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| author | Sven Gothel <[email protected]> | 2011-07-13 03:08:39 +0200 |
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| committer | Sven Gothel <[email protected]> | 2011-07-13 03:08:39 +0200 |
| commit | 5dc5f36caf831b15c94b4d059577b1c461ea6cd3 (patch) | |
| tree | badf88cfb3f0bbcc79a7f827ce4f9f5ae300186e | |
| parent | bdeed41cd4d48e13e1a00bf7030975ddcc79cff6 (diff) | |
Add Documentation: OpenGL-Evolution-And-JOGL
| -rw-r--r-- | doc/Overview-OpenGL-Evolution-And-JOGL.html | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/doc/Overview-OpenGL-Evolution-And-JOGL.html b/doc/Overview-OpenGL-Evolution-And-JOGL.html new file mode 100644 index 000000000..a2676c7c5 --- /dev/null +++ b/doc/Overview-OpenGL-Evolution-And-JOGL.html @@ -0,0 +1,214 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> + <link href="../../style.css" rel="stylesheet" type="text/css"/> + <title>OpenGL Evolution & JOGL</title> + </head> + <body> + <div id="container"> + <div id="header"> + <div id="slogan">OpenGL & JOGL</div> + <div id="logo"><a href="http://jogamp.org/">OpenGL & JOGL</a></div> + </div> + <div id="menu"> + <ul> + <li><a href="http://jogamp.org/">Home</a></li> + <li><a href="../../gluegen/www/">Gluegen</a></li> + <li><a href="../../joal/www/">JOAL</a></li> + <li><a href="../../jocl/www/">JOCL</a></li> + <li><a href="../../jogl/www/">JOGL</a></li> + <li><a href="../../demos/www/">Demos</a></li> + <li><a href="../../wiki/">Wiki</a></li> + <li><a href="../../deployment/jogl-next/javadoc_public/">JavaDoc</a></li> + <li><a href="../../blog/">Blogs</a></li> + <li><a href="../../forum.html">Forums</a></li> + </ul> + </div> + <div id="main"> + <div id="text" class="fill"> + <h2>OpenGL Evolution & JOGL</h2> + + <h3>OpenGL Evolution</h3> + <hr/> + +<P> +OpenGL is an application programming interface (API) giving application developers +access to hardware accelerated 3D rendering (incl. 2D).</P> + +<P> +SGI released the first OpenGL specification in January 1992. +Since this point OpenGL 1.x constantly evolved, first under the ARB and later under the Khronos Group.</P> + +<P> +The OpenGL API was specified with the objective of maximal hardware acceleration, +ie the API functions shall be implemented in hardware - as much as possible. +Further more, OpenGL is considered a vendor neutral and platform agnostic API, +ie should run anywhere, implemented by all 3D GPU manufacturer.</P> + +<P> +Up until OpenGL 1.5, released in July 2003, the core API reflected the so called fixed function pipeline (FFP). +FFP allowed a user to pass triangles, textures and attributes to the GPU. +The attributes had to be utilized to select predefined function of rendering, +hence the name fixed function.</P> + +<P> +Around 2000 new types of GPU hardware evolved, +allowing custom code running on the GPU hardware, +instead of being restricted to the fixed function rendering code.</P> + +<P> +To allow processing of such user defined algorithms on the GPU, +in 2002 the programmable shader pipeline (PSP) was introduced. +The OpenGL Shading Language (GLSL) used to write such shader programs +became an extension to OpenGL 1.4.</P> + +<P> +GLSL allows users to +<ul> + <li> write ANSI-C like shader programs</li> + <li> compile shader programs</li> + <li> upload shader programs to the GPU </li> +</ul></P> + +<P> +The shader, executed on the GPU, transform the +triangle position and determine the pixel color.</P> + +<P> +Within this process, the shader may use any form of data, +arrays, textures and framebuffer. +It reads it, computes and stores the result in the target framebuffer(s), +hence the name programmable.</P> + +<P> +In September 2004, GLSL subsumed into the core OpenGL 2.0 API, +hence OpenGL 2.0 supported both, FFP and PSP.</P> + +<P> +The desire to utilize OpenGL on embedded devices increased +the more 3D capabilities appeared.</P> + +<P> +Around 2005 a subset of the FFP of OpenGL 1.3 +for embedded systems was released, OpenGL ES 1.0.</P> + +<P> +In March 2007 a programmable shader (PSP) only subset of OpenGL 2.0 +for embedded systems was released.</P> + +<P> +In July 2010 OpenGL 4.1 was released and it's core profile +is fully compatible to OpenGL ES 2.0.</P> + +<P> +Today, desktop and embedded GPU's implement the programmatic shader (PSP) +based rendering.