I use Glut to make a simple animation. In the main function, glutTimerFunc(TIMERMSECS, animate, 0) is called. The two pieces of codes generate the same graphic.
const int TIMERMSECS = 20;
float animation_time = 0;
const float animation_step = .5;
Method 1:
void animate(int t){
float time_elapsed = TIMERMSECS/1000.0;
float current_step = animation_step* time_elapsed;
glutTimerFunc(TIMERMSECS, animate, 0);
if(current_step < animation_step*2)
animation_time += current_step;
glutPostRedisplay();
}
Method 2:
void animate(int t){
float time_elapsed = TIMERMSECS/1000.0;
float current_step = animation_step* time_elapsed;
if(current_step < animation_step*2)
animation_time += current_step;
glutPostRedisplay();
glutTimerFunc(TIMERMSECS, animate, 0);
}
The only difference between them is the position of glutTimerFunc. For Method 1, it looks like a recursive that will never reach the end of animate()function. But why does that still work?
glutTimerFunc will not immediately call the timer function under any circumstances. Even if the time is 0. It always waits for the message processing loop, and even then it will only call the requested function when all other message processing has completed. That way, important messages like "repaint window" and "resize window" still get processed.
In general, you should not rely on the timer function being particularly accurate.
Related
i'm trying to make this interaction with keyboard for movement using some sprites and i got stuck with two situations.
1) The character movement is not going acording to the animation itself (it only begin moving after one second or so while it's already being animated). What i really want it to do is, to move without a "initial acceleration feeling" that i get because of this problem
2) I can't think of a way to make the character face the position it should be facing when the key is released. I'll post the code here, but since it need images to work correctly and is not so small i made a skecth available at this link if you want to check it out: https://www.openprocessing.org/sketch/439572
PImage[] reverseRun = new PImage [16];
PImage[] zeroArray = new PImage [16];
void setup(){
size(800,600);
//Right Facing
for(int i = 0; i < zeroArray.length; i++){
zeroArray[i] = loadImage (i + ".png");
zeroArray[i].resize(155,155);
}
//Left Facing
for( int z = 0; z < reverseRun.length; z++){
reverseRun[z] = loadImage ( "mirror" + z + ".png");
reverseRun[z].resize(155,155);
}
}
void draw(){
frameRate(15);
background(255);
imageMode(CENTER);
if(x > width+10){
x = 0;
} else if (x < - 10){
x = width;}
if (i >= zeroArray.length){
i = 3;} //looping to generate constant motiion
if ( z >= reverseRun.length){
z = 3;} //looping to generate constant motiion
if (isRight) {
image(zeroArray[i], x, 300);
i++;
} //going through the images at the array
else if (isLeft) {
image(reverseRun[z],x,300);
z++;
} going through the images at the array
else if(!isRight){
image(zeroArray[i], x, 300);
i = 0; } //"stoped" sprite
}
}
//movement
float x = 300;
float y = 300;
float i = 0;
float z = 0;
float speed = 25;
boolean isLeft, isRight, isUp, isDown;
void keyPressed() {
setMove(keyCode, true);
if (isLeft ){
x -= speed;
}
if(isRight){
x += speed;
}
}
void keyReleased() {
setMove(keyCode, false);
}
boolean setMove(int k, boolean b) {
switch (k) {
case UP:
return isUp = b;
case DOWN:
return isDown = b;
case LEFT:
return isLeft = b;
case RIGHT:
return isRight = b;
default:
return b; }
}
The movement problem is caused by your operating system setting a delay between key presses. Try this out by going to a text editor and holding down a key. You'll notice that a character shows up immediately, followed by a delay, followed by the character repeating until you release the key.
That delay is also happening between calls to the keyPressed() function. And since you're moving the character (by modifying the x variable) inside the keyPressed() function, you're seeing a delay in the movement.
The solution to this problem is to check which key is pressed instead of relying solely on the keyPressed() function. You could use the keyCode variable inside the draw() function, or you could keep track of which key is pressed using a set of boolean variables.
