This is for anyone who's having trouble getting started with cairo.
The documentation didn't give a good, complete example. That's why I wanted to share this.
I created a concrete example which you can put in your rc.lua and play with it.
local wibox = require('wibox')
local cairo = require("lgi").cairo
local surface = cairo.ImageSurface(cairo.Format.RGB24,20,20)
local cr = cairo.Context(surface)
my_wbox = wibox()
my_wbox.visible = true
my_wbox:set_bg("#ff0000")
cairo_widget = wibox.widget.base.make_widget()
cairo_widget.fit = function(context, width, height)
return 100, 100
end
cairo_widget.draw = function(self, my_wbox, cr, width, height)
cr:translate(100, 100)
cr:set_source_rgb(0,0,0)
cr:rectangle(0, 0, 100, 100)
cr:fill()
end
my_wbox:set_widget(cairo_widget)
my_wbox:geometry({x=50, y=50, width=500, height=500})
There is https://awesomewm.org/apidoc/documentation/04-new-widgets.md.html, but I guess that page does not have a "here is everything in one copy-able chunk" at the end.
Related
In the SceneKit WWDC 2014, they have an example of a vortex field with this effect:
The particle system looks much like a tornato, as it spins inward with a hollow center.
However, the documentation for vortex fields have no information on how to achieve this effect. Right now, I have this:
// create the particle system
let exp = SCNParticleSystem()
exp.loops = true
exp.particleMass = 5
exp.birthRate = 10000
exp.emissionDuration = 10
exp.emitterShape = SCNTorus(ringRadius: 5, pipeRadius: 1)
exp.particleLifeSpan = 15
exp.particleVelocity = 2
exp.particleColor = UIColor.white
exp.isAffectedByPhysicsFields = true
scene.addParticleSystem(exp, transform: SCNMatrix4MakeRotation(0, 0, 0, 0))
// create the field
let field = SCNPhysicsField.vortex()
field.strength = -5
field.direction = SCNVector3(x: 0, y: 1, z: 0)
let fieldNode = SCNNode()
fieldNode.physicsField = field
scene.rootNode.addChildNode(fieldNode)
This creates this effect:
Where I am looking down at the particles rotating clockwise with a really big radius outwards. It looks nothing like a tornato effect. How can I create this effect?
You say tornato, I say tornado, let’s call the whole thing off...
The SceneKit WWDC 2014 demo/slides is a sample code project, so you can see for yourself how they made any of the effects you see therein. In this case, it looks like the “vortex” demo isn’t actually using the vortexField API, but instead the custom field API that lets you supply your own math in an evaluator block. (See the link for the code in that block.)
You might be able to get similar behavior without a custom field by combining a vortex (causes rotation only) with radial gravity (attracts inward) with linear gravity (attracts downward), or some other combination (possibly something involving electric charge). But you’d probably have to experiment with tweaking the parameters quite a bit.
If anyone is still interested in this topic - here is a Swift 5 implementation of that legendary tornado effect.
Here is an example function that will create your tornado.
func addTornadoPhysicsField() {
// Tornado Particles Field Example
guard let tornadoSystem = SCNParticleSystem(named: "tornado.scnp", inDirectory: nil) else { return }
let emitterGeometry = SCNTorus(ringRadius: 1.0, pipeRadius: 0.2)
emitterGeometry.firstMaterial?.transparency = 0.0
let fieldAndParticleNode = SCNNode(geometry: emitterGeometry)
fieldAndParticleNode.position = SCNVector3(0.0, 0.0, -20.0)
tornadoSystem.emitterShape = emitterGeometry
fieldAndParticleNode.addParticleSystem(tornadoSystem)
yourScene.rootNode.addChildNode(fieldAndParticleNode)
// Tornado
let worldOrigin = SCNVector3Make(fieldAndParticleNode.worldTransform.m41,
fieldAndParticleNode.worldTransform.m42,
fieldAndParticleNode.worldTransform.m43)
let worldAxis = simd_float3(0.0, 1.0, 0.0) // i.Ex. the Y axis
// Custom Field (Tornado)
let customVortexField = SCNPhysicsField.customField(evaluationBlock: { position, velocity, mass, charge, time in
let l = simd_float3(worldOrigin.x - position.x, 1.0, worldOrigin.z - position.z)
let t = simd_cross(worldAxis, l)
let d2: Float = l.x * l.x + l.z * l.z
let vs: Float = 27 / sqrt(d2) // diameter, the bigger the value the wider it becomes (Apple Default = 20)
let fy: Float = 1.0 - Float((min(1.0, (position.y / 240.0)))) // rotations, a higher value means more turn arounds (more screwed, Apple Default = 15.0))
return SCNVector3Make(t.x * vs + l.x * 10 * fy, 0, t.z * vs + l.z * 10 * fy)
})
customVortexField.halfExtent = SCNVector3Make(100, 100, 100)
fieldAndParticleNode.physicsField = customVortexField // Attach the Field
}
Additional Configuration Options:
Finally all this can result in something like that:
Note: if you would like to move your static tornado almost like a real tornado, you will have to find a way to re-apply the physics field for each rendererd frame. If you don't, the world origin used in the evaluation block will not move and it will distort your tornado.
