Smooth camera movement

Hello everyone.
I am trying to make player look at entity. Everything works fine, but I want to make camera move smoother. Now it just "stands" at one point and whenever I try to move camera, it's coming back to a point in very ugly way. Here's my code:

public static void lookAt(EntityPlayer player) {
        EntityLiving ent = getFocusEntity();
        double endX = ent.posX;
        double endY = ent.posY - ent.getEyeHeight() + (ent.height - 1);
        double endZ = ent.posZ;
        double deltaX = endX - player.posX;
        double deltaY = endY - player.posY;
        double deltaZ = endZ - player.posZ;
        double hypotenuse = Math.sqrt(deltaX * deltaX + deltaZ * deltaZ);
        float rotationYaw = (float) Math.toDegrees(Math.atan2(deltaX, deltaZ));
        float rotationPitch = (float) Math.toDegrees(Math.atan2(deltaY, hypotenuse));
        

        player.rotationYaw = -rotationYaw;
        player.prevRotationYaw = -rotationYaw;
        player.rotationPitch = -rotationPitch;
        player.prevRotationPitch = -rotationPitch;    
        //player.capabilities.setPlayerWalkSpeed(0.05F);
    }

I've found a smooth camera's code (one that turns on with F8), but don't know what to do with it.

if (this.mc.gameSettings.smoothCamera)
        {
            float f = this.mc.gameSettings.mouseSensitivity * 0.6F + 0.2F;
            float f1 = f * f * f * 8.0F;
            this.smoothCamFilterX = this.mouseFilterXAxis.smooth(this.smoothCamYaw, 0.05F * f1);
            this.smoothCamFilterY = this.mouseFilterYAxis.smooth(this.smoothCamPitch, 0.05F * f1);
            this.smoothCamPartialTicks = 0.0F;
            this.smoothCamYaw = 0.0F;
            this.smoothCamPitch = 0.0F;
        }
        else
        {
            this.smoothCamFilterX = 0.0F;
            this.smoothCamFilterY = 0.0F;
            this.mouseFilterXAxis.reset();
            this.mouseFilterYAxis.reset();
        }

if (this.mc.gameSettings.smoothCamera)
            {
                this.smoothCamYaw += f2;
                this.smoothCamPitch += f3;
                float f4 = partialTicks - this.smoothCamPartialTicks;
                this.smoothCamPartialTicks = partialTicks;
                f2 = this.smoothCamFilterX * f4;
                f3 = this.smoothCamFilterY * f4;
                this.mc.thePlayer.setAngles(f2, f3 * (float)i);
            }
            else
            {
                this.smoothCamYaw = 0.0F;
                this.smoothCamPitch = 0.0F;
                this.mc.thePlayer.setAngles(f2, f3 * (float)i);
            }