GLSL Example Effect (COLLADA 1.4.1): Difference between revisions

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This document describes a simple example of the COLLADA profile_GLSL. The full listing can be found in the APPENDIX of this document. It is a complete example in that it includes geometry, textures, a scene, and a profile_GLSL effect. When rendered, the example should look like the following image.
This document describes a simple example of the COLLADA profile_GLSL. The full listing can be found in the APPENDIX of this document. It is a complete example in that it includes geometry, textures, a scene, and a profile_GLSL effect. When rendered, the example should look like the following image.


[[Image:Example.jpg]]


'''Figure 1: The example when rendered using the COLLADA OpenGL Effects Viewer.'''
'''Figure 1: The example when rendered using the COLLADA OpenGL Effects Viewer.'''
'''http://ati.amd.com/developer/rendermonkey/downloads.html'''
 
[http://ati.amd.com/developer/rendermonkey/downloads.html''' OpenGL Effect Viewer]


The following example uses the common COLLADA libraries, such as library_effects, library_materials, library_geometry, and library_images. Information on these libraries can be found elsewhere, this document focuses on the profile_GLSL only.  
The following example uses the common COLLADA libraries, such as library_effects, library_materials, library_geometry, and library_images. Information on these libraries can be found elsewhere, this document focuses on the profile_GLSL only.  
Line 20: Line 21:
The GLSL profile consists of the following main blocks:
The GLSL profile consists of the following main blocks:


* Code for the vertex and fragment shaders is contained within the <code> element.
* Code for the vertex and fragment shaders is contained within the <code> element
* Values for the shader parameters are defined using <newparams>.
* Values for the shader parameters are defined using <newparams>
* A Technique that defines an effect specific to a target platform (defined in <technique>)
* A Technique that defines an effect specific to a target platform (defined in <technique>)
* A List of passes (one or more) defined in the <pass> element.
* A List of passes (one or more) defined in the <pass> element
* Shader descriptions (<shader>).
* Shader descriptions (<shader>)
 


===The <code> element===
===The <code> element===
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  '''<code''' sid="Vertex_Program_E0_P0_VP">
  '''<code''' sid="Vertex_Program_E0_P0_VP">
uniform vec4 fvSpecular;
  uniform vec4 fvSpecular;
uniform vec4 fvDiffuse;
  uniform vec4 fvDiffuse;
uniform float fSpecularPower;
  uniform float fSpecularPower;
 
  uniform sampler2D baseMap;
uniform sampler2D baseMap;
  uniform sampler2D bumpMap;
uniform sampler2D bumpMap;
  varying vec2 Texcoord;
 
  varying vec3 ViewDirection;
varying vec2 Texcoord;
  varying vec3 LightDirection;
varying vec3 ViewDirection;
  void main( void )
varying vec3 LightDirection;
  <nowiki>{</nowiki>
 
  vec3 fvLightDirection = normalize( LightDirection );
void main( void )
  vec3 fvNormal = normalize( ( texture2D( bumpMap, Texcoord ).xyz <nowiki>*</nowiki> 2.0 ) - 1.0 );
<nowiki>{</nowiki>
  float fNDotL = dot( fvNormal, fvLightDirection );  
vec3 fvLightDirection = normalize( LightDirection );
  vec3 fvReflection = normalize( ( ( 2.0 <nowiki>*</nowiki> fvNormal ) <nowiki>*</nowiki> fNDotL ) - fvLightDirection );  
vec3 fvNormal = normalize( ( texture2D( bumpMap, Texcoord ).xyz <nowiki>*</nowiki> 2.0 ) - 1.0 );
  vec3 fvViewDirection = normalize( ViewDirection );
float fNDotL = dot( fvNormal, fvLightDirection );  
  float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) );
  vec4 fvBaseColor = texture2D( baseMap, Texcoord );
vec3 fvReflection = normalize( ( ( 2.0 <nowiki>*</nowiki> fvNormal ) <nowiki>*</nowiki> fNDotL ) - fvLightDirection );  
  vec4 fvTotalAmbient = fvAmbient <nowiki>*</nowiki> fvBaseColor;  
vec3 fvViewDirection = normalize( ViewDirection );
  vec4 fvTotalDiffuse = fvDiffuse <nowiki>*</nowiki> fNDotL <nowiki>*</nowiki> fvBaseColor;  
float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) );
  vec4 fvTotalSpecular = fvSpecular <nowiki>*</nowiki> ( pow( fRDotV, fSpecularPower ) );
  gl_FragColor = ( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular );
vec4 fvBaseColor = texture2D( baseMap, Texcoord );
  }
'''<nowiki></code></nowiki>'''
vec4 fvTotalAmbient = fvAmbient <nowiki>*</nowiki> fvBaseColor;  
vec4 fvTotalDiffuse = fvDiffuse <nowiki>*</nowiki> fNDotL <nowiki>*</nowiki> fvBaseColor;  
vec4 fvTotalSpecular = fvSpecular <nowiki>*</nowiki> ( pow( fRDotV, fSpecularPower ) );
gl_FragColor = ( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular );
<nowiki>}</nowiki>
'''</code>'''


