Develop Reference

Mapping Xamarin (Android) touch event coords to webview pixels

I have a webview in an android xamarin application. When a user swipes the screen left or right I need to check if the swipe happened over a specific element. To handle the swipe logic I am using this code:
float startY = 0;
private void BindTouchEvents() {
float startX = 0;
float webViewWidth = 0;
webView.Touch += (sender, e) => {
if (e.Event.Action == Android.Views.MotionEventActions.Down)
{
webViewWidth = webView.Width;
startX = e.Event.GetX();
startY = e.Event.RawY; //I've tried both GetY and RawY here
}
if (e.Event.Action == Android.Views.MotionEventActions.Up)
{
float movement = e.Event.GetX() - startX;
float offset = webViewWidth / 2;
if (Math.Abs(movement) > offset)
{
if (movement < 0)
{
client.NotifyTouch(webView, e.Event.GetX(), startY, "SwipeLeft");
}
else
{
client.NotifyTouch(webView, e.Event.GetX(), startY, "SwipeRight");
}
}
}
e.Handled = false;
};
}
The client.NotifyTouch call invokes some javascript in the webview which determines if the swipe event occured over a specific element. If it did, it toggles that elements visibility to hidden. The element is in a fixed position at 0,0 and is 64px in height, so this logic is quite simple:
$scope.$on('received-touch-event', function (e, args) {
if ($scope.showLaunchNavBar && (args.event === "SwipeLeft" || args.event === "SwipeRight") && args.y > 0 && args.y < 64) {
$scope.showLaunchNav(false);
};
});
The problem is that the startY value doesn't seem to translate evenly to webview pixels. For example, if I try to swipe roughly at 0,0 and inspect the starting Y position it's above 100, if I try to swipe roughly at 0,64, the starting Y position ends up being above 400. I need to figure how to translate these values into WebView pixels. I'm assuming it has something to do with the pixel density on my device, but I'm not sure how to go about translating the values into "web-pixels" in a generic way that would work across all devices.
I've tried googling, reading docs and searching on here for an answer but can't seem to find what I'm looking for. Probably not using right terminology. Any help is appreciated.

I believe I figured out, here's the solution:
public static float ConvertDpToPixel(float dp, Context context)
{
return dp / ((float)context.Resources.DisplayMetrics.DensityDpi / (float)DisplayMetricsDensity.Default);
}

Sprite bouncing off the sides - bottom & right side work but not top and left

i'm trying to create a wrap around method to make a sprite bounce of each side of the screen. I've got the bottom and right side working but can't seem to figure out why it won't off the top or the left. Any help would be much appreciated. Here is my code:
public void wrapAround(){
wrapAround = true;
//Code to wrap around
if (x < 0) x = x + gameView.getWidth(); //increment x whilst not off screen
if (x >= gameView.getWidth()){ //if gone of the right sides of screen
xSpeed = (xSpeed * -1);
}
if (x <= gameView.getWidth())
{
xSpeed = (xSpeed * -1);
}
if (y < 0) y = y + gameView.getHeight();//increment y whilst not off screen
if (y >= gameView.getHeight()){//if gone of the bottom of screen
ySpeed = (ySpeed * -1);
}
if (y <= gameView.getHeight())
{
ySpeed = (ySpeed * -1);
}

Your question needs a lot of clarification.
if (x < 0) x = x + gameView.getWidth(); //this code executes only when x IS off screen on the left side, which means you want to move it to the right size. No bouncing is implied here.
The following reverses the velocity of the sprite if it is off the screen on the right side, but if the function wrap around is called again right afterwards, the velocity would reverse again making it wiggle back and forth when hitting left or bottom wall.
if (x >= gameView.getWidth()){ //if gone of the right sides of screen
xSpeed = (xSpeed * -1);
}
if (x <= gameView.getWidth())
{
xSpeed = (xSpeed * -1);
}
I have no idea what you're actually trying to achieve, because half your code attempts to wrap an item around, while the other half attempts to make it bounce.

