Output/save animations and parameter sweep visualizations

[thsmit]

Dear all,

I am experimenting with nicely outputting animations and visualizations of parameter sweeps like:

• Animation manifolds
• More manifolds
• The parameter sweep in here

I am getting quite a long way with Ex_TimelapseAnimation.cs but how can we output these animations. Do we need to save screenshots and make a git out of that or is there some other rendering involved? I am keen to learn more how this is done :)

Best, Thijs

[LinKayser]

Hi @thsmit — for the PicoGK-based screenshots, I usually render out repeated screenshots as TGA, and then convert them to an animation using Quicktime (Open Frame Sequence) or another tool. Since Quicktime doesn't understand TGA, it's a bit of a pain to convert to PNG or something else first. I didn't want to burden the core PicoGK with further submodules, so I did not implement PNG natively in regular PicoGK.

The more nice renders were done in Blender, and I wish Blender had a nice C-type interface that we could use to automate it. Unfortunately it seems to only support Python code that is executed from within Blender. I am thinking of adding some clever inter-process communication between PicoGK and Blender as setting up stuff takes forever. But for now, that's how I do this.

Let me know if this helps.

PS: To convert the TGAs to PNGs, which can directly be loaded in Quicktime, you can add the following code (Requires the SkiaSharp NuGet package). All you do is load the TGA from the screenshot into an image, and save it again as PNG. Then you can delete the TGA.

It's on my list of things I will change for a more extended version of PicoGK, I am working on.

//
// SPDX-License-Identifier: Apache-2.0
//
// PicoGK ("peacock") is a compact software kernel for computational geometry,
// specifically for use in Computational Engineering Models (CEM).
//
// For more information, please visit https://picogk.org
// 
// PicoGK is developed and maintained by LEAP 71 - © 2023-2024 by LEAP 71
// https://leap71.com
//
// Computational Engineering will profoundly change our physical world in the
// years ahead. Thank you for being part of the journey.
//
// We have developed this library to be used widely, for both commercial and
// non-commercial projects alike. Therefore, we have released it under a 
// permissive open-source license.
//
// The foundation of PicoGK is a thin layer on top of the powerful open-source
// OpenVDB project, which in turn uses many other Free and Open Source Software
// libraries. We are grateful to be able to stand on the shoulders of giants.
//
// LEAP 71 licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with the
// License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
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// PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED.
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// See the License for the specific language governing permissions and
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//

using PicoGK;
using SkiaSharp;

namespace PicoGK
{
    public static class SKHelpers
    {
        public static SKColor oAsSkColor(this ColorFloat clr)
        {
            return new SKColor( (byte)(clr.R * 255.0f),
                                (byte)(clr.G * 255.0f),
                                (byte)(clr.B * 255.0f),
                                (byte)(clr.A * 255.0f));
        }

        public static ColorFloat clrAsColorFloat(this SKColor clr)
        {
             return new ColorFloat( clr.Red     / 255.0f,
                                    clr.Green   / 255.0f,
                                    clr.Blue    / 255.0f,
                                    clr.Alpha   / 255.0f);
        }
    }

    public partial class Image
	{
        public static ImageColor imgFromSKBitmap(SKBitmap oSKBitmap)
        {
            ImageColor img = new ImageColor(oSKBitmap.Width, oSKBitmap.Height);

            for (int x = 0; x < img.nWidth; x++)
            {
                for (int y = 0; y < img.nHeight; y++)
                {
                    SKColor oSKColor = oSKBitmap.GetPixel(x,y);

                    img.SetValue( x, img.nHeight - y - 1, oSKColor.clrAsColorFloat());
                }
            }

            return img;
        }

        public static implicit operator SKBitmap(Image img)
        {
            SKBitmap skBitmap = new SKBitmap(   img.nWidth,
                                                img.nHeight,
                                                SKColorType.Rgba8888,
                                                SKAlphaType.Unpremul);

            for (int x = 0; x < img.nWidth; x++)
            {
                for (int y = 0; y < img.nHeight; y++)
                {
                    skBitmap.SetPixel(x, img.nHeight - y - 1, img.clrValue(x, y).oAsSkColor());
                }
            }

            return skBitmap;
        }

        public void SavePng(string strFileName)
		{
            using (SKImage  skImg   = SKImage.FromBitmap(this))
            using (SKData   skData  = skImg.Encode(SKEncodedImageFormat.Png, 100))
            {
                // Step 4: Write the SKData to a file
                using (FileStream fileStream = File.OpenWrite(strFileName))
                {
                    skData.SaveTo(fileStream);
                }
            }
        }
	}
}

[thsmit]

Hi @LinKayser,

Thanks for the explanation and the code, this helps a lot! Converting from .tga to .png works nicely using the code you suggested. The Blender part I will save for a later point in time ;) Herewith the function to loop though a folder and convert all .tga files to .png. Maybe it helps anyone.

public static void ConvertAll(string strFolder)
{

    // Get a list of all .tga files in the folder
    List<string> tgaFiles = new List<string>(Directory.GetFiles(strFolder, "*.tga"));

    // Loop through the list
    foreach (string file in tgaFiles)
    {

        // load in image
        Console.WriteLine("File: " + file);
        TgaIo.LoadTga(file, out Image img);

        // save as png
        img.SavePng(Path.ChangeExtension(file, ".png"));

        // delete tga
        File.Delete(file);
    }
}