===The <newparam> element===
===The <newparam> element===
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         '''<newparam '''sid="baseMap_Sampler">
         '''<newparam '''sid="baseMap_Sampler">
           <sampler2D>
           <sampler2D>
             <source>baseMap_Surface</source>
             <nowiki><source>baseMap_Surface</source></nowiki>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <magfilter>LINEAR</magfilter>
             <magfilter>LINEAR</magfilter>
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           </surface>
           </surface>
         </newparam>
         </newparam>


===The <technique> element===
===The <technique> element===


Techniques are a another layer of hierarchy inside profiles, each of which describes the same effect for a gradation of GPU hardware, API, or slight variations of the same effect e.g. different types of skin (cow, alligator, ostrich etc).
Techniques are a another layer of hierarchy inside profiles, each of which describes the same effect for a gradation of GPU hardware, API, or slight variations of the same effect e.g. different types of skin (cow, alligator, ostrich etc).
Line 101: Line 92:


           '''<pass''' sid="Pass_0">
           '''<pass''' sid="Pass_0">
             '''<shader''' stage="VERTEXPROGRAM">
             '''<shader''' stage="VERTEXPROGRAM">
               <compiler_target>110</compiler_target>
               <compiler_target>110</compiler_target>
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               </bind>
               </bind>
             '''</shader>'''
             '''</shader>'''
           '''</pass'''>
           '''</pass'''>
         '''</technique>'''
         '''</technique>'''
       '''</profile_GLSL>'''
       '''</profile_GLSL>'''
     </effect>
     </effect>


==  
== '''APPENDIX I: A complete profile_GLSL example'''==
APPENDIX I: A complete profile_GLSL example==




<COLLADA xmlns="http://www.collada.org/2005/11/COLLADASchema" version="1.4.1">
<COLLADA xmlns="http://www.collada.org/2005/11/COLLADASchema" version="1.4.1">
 
   <asset>
   <asset>
     <contributor>
     <contributor>
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     <up_axis>Y_UP</up_axis>
     <up_axis>Y_UP</up_axis>
   </asset>
   </asset>
   <library_visual_scenes>
   <library_visual_scenes>
     <visual_scene id="VisualSceneNode" name="untitled">
     <visual_scene id="VisualSceneNode" name="untitled">
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     </visual_scene>
     </visual_scene>
   </library_visual_scenes>
   </library_visual_scenes>
   <library_materials>
   <library_materials>
     <material id="Textured_Bump_E0_MP_MAT" name="Textured_Bump_E0_MP_MAT">
     <material id="Textured_Bump_E0_MP_MAT" name="Textured_Bump_E0_MP_MAT">
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         <setparam ref="baseMap_Sampler">
         <setparam ref="baseMap_Sampler">
           <sampler2D>
           <sampler2D>
             <source>baseMap_Surface</source>
             <nowiki><source>baseMap_Surface</source></nowiki>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <magfilter>LINEAR</magfilter>
             <magfilter>LINEAR</magfilter>
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         <setparam ref="bumpMap_Sampler">
         <setparam ref="bumpMap_Sampler">
           <sampler2D>
           <sampler2D>
             <source>bumpMap_Surface</source>
             <nowiki><source>bumpMap_Surface</source></nowiki>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <magfilter>LINEAR</magfilter>
             <magfilter>LINEAR</magfilter>
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     </material>
     </material>
   </library_materials>
   </library_materials>
   <library_effects>
   <library_effects>
     <effect id="Textured_Bump_E0_MP_FX">
     <effect id="Textured_Bump_E0_MP_FX">
       <profile_GLSL>
       <profile_GLSL>
         <code sid="Vertex_Program_E0_P0_VP">uniform vec3 fvLightPosition;
         <code sid="Vertex_Program_E0_P0_VP">
uniform vec3 fvEyePosition;
          uniform vec3 fvLightPosition;
 