Using Android accelerometer y axis falls through terrain - Unity3D

This works much better, thank you. However, it still does not work very well. While I don't go completely through the terrain, the FP controller seems to hover just below the terrain. Adding a +10 helps, but there is another strange issue:
I have the camera set up as a child of the FP controller, at 0,0,0. When the game begins to run, the Y value in the transform of the controller window goes steadily down, in minus numbers, while the camera Y value goes steadily up, in the positive direction. The Y values are mirrored. Any ideas of what is going on?
void Update () {
moveX = Input.acceleration.x * 1;
moveY = Input.acceleration.y * 1;
moveZ = (1+ (Input.acceleration.z));
transform.Translate (0, 0, 0); //transform.translate Moves the transform in the direction and distance of translation
temp = transform.position; //temp = the position of the transform in world space. World Space: the absolute XYZ coordinates of all objects
temp.y = terrainY; //y component of Vector3 (float)
transform.position = temp; //put the position of the transform in world space back into temp
terrainY = Terrain.activeTerrain.SampleHeight(temp); //Sample.height Samples the height at the given position defined in world space
temp2 = transform.position.y; //this shows transform.position.y axis is the same as terrainY, but not the same value as shown in the inspector
if (moveZ >= 0.055 && moveZ >= -0.1) {
zeroZFlag = 1;
if(moveZ >= 0.041){
moveZ = moveZ*10; //multiply by 10 to make it faster when going forward
if (moveY >= 0) {
transform.Translate (moveX,terrainY + 10,moveZ);
//transform.translate needs to be three floats. So the middle one needs to be the y value of the top of the terrain
}
if (moveY < 0){
transform.Translate (moveX,terrainY,-moveZ);
}
}
I have added to my code as suggested but am still having trouble getting the first person controller to stay on the same y-value as the terrain. In the following iteration of code, the First person y value leaves the world entirely and goes up forever.
My code uses
`transform.Translate (moveX,terrainY,moveZ);
to move the FP controller around, where moveX and moveY are acceleration values and terrainY theoretically should be the actual value of the Y-axis as shown in the transform box.
I think that the first issue is that I am mixing acceleration values (X,Z) with a terrain transform for Y, so different meaning to the values.
BTW X and Z axis move very well with the accelerometer with this code, but I will change everything if necessary!
I am not sure what kind of float value operation translate.transform does. The manual states that it returns in the space.world, but does it move by the number of units or position?
Here is my new code, and thank you in advance for help:
public float terrainY;
// y axis falls through terrain
// travels through walls even though collider is set
void LateUpdate (){
//terrainY = Terrain.activeTerrain.SampleHeight (transform.position);
}
void Update () {
moveX = Input.acceleration.x * 1;
moveY = Input.acceleration.y * 1;
moveZ = (1+ (Input.acceleration.z));
transform.Translate (0, 0, 0);
terrainY = Terrain.activeTerrain.SampleHeight (transform.position);
if (moveZ >= 0.055 && moveZ >= -0.1) {
zeroZFlag = 1;
if(moveZ >= 0.041){
moveZ = moveZ*10; //multiply by 10 to make it faster when going forward
if (moveY >= 0) {
transform.Translate (moveX,terrainY,moveZ);
//transform.translate needs to be three floats. so the middle one needs to be the y value of the top of the terrain
}
if (moveY < 0){
transform.Translate (moveX,terrainY,-moveZ);
}
My code causes me to go through and under my terrrain in Unity 3D because the y axis is always zero. In this world, x-axis is left/right and z is depth. Y axis is up/down and shold follow the mountains, hills, valleys in the terrain. However, it just goes through, at 0 height.
Does anyone know what variable/class should be in the y-axis spot instead of the "0" I have there? Thanks in advance!
public class Movement2 : MonoBehaviour {
public float moveX = Input.acceleration.x;
public float moveY = Input.acceleration.y;
public float moveZ = Input.acceleration.z;
public float Speed = 20.0f;
public int zeroZFlag;
void Update () {
moveX = Input.acceleration.x * 1;
moveY = Input.acceleration.y * 1;;
//moveZ = Mathf.Abs(1+ (Input.acceleration.z) * 20);
moveZ = (1+ (Input.acceleration.z));
transform.Translate (0, 0, 0);
if (moveZ >= 0.055 && moveZ >= -0.1) { zeroZFlag = 1;
if (moveY >= 0) {
transform.Translate (moveX,0,moveZ);
}
if (moveY < 0){
transform.Translate (moveX,0,-moveZ);
}
else {
zeroZFlag = 0;
}
}

Try using Terrain.SampleHeight(), it returns the height of the terrain with a given X and Z coordinate. Update its Y position to the height of the terrain every Update().
Reference: http://docs.unity3d.com/ScriptReference/Terrain.SampleHeight.html.
EDIT 1:
The reason your FP controller always goes up forever is because you keep translating it with a Y value.
transform.Translate(moveX, terrainY, moveZ)
// this way you keep adding terrainY value to the Y position
// thus it always goes up and will never end
While you need your FP controller to be constantly the same Y position with the terrain. You should instead modify the position of Y directly.
Vector3 temp = transform.position;
temp.y = terrainY;
transform.position = temp;
EDIT 2:
I try my best to help you see through your code:
void Update () {
moveX = Input.acceleration.x * 1;
moveY = Input.acceleration.y * 1;
moveZ = (1+ (Input.acceleration.z));
transform.Translate (0, 0, 0); // why do you need this? this basically does nothing
// you should get terrain height first to be used as temp.y below
terrainY = Terrain.activeTerrain.SampleHeight(transform.position);
temp = transform.position;
temp.y = terrainY + 10; // you said +10 helped, so I put it here
transform.position = temp;
if (moveZ >= 0.055 && moveZ >= -0.1) {
zeroZFlag = 1;
if(moveZ >= 0.041){
moveZ = moveZ*10;
if (moveY >= 0) {
// here I think you shouldn't move the Y anywhere,
// because you've updated position of Y in every update frame
// so you only need to move X and Z due to device tilt
transform.Translate (moveX,0,moveZ);
}
if (moveY < 0){
transform.Translate (moveX,0,-moveZ);
}
}

