• Motivation

• What is OpenGL

• Using OpenGL with Perl

• Future improvements

There are lots of pretty pictures and animations in this talk

They have all been programmatically generated

But not by me

• Max Maischein

• Frankfurt.pm

• Perl since 2000

• HTC Vive + NVidia 1080 since 2016

• CGI

• Computer Generated Images

• BBS / Demoscene

• New hardware must be mastered

• Video postprocessing (App::VideoPlayer)

OpenGL is an abstraction layer and language for access to (accellerated) (graphics) (hardware)

• Just because it's hardware, it's not necessarily accellerated

• The hardware is not only for graphics

• MESA is a software OpenGL implementation

OpenGL 1.0 - Language - released in 1992

• OpenGL is a C API

• glBegin(), glColor(), glDraw...(), glEnd()

• Completely procedural, not descriptive

• Linear functions for data/texture lookup

• Limited by how fast the CPU can issue commands

OpenGL 2.0 - 4.5 - shader programs (2004-2015)

• Let the hardware do more work

• Allow user-supplied programs ("shaders") for data lookup

• Shader programs combine scene setup and colouring

• GLSL is very restricted C

• Runs on the GPU

• No recursion

• No variable length loops

• Compiler included in OpenGL

OpenGL 4.0 - "modern"

Let the hardware do even more work

• GPUs get memory management

• Shaders can write to GPU buffers never intended for display

• Can do computations

• CUDA / GPGPU

 1:  use OpenGL ':all';

• only OpenGL 1.x and 2.0 functions

• Perl is not good at number pushing

• PDL, SDL help

 1:  # go to Github
 2:  use OpenGL::Glew;
 3:  # use OpenGL::Modern; # soon

• All functions up to OpenGL 4.5

• Ideally API compatible with OpenGL.pm

• Perl as glue language

• let GLSL do the heavy lifting

OpenGL is like Perl

• Battle tested

• Available even on Linux, HTML5, ...

• Much bad/outdated documentation

• Read the OpenGL FAQ

• Do calculations as much outside of Perl as possible

• GLSL can be very terse

 1:  void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
 2:  vec2 uv = fragCoord.xy / iResolution.xy;
 3:    fragColor = vec4(uv,0.5+0.5*sin(iGlobalTime),1.0);
 4:  }
 5:  void main() {
 6:    vec4 color = vec4(0.0,0.0,0.0,1.0);
 7:    mainImage( color, gl_FragCoord.xy );
 8:    gl_FragColor = color;
 9:  }

 1:  void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
 2:    vec2 uv = fragCoord.xy / iResolution.xy;
 3:    fragColor = vec4(uv,0.5+0.5*sin(iGlobalTime),1.0);
 4:  }
 5:  void main() {
 6:    vec4 color = vec4(0.0,0.0,0.0,1.0);
 7:    mainImage( color, gl_FragCoord.xy );
 8:    gl_FragColor = color;
 9:  }

main() just like in C

 1:  void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
 2:    vec2 uv = fragCoord.xy / iResolution.xy;
 3:    fragColor = vec4(uv,0.5+0.5*sin(iGlobalTime),1.0);
 4:  }
 5:  void main() {
 6:    vec4 color = vec4(0.0,0.0,0.0,1.0);
 7:    mainImage( color, gl_FragCoord.xy );
 8:    gl_FragColor = color;
 9:  }

vec4 - four-float variable

 1:  void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
 2:    vec2 uv = fragCoord.xy / iResolution.xy;
 3:    fragColor = vec4(uv,0.5+0.5*sin(iGlobalTime),1.0);
 4:  }
 5:  void main() {
 6:    vec4 color = vec4(0.0,0.0,0.0,1.0);
 7:    mainImage( color, gl_FragCoord.xy );
 8:    gl_FragColor = color;
 9:  }

gl_FragCoord - variable for the coordinates of the current pixel (x,y,z,w)

mainImage(...) - function call

 1:  void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
 2:    vec2 uv = fragCoord.xy / iResolution.xy;
 3:    fragColor = vec4(uv,0.5+0.5*sin(iGlobalTime),1.0);
 4:  }
 5:  void main() {
 6:    vec4 color = vec4(0.0,0.0,0.0,1.0);
 7:    mainImage( color, gl_FragCoord.xy );
 8:    gl_FragColor = color;
 9:  }

iResolution - variable sent from Perl

iGlobalTime - variable sent from Perl

 1:  void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
 2:    vec2 uv = fragCoord.xy / iResolution.xy;
 3:    fragColor = vec4(uv,0.5+0.5*sin(iGlobalTime),1.0);
 4:  }
 5:  void main() {
 6:    vec4 color = vec4(0.0,0.0,0.0,1.0);
 7:    mainImage( color, gl_FragCoord.xy );
 8:    gl_FragColor = color;
 9:  }

gl_FragColor - (output) variable for the pixel color (r,g,b,a)

• Fragment shader live editor

• Based on an idea by Inigo Quilez and Pol Jeremias

• https://www.shadertoy.com

• But in Perl

• Prima, Prima::OpenGL, OpenGL::Glew

See here ->

Not yet on CPAN

 1:    git clone https://github.com/Corion/app-shadertoy.git
 2:    cd app-shadertoy
 3:    cpanm --installdeps .
 4:    perl Makefile.PL
 5:    make
 6:    perl -Mblib -w scripts/shadertoy.pl -c shaders/demo.yml

Thank you!

Questions?

Questions?

App::ShaderToy - https://github.com/Corion/app-shadertoy

corion@cpan.org

Slides will be at http://corion.net/talks/

• My second XS module

• Move OpenGL::Glew into OpenGL::Modern (Chris Marshall and Mithaldu)

• https://github.com/chm-devel/opengl-modern

• Real world usages for compute shaders (parallel Regexp execution?)

• Should I use Perl for my first Game / VR experience?

• Ecosystem: Unity / Asset store / shader marketplace

• Can you help me with OpenGL?

• OpenGL Red Book

• Can you help me with matrix multiplication?

• OpenGL+GLSL is like HTML+Javascript

• OpenGL is far too high level

• OpenGL is not suited towards graphics engines

• HTML+Javascript move towards WebAssembly

• No compiler in the OpenGL driver needed

• Nobody likes OpenGL programming

• Everybody writes their own wrapper

• I like GLSL programming

• Trying to keep wrappers/frameworks at bay

• Raw framebuffer access

• Abstractions (X11, GDI, OpenGL, DirectX)

• HTML + Javascript in the browser

• HTML5 <canvas>

• WebGL

Why a programming language?

• C is on the wrong side of the CPU / GPU divide

• C is too powerful, not suited for parallelism (pointer aliasing)