          uniform vec3 fvEyePosition;
varying vec2 Texcoord;
          varying vec2 Texcoord;
varying vec3 ViewDirection;
          varying vec3 ViewDirection;
varying vec3 LightDirection;
          varying vec3 LightDirection;
          attribute vec3 rm_Binormal;
attribute vec3 rm_Binormal;
          attribute vec3 rm_Tangent;
attribute vec3 rm_Tangent;
          void main( void )
          {
void main( void )
          gl_Position = ftransform();
<nowiki>{</nowiki>
          Texcoord = gl_MultiTexCoord0.xy;
gl_Position = ftransform();
          vec4 fvObjectPosition = gl_ModelViewMatrix <nowiki>*</nowiki> gl_Vertex;
Texcoord = gl_MultiTexCoord0.xy;
          vec3 fvViewDirection = fvEyePosition - fvObjectPosition.xyz;
          vec3 fvLightDirection = fvLightPosition - fvObjectPosition.xyz;
vec4 fvObjectPosition = gl_ModelViewMatrix <nowiki>*</nowiki> gl_Vertex;
          vec3 fvNormal = gl_NormalMatrix <nowiki>*</nowiki> gl_Normal;
          vec3 fvBinormal = gl_NormalMatrix <nowiki>*</nowiki> rm_Binormal;
vec3 fvViewDirection = fvEyePosition - fvObjectPosition.xyz;
          vec3 fvTangent = gl_NormalMatrix <nowiki>*</nowiki> rm_Tangent;
vec3 fvLightDirection = fvLightPosition - fvObjectPosition.xyz;
          ViewDirection.x = dot( fvTangent, fvViewDirection );
          ViewDirection.y = dot( fvBinormal, fvViewDirection );
vec3 fvNormal = gl_NormalMatrix <nowiki>*</nowiki> gl_Normal;
          ViewDirection.z = dot( fvNormal, fvViewDirection );
vec3 fvBinormal = gl_NormalMatrix <nowiki>*</nowiki> rm_Binormal;
          LightDirection.x = dot( fvTangent, fvLightDirection.xyz );
vec3 fvTangent = gl_NormalMatrix <nowiki>*</nowiki> rm_Tangent;
          LightDirection.y = dot( fvBinormal, fvLightDirection.xyz );
          LightDirection.z = dot( fvNormal, fvLightDirection.xyz );
ViewDirection.x = dot( fvTangent, fvViewDirection );
          }
ViewDirection.y = dot( fvBinormal, fvViewDirection );
        <nowiki></code></nowiki>
ViewDirection.z = dot( fvNormal, fvViewDirection );
         <nowiki><code sid="Fragment_Program_E0_P0_FP"></nowiki>
          uniform vec4 fvAmbient;
LightDirection.x = dot( fvTangent, fvLightDirection.xyz );
          uniform vec4 fvSpecular;
LightDirection.y = dot( fvBinormal, fvLightDirection.xyz );
          uniform vec4 fvDiffuse;
LightDirection.z = dot( fvNormal, fvLightDirection.xyz );
          uniform float fSpecularPower;
          uniform sampler2D baseMap;
<nowiki>}</nowiki></code>
          uniform sampler2D bumpMap;
         <code sid="Fragment_Program_E0_P0_FP">uniform vec4 fvAmbient;
          varying vec2 Texcoord;
uniform vec4 fvSpecular;
          varying vec3 ViewDirection;
uniform vec4 fvDiffuse;
          varying vec3 LightDirection;
uniform float fSpecularPower;
          void main( void )
 