This also works:
using UnityEngine;
using System.Collections;
[RequireComponent(typeof(CharacterController))]
public class Movement6 : MonoBehaviour {
public float speed = 30.0f;
public float moveX = Input.acceleration.x;
public float moveY = Input.acceleration.y;
public float moveZ = Input.acceleration.z;
void Update() {
moveX = Input.acceleration.x * 1;
moveY = Input.acceleration.y * 1;
moveZ = (1+ (Input.acceleration.z));
CharacterController controller = GetComponent<CharacterController>();
Vector3 forward = transform.TransformDirection(moveX,0,moveZ);
controller.SimpleMove (forward * speed);
}
}

Smooth fly movement like flappy bird or jet pack joy ride with gravity and Accelaration

I am developing a simple game in which a character fly when you tap/click the screen. keep tapping the character will fly (some what similar to flappy bird and jet pack). However the movement is not smooth at all, as of jet pack.
Here is sample of my code.
Varaible Initilization
maxSpeedLimit = spriteHeight/10;
speed = maxSpeedLimit/2; //half of the max speed
touch event
public void onTapOrClick(int action) {
if (action == UP) {
sprite.up= true;
}
else {
sprite.up = false;
}
}
Sprite update called from game loop
public void update() {
if (up) {
y -= speed; //fly up
}
else {
y += speed;// fly down
}
if (speed < maxSpeedLimit) {
speed++; // May be cheep way to add **velocity/acceleration**
}
}
I think speed++ is not a smooth way to increase the speed, I am not sure but may be adding some time related variable to increment may improve it, moreover adding a gravity will make it more realistic but i have no idea how to do it, I have read few blogs, first thing I am not able to search with the correct keyword, and second thing is they are so hard understand because they contains platform related codes. Please help.
I am making this game in android, but code in any language is accepted (HTML5, javascript, Android, Flash or any).
Q: How to add acceleration and gravity to an object (sprite) which fly when user tap or click and fall on release?
Something similar to jet pack joyride (only up and down movement)
UPDATED
After #scottt advise I have implemented the dY += gravity + flapp I can feel now gravity, however there are 2 issues.
My screen height is 480, and sprite immediately touch upper(y=0) and lower(y=480) boundary, becuase i think it keep increasing the speed of the sprite.
when it touches the ground, it seems very havey and take much time to lift the sprite up in the air.
Some how there should be some limit to dY which is constantly being added to y location.
Here is update code.
int downSpeed = 1;
int upSpeed = -2;
int dy = 0;
private void update() {
if (flapping) {
upSpeed = -2; //if flying speed
}
else {
upSpeed = 0;
}
dy += downSpeed + upSpeed;
if (dy < -10) {
dy = -10; //limit for rise speed
}
else if (dy > 8) {
dy = 8; //limit for gravity
}
y += dy; // add value in y location
if (y > GAME_HEIGHT - sprite.getHeight()) {
y = GAME_HEIGHT - sprite.getHeight(); // reset y, if touch ground
dy = 0; //reset speed, otherwise it make it very heavy to rise
}
else if ( y < 0) {
y = 0; //reset y if touch upper limit
dy = 0; //reset speed, otherwise take much time to fall (as it would be in negative)
}
}