Note that you're actually already doing that with the isLeft and isRight variables. But you're only checking them in the keyPressed() function, which defeats the purpose of them because of the problem I outlined above.
In other words, move this block from the keyPressed() function so it's inside the draw() function instead:
if (isLeft ){
x -= speed;
}
if(isRight){
x += speed;
}
As for knowing which way to face when the character is not moving, you could do that using another boolean value that keeps track of which direction you're facing.
Side note: you should really try to properly indent your code, as right now it's pretty hard to read.
Shameless self-promotion: I wrote a tutorial on user input in Processing available here.
I'm new to processing and trying to make a very simple program where i have an arduino that produces a seriel input (according to an analogue read value). The idea is a Processing window will open with a block color shown for 30 seconds. In this time all the readings from the arduino will be summed and averaged - creating an average for that color.
After 30 seconds the colour will change and a new average (for the next color) will start being calculated. This is the code i have started to write (for now focusing on just one 30 second period of green).
I realise there are likely problems with the reading/summing and averaging (i havent researched these yet so i'll put that to one side) - but my main question is why isn't the background green? When i run this program i expect the background to be green for 30 seconds - where as what happens is it is white for 30 seconds then changes to green. Can't figure out why! Thanks for any help!
import processing.serial.*;
Serial myPort;
float gsrAverage;
float greenAverage;
int gsrValue;
int greenTotal = 0;
int greenCount = 1;
int timeSinceStart = 0;
int timeAtStart;
int count=0;
color green = color(118,236,0);
void setup () {
size(900, 450);
// List all the available serial ports
//println(Serial.list());
myPort = new Serial(this, Serial.list()[0], 9600);
}
void draw () {
while (timeSinceStart < 30000) {
background(green);
greenTotal = greenTotal + gsrValue;
greenCount = greenCount + 1;
delay(500);
timeSinceStart = millis()-timeAtStart;
//println(timeSinceStart); for de bugging
}
greenAverage = greenTotal/greenCount;
//println(greenAverage); for de bugging
}
void serialEvent (Serial myPort) {
int inByte=myPort.read();
//0-255
gsrValue=inByte;
}
What I like to do for timers, is use IF statements and use millis() or a constantly updated variable 'm' right inside the condition:
int timeSinceStart;
int m;
void setup(){
timeSinceStart = millis(); // initialize here so it only happens once
}
void draw(){
m = millis(); // constantly update the variable
if(timeSinceStart + 30000 < m){
greenAverage = greenTotal/greenCount; // or whatever is outside while loop
timeSinceStart = millis();
}
//Anything that went inside the while loop can go here, or above the IF
}
This makes it so around every 30 seconds, the background will change once, and you just re-update the timeSinceStart variable in there too. This way, it will only update when you want it to update and not constantly update and break the code.
I tend not to use while loops in processing as they usually cause headaches. Hope my example helps.
May have found a way round this using an IF statement. I perhaps looked over the fact the draw function is itself a loop, so i was able to use a variation of
if (timeSinceStart < 5000) {
background(green);
}
within draw.
When dealing with timed events in Processing you should not use while loops inside the draw() function. The draw() function itself is a while loop which updates the "screen" each frame.
So, what you should do is create a timer and let it do a switch for you inside the draw() function. In your case, if you want to start with a green screen, you do that in the setup() function, and then create a method for altering according to a timer in your draw() function.