          {
uniform sampler2D baseMap;
            vec3 fvLightDirection = normalize( LightDirection );
uniform sampler2D bumpMap;
            vec3 fvNormal = normalize( ( texture2D( bumpMap, Texcoord ).xyz <nowiki>*</nowiki> 2.0 ) - 1.0 );
 
            float fNDotL = dot( fvNormal, fvLightDirection );  
varying vec2 Texcoord;
            vec3 fvReflection = normalize( ( ( 2.0 <nowiki>*</nowiki> fvNormal ) <nowiki>*</nowiki> fNDotL ) - fvLightDirection );  
varying vec3 ViewDirection;
            vec3 fvViewDirection = normalize( ViewDirection );
varying vec3 LightDirection;
            float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) );
 
            vec4 fvBaseColor = texture2D( baseMap, Texcoord );
void main( void )
            vec4 fvTotalAmbient = fvAmbient <nowiki>*</nowiki> fvBaseColor;  
<nowiki>{</nowiki>
            vec4 fvTotalDiffuse = fvDiffuse <nowiki>*</nowiki> fNDotL <nowiki>*</nowiki> fvBaseColor;  
vec3 fvLightDirection = normalize( LightDirection );
            vec4 fvTotalSpecular = fvSpecular <nowiki>*</nowiki> ( pow( fRDotV, fSpecularPower ) );
vec3 fvNormal = normalize( ( texture2D( bumpMap, Texcoord ).xyz <nowiki>*</nowiki> 2.0 ) - 1.0 );
            gl_FragColor = ( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular );
float fNDotL = dot( fvNormal, fvLightDirection );  
          }
        <nowiki></code></nowiki>
vec3 fvReflection = normalize( ( ( 2.0 <nowiki>*</nowiki> fvNormal ) <nowiki>*</nowiki> fNDotL ) - fvLightDirection );  
vec3 fvViewDirection = normalize( ViewDirection );
float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) );
vec4 fvBaseColor = texture2D( baseMap, Texcoord );
vec4 fvTotalAmbient = fvAmbient <nowiki>*</nowiki> fvBaseColor;  
vec4 fvTotalDiffuse = fvDiffuse <nowiki>*</nowiki> fNDotL <nowiki>*</nowiki> fvBaseColor;  
vec4 fvTotalSpecular = fvSpecular <nowiki>*</nowiki> ( pow( fRDotV, fSpecularPower ) );
gl_FragColor = ( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular );
<nowiki>}</nowiki></code>
         <newparam sid="fSpecularPower_E0_P0">
         <newparam sid="fSpecularPower_E0_P0">
           <float>25</float>
           <float>25</float>
Line 317: Line 287:
         <newparam sid="baseMap_Sampler">
         <newparam sid="baseMap_Sampler">
           <sampler2D>
           <sampler2D>
             <source>baseMap_Surface</source>
             <nowiki><source>baseMap_Surface</source></nowiki>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <magfilter>LINEAR</magfilter>
             <magfilter>LINEAR</magfilter>
Line 330: Line 300:
         <newparam sid="bumpMap_Sampler">
         <newparam sid="bumpMap_Sampler">
           <sampler2D>
           <sampler2D>
             <source>bumpMap_Surface</source>
             <nowiki><source>bumpMap_Surface</source></nowiki>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
             <magfilter>LINEAR</magfilter>
             <magfilter>LINEAR</magfilter>
Line 380: Line 350:
     </effect>
     </effect>
   </library_effects>
   </library_effects>
   <library_images>
   <library_images>
     <image id="base_E0" name="base_E0">
     <image id="base_E0" name="base_E0">
Line 389: Line 358:
     </image>
     </image>
   </library_images>
   </library_images>
   <library_geometries>
   <library_geometries>
     <geometry id="Model_E0_MESH_0_REF_1_lib" name="Model_E0_MESH_0_REF_1">
     <geometry id="Model_E0_MESH_0_REF_1_lib" name="Model_E0_MESH_0_REF_1">
       <mesh>
       <mesh>
         <source id="Model_E0_MESH_0_REF_1_lib_positions" name="position">
         <nowiki><source id="Model_E0_MESH_0_REF_1_lib_positions" name="position"></nowiki>