Gravity is just a downward acceleration. An acceleration is in turn just a change in velocity (directed speed). For the following discussion, I make the following assumptions to keep things simpler:
your horizontal speed is constant
input tapping is called 'flapping'
gravity behaves normally
simplistic, rather than a scientific approach/verbiage is OK for our purposes
For each pass through the update loop, all of the various accelerations must be summed and the total added to the current speed. In your situation, there are 2 possible accelerations, gravity and possibly flapping. Gravity is constant and is a negative value (is works downward), while flapping only occurs during tapping as is positive (upwards).
Let's set gravity to -10 pixels per loop, tapping to be +25 pixels per loop, and initial height to 500. Some initial definitions are:
static final int gravity = -10; // constant downward acceleration
static final int flapping = 25; // upward acceleration whenever isFlapping is true
Boolean isFlapping = false; // Is the bird flapping
int dY = 0; // current vertical speed
y = 500; // current vertical position
Each time through the loop, without flapping, the speed calculation would be:
dY += gravity + flapping;
So the first time through, the speed calculation would be dY = 0 + (-10) + 0 = -10. The second time, dy = -10 + (-10) + 0 = -20. The 5th time, dy = -40 + (-10) = -50. Each time through, the downward speed is 10 more than the time before.
The height is simple. Each time through, the height changes by the amount of vertical acceleration. So:
y += dY;
So the first time through, the height would be y = 500 + (-10) = 490. The second time, y = 490 + (-20) = 470. And the 5th time, y = 400 + (-50) = 350. Because the rate of falling increases each time through, the bird will plummet faster and faster until splat!
That's where flapping comes in. Each time through the loop where flapping is occurring, a +25 will be applied to the dY calculation. So lets assume the bird starts flapping in 6th iteration. The dy calculation would be dy = -50 + (-10) + 25 = -35 and the height would be y = 350 + (-35) = 315. The next time through would give dy = -35 + (-10) + 25 = -20 and the height would be y = 350 + (-20) = 295. Still falling, but more slowly. The time after: that dy = -20 + (-10) + 25 = -5 and y = 295 + (-5) = 290. The time after that finally shows a gain in height: dy = -5 + (-10) + 25 = 10 and y = 290 + 10 = 300.
All that said, you'll definitely need to play with the numbers until you get a satisfying result.
TLDR: You don't want to change the height directly using gravity and flapping. Instead you want to use gravity and flapping to calculate the speed for each iteration and then use that to adjust the height.

How to write an intersects for Shapes in android

I have an written an Object called Shape which has a Point representing the topLeftCorner and a Dimension with represents its width and height.
To get the topRightCorner I can simply add the width to the topLeftPoint.x. I use to rotate them on a certain degree around their center. The problem after the rotation is, that my intersects(Shape) method fails, because it does not honor the rotation of the Shapes. The rotation will be the same for each Shape. My current implementation looks like this inside my Shape Object:
public boolean intersects(Shape s){
// functions returning a Point of shape s
return intersects(s.topLeft())
|| intersects(s.topRight())
|| intersects(s.bottomLeft())
|| intersects(s.bottomRight())
|| intersects(s.leftCenter())
|| intersects(s.rightCenter())
|| intersects(s.center());
}
public boolean intersects(Point p){
return p.x >= leftX()
&& p.x <= rightX()
&& p.y >= topY()
&& p.y <= bottomY();
}
Basically I need functions like rotatedLeftX() or rotatedTopRight() to work properly. Also for that calculation I think it doesn't matter when the topLeft point before a rotation of ie 90 will turn into topRight...
I already read this and this Question here, but do not understand it fully.

I modified an algorithm from Stackoverflow to do what you are indicating with rectangles for a battleship game I wrote. Here is the code:
private boolean overlaid(int [][][] shps, int curr)
{
for (int i = curr-1; i>=0; --i)
{
// From: http://stackoverflow.com/questions/306316/determine-if-two-rectangles-overlap-each-other/306332#306332
// if (RectA.X1 < RectB.X2 && RectA.X2 > RectB.X1 &&
// RectA.Y1 < RectB.Y2 && RectA.Y2 > RectB.Y1)
if (shps[curr][0][1] <= shps[i][1][1] &&
shps[curr][1][1] >= shps[i][0][1] &&
shps[curr][0][0] <= shps[i][1][0] &&
shps[curr][1][0] >= shps[i][0][0])
return true;
}
return false;
}
private int [][][] shps = { {{-1,-1},{-1,-1}},
{{-1,-1},{-1,-1}},
{{-1,-1},{-1,-1}} };
The shps parameter is just a matrix indicating the location of the top-left and bottom-right corners of each rectangle using {x0,y0}, {x1,y1}. For example, shps[curr][0][1] == the current shp's y0. For my purposes, I had to use <= and >=. Also, you have to be mindful of the reverse of y if you are using screen coordinates versus Cartesian coordinates. Also DeMorgan's Law if you want to use NOT overlaid.

I have a solution:
lets assume I want to calculate the rotation (90 degrees) of a Shape with x =1, y=1 (topLeft Point) and a width of 4 and a height of 6 around its center (3, 4) == (x1, y2)
rotatedX = x1 + cos(q) * (x - x1) - sin(q) * (y - y1)
rotatedY = y1 + sin(q) * (x - x1) + cos(q) * (y - y1)
in this case:
rotatedX = 3 + cos(90) * (1 - 3) - sin(90) * (1 - 4)
rotatedY = 4 + sin(90) * (1 - 3) + cos(90) * (1 - 4)
this is for a rotation in a cartesian-plane (where positive rotation values means rotation counter-clockwise)
So if you wanna aply a rotation of 90 degrees CLOCKWISE you just have to multiply rotation with -1;