how to translate camera on Y axis by angle

[SkyEric]

Hi. The Camera class has a method Camera#translate(dX,dY)

If you want to rotate the camera around y axis, just call Camera#translate() method with dY=0 and dX=x. That means there is no movement vector up or down but "x" to the right or left.

/**
* Translation is the movement that makes the Earth around the Sun.
* So in this context, translating the camera means moving the camera around the Zero (0,0,0)
*

* This implementation makes uses of 3D Vectors Algebra.
*

* The idea behind this implementation is to translate the 2D user vectors (the line in the
* screen) with the 3D equivalents.
*

* In order to to that, we need to calculate the Right and Arriba vectors so we have a match
* for user 2D vector.
*
* @param dX the X component of the user 2D vector, that is, a value between [-1,1]
* @param dY the Y component of the user 2D vector, that is, a value between [-1,1]
*/
public synchronized void translateCamera(float dX, float dY) {
if (getDelegate() != null){
getDelegate().translateCamera(dX, dY);
}
}

How does it relate to 0 to 180 degrees on the Y-axis? Let's say I want to rotate 30 degrees about the Y-axis, what do I do? The interval [-1, 1] does not evenly divide 360 degrees by percentage?

Originally posted by @SkyEric in #83 (comment)

[andresoviedo]

Hello @SkyEric

I guess you can try the following method to get your euler translation by angle.

Regards

    float degrees = 30; 
    float xRot = 0f,  yRot = degrees, zRot = 0f;

    float radians = Math.toRadians(degrees);
    float[] buffer = new float[16];
    Math3DUtils.createRotationMatrixAroundVector(buffer,` 0, radians, xRot, yRot, zRot);

    float[] newBuffer = new float[12];
    Math3DUtils.multiplyMMV(newBuffer, 0, buffer, 0, coordinates, 0);


    pos[0] = newBuffer[0];
    pos[1] = newBuffer[1];
    pos[2] = newBuffer[2];
    up[0] = newBuffer[8];
    up[1] = newBuffer[8 + 1];
    up[2] = newBuffer[8 + 2];

[SkyEric]

Hello @SkyEric

I guess you can try the following method to get your euler translation by angle.

Regards

    float degrees = 30; 
    float xRot = 0f,  yRot = degrees, zRot = 0f;

    float radians = Math.toRadians(degrees);
    float[] buffer = new float[16];
    Math3DUtils.createRotationMatrixAroundVector(buffer,` 0, radians, xRot, yRot, zRot);

    float[] newBuffer = new float[12];
    Math3DUtils.multiplyMMV(newBuffer, 0, buffer, 0, coordinates, 0);


    pos[0] = newBuffer[0];
    pos[1] = newBuffer[1];
    pos[2] = newBuffer[2];
    up[0] = newBuffer[8];
    up[1] = newBuffer[8 + 1];
    up[2] = newBuffer[8 + 2];

Tried it but it didn't work. How is coordinates defined?
Here is my definition:
final float[] coordinates = new float[12];
coordinates[0] = pos[0];
coordinates[1] = pos[1];
coordinates[2] = pos[2];
coordinates[3] = 1;
coordinates[4] = getxView();
coordinates[5] = getyView();
coordinates[6] = view[2];
coordinates[7] = 1;
coordinates[8] = getxUp();
coordinates[9] = getyUp();
coordinates[10] = getzUp();
coordinates[11] = 1;

in addition. Is there any problem with the initial value of xRot、yRot、zRot?
@andresoviedo

[andresoviedo]

.hello @SkyEric

That is correct

Coordinates is a buffer containing all 3 camera coordinates.

Those coordinates must be transformed using the transformation matrix given by createRotationMatrix.

Yes. There may be an issue in the pseudo code..please try declaring each variable independently.

Regards

[andresoviedo]

Hello @SkyEric

Thank you for your feedback
i think I now understand your need

I am guessing we are talking about AR
And in this case indeed angle & orientation are keys

I did a poc a while ago and I think I implemented that already
you might want to see this code
i think it's all you need

private void setupOrientationListener()
https://github.com/the3deers/android-3D-model-viewer/blob/master/app/src/main/java/org/andresoviedo/app/model3D/view/ModelActivity.java#L204

public void onOrientationChanged(int orientation)
https://github.com/the3deers/android-3D-model-viewer/blob/master/engine/src/main/java/org/andresoviedo/android_3d_model_engine/services/SceneLoader.java#L969

public void setOrientation(int angle)
https://github.com/the3deers/android-3D-model-viewer/blob/master/engine/src/main/java/org/andresoviedo/android_3d_model_engine/model/Camera.java#L289

Regards

[SkyEric]

Thank you for your reply.

I have seen this part of the logic before. But it is rotating around the Z axis. This doesn't do what I want, I want to rotate around the Y axis.
@andresoviedo