I finally took the time to clean up this project and make a public release. In the packages you will find binaries and source code for the application, so if you’re thinking of using it and come up with something nice, let me know. After the first release i have fixed some problems with memory access and crashes. I have also added a simple UI for easy pick of tags from the “data/tags” folder on your hard-drive.

What is it?
- GML Viscosity is an experiment. It is application used to draw GML tags on a viscous liquid rendered purely on the GPU side.

What does it do?
- It liquifies your tags, in a way you can hardly read them but still looks cool (thats graffiti).
- It is possible to load gml files from the disk or directly from the “lots of zeros”book database.

How can I interact?
- Not implemented on this version. This version selects and draw gml files randomly from the web or from a tags folder. For a smart person it should be easy to add mouse support. The code is also prepared to support multitouch so, it should be easy to implement TUIO and create your multitouch version.
- Use ‘r’ key to randomly fetch a new tag from the website and if available it will draw it on the screen.
- Use the GUI window to pick any tag from the folder “tags” inside data folder.

Where can i get it?
Windows Version | MacOSX Version

Have fun.

There are some problems with reading/writing from/to GL textures. For some reason it crashes on me. I have been working with JavaCL‘s author, so hopefully it will be working soon.

:: Download

Download it, install it and try it.
If you find any problems or if you have suggestions, let me know.

Have fun.

So imagine we have 2 image buffers Image1, Image2. Usually to change data from Image1, you would simply access it and write directly back to the same positioion. Now, when we’re talking about a shader fragment program we can’t simply do that. You may ask now, what’s the solution? Ping-pong it!

Here is what i’m talking about:

//
// Initialization
//
int W = 100;
int H = 100;
ImageArray = new int[2][W*H];
int CurrActiveBuffer = 0; // Current active buffer index
 
 
//
// Mainloop
//
for( int j=0; j<H; j++ )
{
	for( int i=0; i<W; i++ )
	{
		// ERROR! Write to same buffer. Not possible in gpu shader
		//Image1[i+j*W] = Image1[i+j*W] * 2;  // Mul by 2
 
		// Ping-pong version
		int src = CurrActiveBuffer; // Current active buffer (Input)
		int dest = 1-CurrActiveBuffer;  // Back buffer (Output)
		Image1[dest][i+j*W] = Image1[src][i+j*W] * 2;  // Mul by 2
	}
}
 
// Swap back and front buffers (read becomes write and vice-versa)
CurrActiveBuffer = 1-CurrActiveBuffer;    // CurrActiveBuffer ? 0 : 1;

As you can see we start with buffer 0. That’s where we get out data from (read) and write it to Buffer 1. Once the operation is done, we swap buffers and so on. This way we’ll be able to use last iteration’s data as input for the next iteration.

Now let’s put this in OpenGL way. I will be using a FrameBufferObject (FBO) and 2 textures here. The framebuffer will be holding to both textures as 2 Color Attachments. So let’s get coding:

//
// Initialization
//
int W = 100;
int H = 100;
int FboID;
int TexID[2];
int CurrActiveBuffer = 0;  // Current active buffer index
 
// Create the frambuffer
glGenFramebuffersEXT( 1, &FboID );
glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, FboID );
 
// Create 2 textures for input/output.
glGenTextures( 2, TexID );
 
for( int i=0; i<2; i++ )
{
	glBindTexture( GL_TEXTURE_2D, TexID[i] );
	glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
	glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
	glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
	glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
	glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, W, H, 0, GL_RGBA, GL_FLOAT, NULL );
	if( _hasMipmapping )  glGenerateMipmapEXT( GL_TEXTURE_2D );
}
 
// Now attach textures to FBO
int src = CurrActiveBuffer;
int dest = 1-CurrActiveBuffer;
glFramebufferTexture2DEXT( GL_FRAMEBUFFER_EXT, 
                           GL_COLOR_ATTACHMENT0_EXT, 
                           GL_TEXTURE_2D, TexID[src], 0 );
glFramebufferTexture2DEXT( GL_FRAMEBUFFER_EXT, 
                           GL_COLOR_ATTACHMENT1_EXT, 
                           GL_TEXTURE_2D, TexID[dest], 0 );
);
 
 
 
//
// Mainloop
//
int src = CurrActiveBuffer;
int dest = 1-CurrActiveBuffer;
 
FBO.Bind();
 
glDrawBuffer( dest );
 
glBindTexture( GL_TEXTURE_2D, TexID[src] );
ShaderProgram.SetTextureUniform( 0 );
RenderScene();
 
FBO.Unbind();
 
 
// Swap back and front buffers (read becomes write and vice-versa)
CurrActiveBuffer = 1-CurrActiveBuffer;    // CurrActiveBuffer ? 0 : 1;

Why would you want to ping-pong? Well for instance imagine you are doing a water effect in the gpu? You need to access data from your previous buffer right? In the CPU that would be trivial as you know but if you want to push it’s limits by using GPU this is the next step for you.

Have fun.

On this case we will need 4 points: 2 anchor points (the line end points) and 2 control points. The control points won’t really touch the curve, they work more as directional information on the curve itself.

As we need to send this data to the shader i have decided to use  LINES as input primitive, 2 points define a line so it’s perfect, we’ll use that for the 2 anchor points. As for the control points 2 different texture units (glMultiTexCoord3f) attached to the line’s vertex data will do. Using geometry shaders besides setting the input primitive type we also need to set the output type. LINE_STRIP is fine, as it works perfectly for what we’re doing. That’s all on the application side.