Note: You can also split the particle/field node into two different nodes that moves independently from each other. Constrain the field node to the position of the particle node and play around with the influence factor (still need to re-apply the field each frame)
For more information on Custom Fields check out here.
So here is the code:
local prt = Instance.new('Part',game.Workspace)
prt.Color = Color3.new(248, 248, 248)
prt.Size = Vector3.new(0.167, 5, 5)
prt.Rotation = Vector3.new(0, 0, math.rad(90))
prt.Anchored = true
prt.CFrame = CFrame.new(Vector3.new(19.1, 618.59, 116.85))
prt.Shape = "Cylinder"
what i want it to do is create a new part that is shaped like a cylinder, i want it to be a flat cylinder but it does the exact oppisite, it is standing up, i have tried many things.
The CFrame is setting the Rotation to 0,0,0. This is because you're doing CFrame.new() before prt.Rotation. If you did CFrame.new(Vector3.new(19.1,618.59,116.85)) * CFrame.Angles(0, 0, math.rad(90)), this would work and you can remove the "prt.Rotation" part.
I want to create an eyeball that follows the user. In this sense, the eye should follow the position of the user but should only be able to move within certain bounds (The eye socket). The code I wrote below works, but its very choppy.
if(dist <= socketRadius - self.aEye.size.width/2.2){
lastPosition = self.aEye.position
self.aEye.physicsBody?.velocity = CGVector(dx:theVec.dx * eyeMoveSpeed, dy:theVec.dy * eyeMoveSpeed)
}
else{
let toCenterVector = normalizeVector( CGVector(dx:(self.socket.position.x - self.aEye.position.x), dy:(self.socket.position.y - self.aEye.position.y)*3 ))
self.aEye.physicsBody?.velocity = toCenterVector
print(toCenterVector)
print("Out")
}
(dist is the distance from the eyeball to the eyesocket center)
Is there a way to have a smooth flow of the eyeball around its socket to follow the user's position?
You can use SKConstraints to achieve this. Something like:
let rangeToCenterSprite = SKRange(lowerLimit: 80, upperLimit: 90)
var distanceConstraint: SKConstraint
distanceConstraint = SKConstraint.distance(rangeToCenterSprite, toNode: SpriteNodeInEyeCenter)
EyeBallSprite.constraints = [distanceConstraint]
I was reading some tutorial of One simulator. I got one syntax that is
group.nodeLocation = 100,100
As far as I know a group can have multiple nodes. Therefore, I am not clear what does it mean by group.nodeLocation. Which node location we are fixing by using this command.
Thanks,
It depends on which kind of movement models you use.
Setting group.nodeLocation is required for StationaryMovement, but for other dynamic movement modes (e.g., RandomWaypoint) is meaningless.
If you want to set multiple nodes N with different location, you should separate it into N groups.
In speaking of adding static nodes in bulk, use MapRouterMovement to simulate it. The static node can be regarded as the initioal coordination equals the destination coordination. For instance, 5 static nodes are defined as:
LINESTRING (100 100, 100.0 100.0)
LINESTRING (200 200, 200.0 200.0)
LINESTRING (300 300, 300.0 300.0)
LINESTRING (400 400, 400.0 400.0)
LINESTRING (500 500, 500.0 500.0)
And the setting file like:
Group4.groupID = b
Group4.movementModel = MapRouteMovement #MapRouteMovement
Group4.routeFile = path/routFile.wkt #routeFile
Group4.routeType = 2
Group4.nrofHosts = 5
Group4.waitTime = 0, 0
Group4.speed = 0, 0
BTW, don't forget to group the above coordinations as a map file, seeing below:
#settings.txt
MapBasedMovement.nrofMapFiles = 1
MapBasedMovement.mapFile1 = path/mapFile.wkt
#mapFile.wkt
LINESTRING (100 100, 200.0 200.0, 300 300, 400 400, 500.0 500.0)
This is a continuous question of https://stackoverflow.com/a/21074207/3269910
the solution seems fine c0.0.851.315
but the c0.0 values are pointing to 0x0 position of the images
what i want is the image with offset_y . if an offset_y: 20,
ie, i want the same size and part of image, what i am seeing in my page timeline in a api call.
Is it possible to do this ?
Note: if i change c0.0 the zero value to some other then it is pointing to pixels but offset_y is % i think.
Thanks for your help.
I had discussion with Facebook Platform Team;
They are not ready to share the manual calculation to us.
and yes, it is possible to calculate value of c0.XXXX manually using your API offset_y value.
Here is my PHP code.
$fb_page_cover_json = json_decode( file_get_contents( 'https://graph.facebook.com/11111111?fields=cover'));
$fb_cover_image_url = $fb_page_cover_json->cover->source;
$image_info = getimagesize($fb_cover_image_url);
$image_width = $image_info[0];
$image_height = $image_info[1];
echo getTop($fb_page_cover_json->cover->offset_y,$image_width,$image_height);
function getTop($offset_y,$image_width,$image_height) {
$cover_w = 851;
$cover_h = 315;
$img_w = $image_width;
$img_h = $image_height;
$real_img_h = ($cover_w * $img_h / $img_w) - $cover_h;
$result = ($real_img_h * $offset_y / 100 * -1);
return floor($result);
}
The method getTop will return the c0.XXX value.
Hope this helps some one.