is to read in one less scan for the COccupancyGridMap2D and then everything lines up. This is if your angles are being defined as so, which is fine for CSimplePointsMap.
for (int i = 0; i < Raysize; i++)
{
float angle = -angle_range / 2 + i * (angle_range) / (Raysize-1);
Here is the fix for OccupancyGridMap2D insertObservation using SCANS_SIZE-1 instead and CSimplePointsMap can still use SCANS_SIZE.
read_scan.loadFromVectors(SCANS_SIZE-1, SCAN_RANGES,SCAN_VALID);
gridmap.insertObservation(&read_scan,&transform);
Game Programming - Billboard issue in front of 3D object
I'm starting to develop a poc with the main features of a turn-based RPG similar to Breath of Fire 4, a mixture of 3D environment with characters and items such as billboards. I'm using an orthographic camera with an angle of 30 degrees on the X axis, I did my sprite to act as a billboard with the pivot in the center, the problem occurs when the sprite is nearing a 3D object such as a wall. Check out the image: I had tried the solution leaving the rotation matrix of the billboard "upright", worked well, but of course, depending on the height and angle of the camera toward the billboard it gets kinda flattened, I also changed the pivot to the bottom of the sprite but this problem appears with objects in front of the sprite too. I was thinking that the solution would be to create a fragment shader that relies on the depth texture of some previous pass, I tried to think in how to do it with shaders but I could not figure it out. Could you help me with some article or anything that puts me in the right direction? Thank you. See what I am trying to achieve on this video.
You had got the right approach. Use the upright matrix, and scale up Z of billboards preparing flattened Z by your camera. The Z scaling should be about 1.1547. It is (1 / cos30), which makes billboards look like original size from the camera with the angle of 30 degrees. It seems a tricky way but developers of BoF4 on the video might use the same solution too.