Anim8or Community

I would like to make floating objects bob with the waves. But I think I must be being thick as I cannot follow what is written under the heading “Controller Expression Script” in https://www.anim8or.com/scripts/spec/index.html

I have tried adding the following to the “Animated toy yacht on sea - 192x128zoom.an8” file I’ve been using, but I just get the error report “Error in reading file” in a pop-up window named “just so you’d know”:
  point3 $bluePos;
  $bluePos = GetAttributePoint3("toy yacht", "position");
  $position = $bluePos + (0, 50, 0);

I have also tried simply declaring an int variable at any point I think it may be acceptable within the .an8 file. But I always get the “Error in reading file” error report.

Can someone point me to a .an8 script that demonstrates how to use the GetAttribute* functions?

Should the above code be inside the scene { "scene01" …} section, or after the closing ‘}’? Or somewhere else?

Thanks,
John

How about this version Ian?

The water is wider than it is deep 192x128 to fill horizon, with small waves so the reflections don't go off the cloud .jpg backdrop. It would have been better if the wave origin wasn’t so far left or at least if it was further back from the grid.

Thanks Johnar!

I added a function to place boat outlines in the water in a script I uploaded on:
https://www.anim8or.com/smf/index.php/topic,6051.0.html
I also posted a couple of YouTube links of the script in action.

/* Function: $addBoat( float $x, float $y, float $direction, float $length, float $width )
 *
 * x,y - Center of boat
 * direction - direction boat is pointing (in radians {radians=PI*degrees/180})
 * length - length of the boat
 * width - width of the boat
 */
int $addBoat( float $x, float $y, float $direction, float $length, float $width )
{
    $dx = sin($direction);
    $dy = cos($direction);
   
    for $angle = 0 to 2*PI step PI / (8 * ($length + $width)) do{
        $len_x = sin($angle) * $length;
        $len_y = cos($angle) * $width;

        $DecayingWaveOrigins.push( ($x + $len_x * $dy - $len_y * $dx,
                                    $y + $len_x * $dx + $len_y * $dy,
                                    1, 12) ); // amplitude, wave length
    }
    return 0;
}

The variable names are a bit odd because I was reusing variables I had already defined.

I should probably add amplitude and wave_length as function parameters!

I’ve had a bit of a play with the animated waves, and tried to give the impression of interaction between an object and water.

I added a function to the script to make a boat hull shaped splash. I felt that otherwise it looks artificial - I probably should do another animation without calling the addBoat() function, and compare them:
/* Function: $addBoat( float $x, float $y, float $direction, float $length, float $width )
 *
 * x,y - Center of boat
 * direction - direction boat is pointing
 * length - length of the boat
 * width - width of the boat
 */

If you set the width to the same value as the length, then your boat is a coracle, or Rover from The Prisoner, as I have animated! (Well a sphere is a lot easier to model than a boat!)

Having the ball bobbing around a bit would help with the realism.

The function adds a number of decaying wave sources around the periphery of the boat:
$DecayingWaveOrigins.push( ($x + $len_x * $dy - $len_y * $dx,
                            $y + $len_x * $dx + $len_y * $dy,
                            1, 12) ); // amplitude, wave length

The last two parameters set the wave height and the wave length.

Anyway here is the result:
[/youtube]

I notice that the video on YouTube isn’t as sharp as the video I uploaded. I have been using the “Intel IYUV codec” for video compression. Is there a better choice for uploading to YouTube?

Sorry I didn't get round to creating wave meshes for each frame.  But Steve had sent me a message indicating he hoped to soon start on implementing a proper solution for animated objects.

I see that he has now done this, or at least implemented a “preliminary version”:
https://www.anim8or.com/smf/index.php/topic,6051.0.html

This is much better than a hacked workaround from me.

I didn't pass the message on, because I didn’t want to raise expectations that Steve was going to deliver functionality, when it could have turned out that there was an unexpected complication meaning he had to ditch the feature.

Regards,
John