On the vertex shader side it’s pretty simple:

[VERTEX SHADER]
void main( void )
{
    gl_FrontColor = gl_Color;
    ControlPoint1 = gl_MultiTexCoord0.xyz;
    ControlPoint2 = gl_MultiTexCoord1.xyz;
 
    gl_Position = gl_Vertex;
}

What the code is doing is sending the data further down the pipeline to the geometry shader, where all the magic happens. At this stage, having both Anchor and Control points we can now define the curve by a given detail. Think of detail as a number of step-points along the curve which makes it look smoother or flatten (tesselation, subdivision, smoothing, etc).

Both control points are sent by the application for the geometry shader, still, as in the the vertex shader comes before the geometry shader, we will need to send them down on the vertex-shader, otherwise the GS won’t be able to “see” them (i know, hurray for Cg). We’re now almost done. By using the function from the above link(s) and as shown below we compute the curve with a given detail on the geometry shader, by generating new vertices along the curve purely on the gpu side. I think it to be pretty straightforward and the code should be self-explanatory.

[GEOMETRY SHADER]
uniform int g_Detail;
varying in vec3 ControlPoint1[];
varying in vec3 ControlPoint2[];
 
// Found in nvidia sdk
vec3 evaluateBezierPosition( vec3 v[4], float t )
{
    vec3 p;
    float OneMinusT = 1.0 - t;
    float b0 = OneMinusT*OneMinusT*OneMinusT;
    float b1 = 3.0*t*OneMinusT*OneMinusT;
    float b2 = 3.0*t*t*OneMinusT;
    float b3 = t*t*t;
    return b0*v[0] + b1*v[1] + b2*v[2] + b3*v[3];
}
 
void main()
{
    vec3 pos[4];
    pos[0] = gl_PositionIn[0].xyz;
    pos[1] = ControlPoint1[0];
    pos[2] = ControlPoint2[0];
    pos[3] = gl_PositionIn[1].xyz;
    float OneOverDetail = 1.0 / float(g_Detail-1.0);
    for( int i=0; i<g_Detail; i++ )
    {
        float t = i * OneOverDetail;
        vec3 p = evaluateBezierPosition( pos, t );
        gl_FrontColor = gl_FrontColorIn[0]; 
        gl_Position = gl_ModelViewProjectionMatrix * vec4( p.xyz, 1.0 );
        EmitVertex();
    }
 
    EndPrimitive();
}

What’s next? That is up to you. You’re not going to leave me with all the work, are you ?

Download the example + source.
You will also need to install Vitamin 0.5.6 as the project is built with it.

Download: http://victamin.googlecode.com/files/JavaCL_1_4b.zip

Have fun!

I have only tested this under Windows XP 64bit with ATI Stream SDK and Nvidia drivers. If you find any problem, please report.
One other thing: Memo’s example isn’t the real thing. It’s simply the CL program. So you won’t be able to get all the fuzzy million particles around. Not yet.

Library/Examples available here: http://victamin.googlecode.com/files/OpenCL4Java_1b.zip

Installation steps:
1. Copy the library to processing’s libraries folder
2. Install ATI Stream SDK (i have packed the OpenCL.dll file, still you might have to install the whole pack). If you’re using Nvidia, install the OpenCL drivers and toolkit
3. Open the example and run it.

Enjoy and have fun!

During my research i came across this Pirelenito’s website with a great example on using FOBS+JMF, exactly what i needed. So i  downloaded it and started working on it, putting into it a bit of myself.

So here it is, a first pre-beta version of a library capable of rendering movie files (with sound) with Java/Processing without much effort.

NOTE! I’m still having problems with a couple of codecs like DivX, Xvid, H264. It crashes on me when rendering some of these, but it works just fine for Mpeg4, PhotoJPEG, Cinepak. It isn’t perfect, but if you be careful and use the right format/codec it will go smooth. Meanwhile i will be working on a better version.

Website: www.pixelnerve.com/processing/libraries/moviegl
Library Package(s) at: :  http://code.google.com/p/victamin/downloads/list

Have fun!

Credits goto Pirelenito. Thanks for sharing.

The technique used is called ‘off-axis frustum’ a.k.a the “right way”, courtesy of Paul Bourke. If you want to read more about it you should pay a visit to his website.

2 images are rendered from 2 different point of views, creating two images with some little differences between them. The off-axis frustum means the point of view might not lie on the perpendicular line to the ‘view-area’.  These 2 images are then sent to a simple shader that takes the R channel from the left-eye buffer, the GB channels from the right-eye buffer and then mixes it into a single stereo image. This is the color glasses compositing method, but it sure is possible to just send both images down the two adapters of your videocard and get the same 3d feeling (with colors) using an Head-Mounted Display or a multi-projector system of some kind.

Source code available here.

You will need ‘Vitamin’ library. Just copy it to processing’s libraries folder as usual, and then run the project.

Watch Sunflower

Download source code

Hope you enjoy it

ObjImp + Mri3ds libraries are now officially part of the Processing’s libraries page.
That means more updates and bug fixes.

____________________________________________________________________
Mri3ds v1.2 has been released
* Wrapper data structures moved into the library.
* V3dsScene is now part of the library. Look at the examples on how to load a .3ds scene.

____________________________________________________________________

ObjImp v1.1 has been released.
* Wrapper data structures moved into the library.
* ObjImpScene is now part of the library. Look at the examples on how to load a .obj scene.

.