No member named "centerX" or "centerY" error when trying to get object position from Vision Sensor

Programming Support VEXcode Pro V5 Text Tech Support
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#1

I have been trying to write a program that gives me the position of an object detected by the Vision Sensor however when using an instruction like
printf("%.2f", Vision10.objects.centerY);
however I get the error
“No member named centerY in 'vex::safearray<vex::vision::object, 16>”
Any help is appreciated.

#2

vision::objects is an array that contains the largest objects. What you are probably looking for is vision::largestObject.

printf("%.2f", Vision10.largestObject.centerY);

Another method of doing this is to access the first element of the array

printf("%.2f", Vision10.objects[0].centerY);
6 Likes
#3

Thank you, the code you gave me did not work until I tweaked it to make the output a double as shown below
printf("%.2f", (double)Vision10.largestObject.centerY);
and another instruction in the program has shown that the sensor is working as intended however the location text output rarely occurs and when it does, it is random.

#4

Could you share more of the code surrounding the printf? It’s hard to tell what the exact cause of the issue is.

Some possibilities to consider:

  1. You probably want to call this in a loop so the value keeps updating
  2. You might need to flush the stream so the output shows up. This can be done by adding a \n after the %.2f.
  3. Make sure that your brain is connected to your computer through the USB cable. You should be able to do it with a controller, but you will get a better connection with the brain.
2 Likes
#5

Here is some of the code as well as some of the output
Code:
#include “vex.h”

using namespace vex;

event checkRed = event();
event checkBlue = event();
event checkGreen = event();

void hasBlueCallback() {
Brain.Screen.setFont(mono40);
Brain.Screen.clearLine(1, black);
Brain.Screen.setCursor(Brain.Screen.row(), 1);
Brain.Screen.setCursor(1, 1);
Controller1.Screen.clearScreen();
Controller1.Screen.setCursor(1,1);
Vision10.takeSnapshot(Vision10__SIG_1);
if (Vision10.objectCount > 0) {
Brain.Screen.print(“I see you”);
Controller1.Screen.print(“I see you”);
printf(“CenterX:”);
//printf("%.2f", (double)Vision10.objects[0].centerX);
printf("%.2f", (double)Vision10.largestObject.centerX);
printf(“CenterY”);
//printf("%.2f", (double)Vision10.objects[0].centerY);
printf("%.2f", (double)Vision10.largestObject.centerY);
//this_thread::sleep_for(10);
} else {
Brain.Screen.print(“No Blue Object”);
Controller1.Screen.print(“No Blue Object”);
}
}

int main() {
// Initializing Robot Configuration. DO NOT REMOVE!
vexcodeInit();

checkBlue(hasBlueCallback);

while (true) {
checkBlue.broadcastAndWait();
wait(1, seconds);
}
}

Output:
CenterX:145.00CenterY132.00CenterX:145.00CenterY133.00CenterX:145.00CenterY133.00CenterX:145.00CenterY132.00CenterX:143.00CenterY134.00CenterX:143.00CenterY135.00CenterX:222.00CenterY112.00CenterX:253.00CenterY140.00CenterX:47.00CenterY123.00CenterX:105.00CenterY127.00CenterX:105.00CenterY128.00CenterX:105.00CenterY129.00CenterX:105.00CenterY129.00CenterX:106.00CenterY127.00CenterX:264.00CenterY131.00CenterX:176.00CenterY99.00CenterX:38.00Cente
rY118.00CenterX:11.00CenterY158.00CenterX:10.00CenterY83.00CenterX:12.00CenterY99.00CenterX:9.00CenterY100.00CenterX:11.00CenterY100.00CenterX:12.00CenterY97.00CenterX:10.00CenterY106.00CenterX:10.00CenterY106.00CenterX:11.00CenterY159.00CenterX:11.00CenterY90.00CenterX:12.00CenterY99.00CenterX:11.00CenterY95.00CenterX:11.00CenterY90.00CenterX:11.00CenterY89.00CenterX:12.00CenterY95.00CenterX:11.00CenterY100.00CenterX:12.00CenterY100.00CenterX:
11.00CenterY91.00CenterX:11.00CenterY97.00CenterX:12.00CenterY92.00CenterX:11.00CenterY88.00CenterX:11.00CenterY88.00CenterX:11.

I cannot check if there is a difference with using wired mode for a few days but I will see if there is a difference when I can, thanks for the support.
(PS: cant get the code to indent properly, sorry if that makes it harder to read)