</P> + +<P> +Still the fixed function subset is provided by most drivers. +However, since the hardware itself does not implement such functionality anymore, +it is completely implemented in software by the OpenGL driver.</P> + +<P> +This leads to the conclusion it is best advised for OpenGL applications +to avoid the FFP, but using the PSP. This allows the implementor +to utilize application level optimization which usually cannot be reached +by the very generic implemented FFP in the OpenGL drivers.</P> + + <h3>JOGL & The OpenGL Evolution</h3> + <hr/> +<P> +Like <a href="http://jausoft.com/gl4java/">GL4Java</a>, the 1st JOGL release 1.x +mapped OpenGL in one interface. This architecture was feasible and correct until the new OpenGL +profiles surfaced. There was only one unique way to create an OpenGL context for all available +OpenGL versions.</P> + +<P> +The continously developed <a href="http://jogamp.org/">JOGL 2.x</a> reflects the aforementioned OpenGL evolution +by <a href="/deployment/jogamp-next/javadoc/jogl/javadoc/overview-summary.html#overview_description">mapping the OpenGL profiles to interfaces</a>. +This is essential since creating an OpenGL context for each class of OpenGL profiles +requires it's <a href="/deployment/jogamp-next/javadoc/jogl/javadoc/overview-summary.html#GLAPIInclusionCriteria">specific initialisation</a>.<br> +Some OpenGL profiles like + <a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GLES2.html">GLES2</a> +for embedded may not be available on desktop machines.</P> + +<P> +Fixed Function (FFP) Only Profiles: +<ul> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GLES1.html">GLES1</a></li> +</ul></P> + +<P> +Programmable Shader (PSP) Only Profiles: +<ul> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GLES2.html">GLES2</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL3.html">GL3</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL4.html">GL4</a></li> +</ul></P> + +<P> +FFP & PSP Profiles: +<ul> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL2.html">GL2</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL3bc.html">GL3bc</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL4bc.html">GL4bc</a></li> +</ul></P> + +<P> +The following UML diagram show that JOGL also adds common subsets of OpenGL profiles +to allow easy development of multiple target profiles.</P> + +<P> +Common OpenGL Profile Subsets: +<ul> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL.html">GL</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL2ES1.html">GL2ES1</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL2ES2.html">GL2ES2</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL2GL3.html">GL2GL3</a></li> +</ul></P> + +<br> +For example using the common interface +<a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL2ES2.html">GL2ES2</a> +of <a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GL2.html">GL2</a> +and <a href="/deployment/jogamp-next/javadoc/jogl/javadoc/javax/media/opengl/GLES2.html">GLES2</a>, +ensures the code complies with the GL2 and GLES2 profile and an implementation may use both:</P> +<pre> + void renderSomethingForGL2(GL2 gl, int program) { + renderSomethingForGL2AndGLES2(gl, program); + } + + void renderSomethingForGLES2(GLES2 gl, int program) { + renderSomethingForGL2AndGLES2(gl, program); + } + + void renderSomethingForGL2AndGLES2(GL2ES2 gl, int program) { + gl.glValidateProgram(program); + ... + + } +</pre> + +<embed src="bouml/html-svg/fig128069.svg" width="1024" height="600"/> + + <h3>References</h3> +<ul> + <li><a href="http://en.wikipedia.org/wiki/OpenGL">OpenGL on Wikipedia</a></li> + <li><a href="http://en.wikipedia.org/wiki/OpenGL_ES">OpenGL ES on Wikipedia</a></li> + <li><a href="http://en.wikipedia.org/wiki/GLSL">GLSL on Wikipedia</a></li> + <li><a href="/deployment/jogamp-next/javadoc/jogl/javadoc/overview-summary.html#overview_description">JOGL API Overview</a></li> +</ul> + </div> + </div> + <div id="footer"> + <div id="footer_left"> + <span>JogAmp.org</span> + by <a href="http://jogamp.org">http://jogamp.org</a> + is licensed under a <br/> + <a href="http://creativecommons.org/licenses/by/3.0/us/">Creative Commons Attribution 3.0 License</a>. + </div> + </div> + </div> + </body> +</html> |