This is a suggestion on how you could solve your particular problem. Just change the cycle variable according to your need. In your case it would be 30000.
boolean isGreen = true;
int startTime = 0;
int lastTime = 0;
int cycle = 1000; //the cycle you need
void setup() {
size(200, 200);
background(0, 255, 0); //green
}
void draw() {
startTime = millis();
if (startTime > lastTime + cycle) {
if (isGreen) {
background(255); //white
isGreen = !isGreen;
} else {
background(0, 255, 0); //green
isGreen = !isGreen;
}
lastTime = millis();
}
}
I have a separate stack in my program with this timer vector attached. When called, the stack pops an element out and the timer keeps track of how long it is out via user input. When the time reaches 0, the element is put back into the stack. I wanted to work through multiple timers so I tried to put them all into a vector and have them all decrement by one time unit when a function is called. Not totally clear on how vectors work so I do not know how to decrement all of a vector's values.
int wait(vector<int> &x){
std::vector<int>::iterator itr;
for(itr = x.begin(); itr < x.end(); itr++)
{ //psuedocode
//x[itr]--;
}
}
I just want to make sure I'm going in the right direction.
Here is how you can decrement all the values in the vector
int wait(vector<int> &x){
for(std::vector<int>::iterator itr = x.begin(); itr != x.end(); itr++)
{
(*itr)--;
}
}
or using C++11
int wait(vector<int> x){
for (int& i : x )
i--;
}
To decrease the value pointed by the iterator in the code, you can do -
for(itr = x.begin(); itr < x.end(); itr++)
{ //psuedocode
(*itr)--;
}
*itr returns the value being pointed by the iterator.
To detect 3D world coordinates through the 2D screen coordinates of the iOS, is there any other possible way besides the gluUnProject port?
I've been fiddling around with this days on end now, and I can't seemingly get the hang of it.
-(void)receivePoint:(CGPoint)loke
{
GLfloat projectionF[16];
GLfloat modelViewF[16];
GLint viewportI[4];
glGetFloatv(GL_MODELVIEW_MATRIX, modelViewF);
glGetFloatv(GL_PROJECTION_MATRIX, projectionF);
glGetIntegerv(GL_VIEWPORT, viewportI);
loke.y = (float) viewportI[3] - loke.y;
float nearPlanex, nearPlaney, nearPlanez, farPlanex, farPlaney, farPlanez;
gluUnProject(loke.x, loke.y, 0, modelViewF, projectionF, viewportI, &nearPlanex, &nearPlaney, &nearPlanez);
gluUnProject(loke.x, loke.y, 1, modelViewF, projectionF, viewportI, &farPlanex, &farPlaney, &farPlanez);
float rayx = farPlanex - nearPlanex;
float rayy = farPlaney - nearPlaney;
float rayz = farPlanez - nearPlanez;
float rayLength = sqrtf((rayx*rayx)+(rayy*rayy)+(rayz*rayz));
//normalizing rayVector
rayx /= rayLength;
rayy /= rayLength;
rayz /= rayLength;
float collisionPointx, collisionPointy, collisionPointz;
for (int i = 0; i < 50; i++)
{
collisionPointx = rayx * rayLength/i*50;
collisionPointy = rayy * rayLength/i*50;
collisionPointz = rayz * rayLength/i*50;
}
}
There's a good chunk of my code. Yeah, I could have easily used a struct but I was too mentally fat to do it at the time. That's something I could go back and fix later.
Anywho, the point is that when I output to the debugger using NSLog after I use gluUnProject, the nearplane's and farplane's don't relay results even close to accurate. In fact, they both relay the exact same results, not to mention, the first click always reproduces x, y, & z being all equal to "nan."
Am I skipping over something extraordinarily important here?
There is no gluUnProject function in ES2.0, what is this port that you are using? Also there is no GL_MODELVIEW_MATRIX or GL_PROJECTION_MATRIX, which is most likely your problem.
I'm trying to create a function that changes a label's text. I want it in a "Wheel of Fortune" style where the text changes really quickly at first but slows down over time, then stops at the final text. I have the text as strings in an array.
I'm guessing I would need an exponential function to do this but maths is not my strong point. Currently I'm trying:
- (void)timer {
float time = 0.5;
float increase = 0.05;
for(int x = 0; x < 100; x++) {
sleep(time);
time = time + increase;
NSLog(#"%f", time); //Log to show time of each iteration
}
}
I don't need help linking it up with labels etc., I just need help to get the timing right.