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| author | Kevin Rushforth <[email protected]> | 2004-09-17 23:20:57 +0000 |
|---|---|---|
| committer | Kevin Rushforth <[email protected]> | 2004-09-17 23:20:57 +0000 |
| commit | ff2a9c21c9bd840b0ba09f71bff52c063b357f4d (patch) | |
| tree | 844a1da8f8eca2ee63e88849a8c02a8b108ae0f5 /www/j3d1_4/shaders.html | |
| parent | 5c56b1c4c30faa1d3e07d9593acda130a9e723d3 (diff) | |
Updated web pages with rough first draft of ideas for supporting
programmable shaders in Java 3D 1.4.
git-svn-id: https://svn.java.net/svn/j3d-core~svn/trunk@42 ba19aa83-45c5-6ac9-afd3-db810772062c
Diffstat (limited to 'www/j3d1_4/shaders.html')
| -rw-r--r-- | www/j3d1_4/shaders.html | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/www/j3d1_4/shaders.html b/www/j3d1_4/shaders.html new file mode 100644 index 0000000..63c42a6 --- /dev/null +++ b/www/j3d1_4/shaders.html @@ -0,0 +1,209 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> + <meta content="text/html; charset=ISO-8859-1" + http-equiv="content-type"> + <title>Java 3D 1.4 Shaders</title> +</head> +<body> +<h2>Shaders in Java 3D<sup><font size="-2">TM</font></sup> 1.4</h2> +<h4>Introduction and pointer to discussion forum</h4> + +<p>If you wandered over here looking for a completed draft +programmable shading specification for +Java 3D<sup><font size="-2">TM</font></sup> 1.4 that you can +review, you are in the wrong place; or more accurately, the right +place at the wrong time. Come back in about 2 months and things should +be in state where you can review a fairly complete draft +specification. If, on the other hand, you'd like to help us define and +evolve the programmable shading API in Java 3D 1.4, please read +on. +</p> + +<p>This is a very rough first draft of what we are thinking in terms +of programmable shader support in Java 3D 1.4. As we mentioned at +JavaOne, we plan to do the 1.4 API specification under the auspices of +the Java Community Process (JCP). However, we very much want to +involve the larger community in API discussions for programmable +shaders, so please join in the discussion. +</p> + +<p>We have created a thread on the Java 3D discussion forum for +discussing <a +href="http://www.javadesktop.org/forums/forum.jspa?forumID=55" +target="_blank">Java 3D Programmable Shaders</a>. Feel free to +post your comments on our ideas, or post some ideas of your own. +</p> + +<h4>Class Hierarchy for Shader Objects</h4> +<p>The proposed class hierarchy for programmable shaders +in Java 3D is:</p> +<ul> +<li>Abstract shader base classes:</li> +<ul> +<pre>public abstract class ShaderProgram extends NodeComponent +public abstract class Shader extends NodeComponent +</pre> +</ul> +<li>Concrete GL2 shader classes:</li> +<ul> +<pre>public class GL2ShaderProgram extends ShaderProgram + method: {add/remove/get}Shader(GL2Shader) // set of shader objs + method: {add/remove}ErrorListener(GL2ErrorListener) + method: validate(Canvas3D) ??? + +public abstract class GL2Shader extends Shader + public class GL2VertexShader extends GL2Shader + method: set/getShaderSource(String) + method: validate(Canvas3D) ??? + public class GL2FragmentShader extends GL2Shader + method: set/getShaderSource(String) + method: validate(Canvas3D) ??? +</pre> +</ul> +<li>Concrete Cg shader classes:</li> +<ul> +<pre>public class CgShaderProgram extends ShaderProgram + method: {set/get}VertexShader(CgVertexShader) + method: {set/get}FragmentShader(CgFramentShader) + method: {add/remove}ErrorListener(CgErrorListener) + method: validate(Canvas3D) ??? + +public abstract class CgShader extends Shader + public class CgVertexShader extends CgShader + method: set/getShaderSource(String) + method: validate(Canvas3D) ??? + public class CgFragmentShader extends CgShader + method: set/getShaderSource(String) + method: validate(Canvas3D) ??? +</pre> +</ul> +<li>Changes to existing Appearance class (or maybe create new +ShaderAppearance subclass):</li> +<ul> +<pre>public class Appearance extends NodeComponent + ... + method: set/getShaderProgram(ShaderProgram) +</pre> +</ul> +</ul> + +<p>Click on the following link for a preliminary look at the <a +href="javax/media/j3d/ShaderProgram.html">javadoc-generated API +definitions</a> for the newly proposed classes. Note that this is only +the javadoc for the <i>new</i> classes. We know that there are lots of +broken links for the existing classes. +</p> + +<h4>Example Usage</h4> +<p>This is an example code excerpt showing how one might use the new +programmable shader API in a Java 3D program. +</p> +<ul> +<pre>String vertexShaderFile = "my-vertex-shader-file-name"; +String fragmentShaderFile = "my-fragment-shader-file-name"; +String vertexShaderSource; +String fragmentShaderSource; + +// Read CG vertex and fragment shader source code from text files +vertexShaderSource = TextFileUtils.readFully(vertexShaderFile); +fragmentShaderSource = TextFileUtils.readFully(fragmentShaderSource); + +// Create CG vertex and fragment shader objects using the given source code +CgVertexShader vertexShader = new CgVertexShader(vertexShaderSource); +CgFragmentShader fragmentShader = new CgFragmentShader(fragmentShaderSource); + +// Create the CG shader program object and attach the vertex and +// fragment shader objects; add an error listener +CgShaderProgram shaderProgram = new CgShaderProgram(); +shaderProgram.setVertexShader(vertexShader); +shaderProgram.setFragmentShader(fragmentShader); +shaderProgram.addErrorListener(myCgErrorListener); + +// Use CG shader program object in appearance +appearance.setShaderProgram(shaderProgram); +</pre> +</ul> +<h4>Shader Parameters</h4> + +<p>Programmable shaders define two types of parameters: uniform and +varying. As the names imply, uniform parameters are constant (within a +primitive), while varying parameters can vary on per-vertex or +per-fragment basis. +</p> + +<ol> + +<li><b>Uniform parameters</b> (attributes) are those parameters whose +value is constant during the rendering of a primitive. Their values +may change from primitive to primitive, but are constant for each +vertex (for vertex shaders) or fragment (for fragment shaders) of a +single primitive. Examples of uniform parameters include a +transformation matrix, a texture map, lights, lookup tables, +etc. Several Java 3D state attributes are automatically available +to the shader program as pre-defined uniform parameters. The +application doesn't need to do anything to pass these parameters in to +the shader program. The implementation of each shader language (e.g., +Cg, GL2) defines its own mapping from Java 3D attribute to uniform +variable name.<br> +<br> +We need additional API to allow applications to pass in uniform +parameters that do not correspond to a pre-defined Java 3D +attribute...<br> TODO: Finish this...<br> +<br> +A partial list of Java 3D attributes that are mapped to shader +attributes follows: +</li> +<br> +<table style="text-align: left;" border="1" cellspacing="2" +cellpadding="2"> +<tbody> +<tr> +<td style="vertical-align: top; text-decoration: underline;">Java 3D +Attribute<br> +</td> +<td style="vertical-align: top; text-decoration: underline;">Cg +shader variable<br> +</td> +<td style="vertical-align: top; text-decoration: underline;">GL2 +shader variable<br> +</td> +</tr> +<tr> +<td style="vertical-align: top;">ModelViewProjection<br> +</td> +<td style="vertical-align: top;">glstate.matrix.mvp<br> +</td> +<td style="vertical-align: top;">gl_ModelViewProjectionMatrix<br> +</td> +</tr> +<tr> +<td style="vertical-align: top;">Light[<i>n</i>] pos<br> +</td> +<td style="vertical-align: top;">glstate.light[<i>n</i>].position </td> +<td style="vertical-align: top;">gl_LightSource[<i>n</i>].position </td> +</tr> +<tr> +<td style="vertical-align: top;">...<br> +</td> +<td style="vertical-align: top;">...<br> +</td> +<td style="vertical-align: top;">...<br> +</td> +</tr> +</tbody> +</table> +<br> +<li><b>Varying parameters</b> are those parameters that are specified +as per-vertex attributes. They are are interpolated across a primitive +similarly to colors and texture coordinates in the fixed function +pipeline.<br> +<br> +We need additional API to allow applications to pass in per-vertex +varying parameters...<br> TODO: Finish this...<br> +</li> +</ol> +<p>TODO: more info here. +</p> +</body> +</html> |