           <float_array id="Model_E0_MESH_0_REF_1_lib_positions_array" count="9">-50 -50 0 50 -50 0 0 50 0</float_array>
           <float_array id="Model_E0_MESH_0_REF_1_lib_positions_array" count="9">-50 -50 0 50 -50 0 0 50 0</float_array>
           <technique_common>
           <technique_common>
Line 403: Line 371:
           </technique_common>
           </technique_common>
         </source>
         </source>
         <source id="Model_E0_MESH_0_REF_1_lib_normals" name="normal">
         <nowiki><source id="Model_E0_MESH_0_REF_1_lib_normals" name="normal"></nowiki>
           <float_array id="Model_E0_MESH_0_REF_1_lib_normals_array" count="9">0 0 -1 0 0 -1 0 0 -1</float_array>
           <float_array id="Model_E0_MESH_0_REF_1_lib_normals_array" count="9">0 0 -1 0 0 -1 0 0 -1</float_array>
           <technique_common>
           <technique_common>
Line 413: Line 381:
           </technique_common>
           </technique_common>
         </source>
         </source>
         <source id="Model_E0_MESH_0_REF_1_lib_texcoords" name="texcoords">
         <nowiki><source id="Model_E0_MESH_0_REF_1_lib_texcoords" name="texcoords"></nowiki>
           <float_array id="Model_E0_MESH_0_REF_1_lib_texcoords_array" count="6">0 0 1 0 0.5 1</float_array>
           <float_array id="Model_E0_MESH_0_REF_1_lib_texcoords_array" count="6">0 0 1 0 0.5 1</float_array>
           <technique_common>
           <technique_common>
Line 422: Line 390:
           </technique_common>
           </technique_common>
         </source>
         </source>
         <source id="Model_E0_MESH_0_REF_1_lib_tangents" name="tangent">
         <nowiki><source id="Model_E0_MESH_0_REF_1_lib_tangents" name="tangent"></nowiki>
           <float_array id="Model_E0_MESH_0_REF_1_lib_tangents_array" count="9">1 0 0 1 0 0 1 0 0</float_array>
           <float_array id="Model_E0_MESH_0_REF_1_lib_tangents_array" count="9">1 0 0 1 0 0 1 0 0</float_array>
           <technique_common>
           <technique_common>
Line 432: Line 400:
           </technique_common>
           </technique_common>
         </source>
         </source>
         <source id="Model_E0_MESH_0_REF_1_lib_binormals" name="binormal">
         <nowiki><source id="Model_E0_MESH_0_REF_1_lib_binormals" name="binormal"></nowiki>
           <float_array id="Model_E0_MESH_0_REF_1_lib_binormals_array" count="9">0 1 0 0 0 0 0 1 0</float_array>
           <float_array id="Model_E0_MESH_0_REF_1_lib_binormals_array" count="9">0 1 0 0 0 0 0 1 0</float_array>
           <technique_common>
           <technique_common>
Line 451: Line 419:
           <input offset="0" semantic="TANGENT" source="<nowiki>#</nowiki>Model_E0_MESH_0_REF_1_lib_tangents"></input>
           <input offset="0" semantic="TANGENT" source="<nowiki>#</nowiki>Model_E0_MESH_0_REF_1_lib_tangents"></input>
           <input offset="0" semantic="BINORMAL" source="<nowiki>#</nowiki>Model_E0_MESH_0_REF_1_lib_binormals"></input>
           <input offset="0" semantic="BINORMAL" source="<nowiki>#</nowiki>Model_E0_MESH_0_REF_1_lib_binormals"></input>
          <p>0 1 2</p>
          <nowiki><p>0 1 2</p></nowiki>
         </triangles>
         </triangles>
       </mesh>
       </mesh>
     </geometry>
     </geometry>
   </library_geometries>
   </library_geometries>
   <scene>
   <scene>
     <instance_visual_scene url="<nowiki>#</nowiki>VisualSceneNode"></instance_visual_scene>
     <instance_visual_scene url="<nowiki>#</nowiki>VisualSceneNode"></instance_visual_scene>
   </scene>
   </scene>
</COLLADA>


</COLLADA>
[[Category:COLLADA tutorials]]

Latest revision as of 08:58, 26 May 2012

An example of a Profile GLSL effect

This document describes a simple example of the COLLADA profile_GLSL. The full listing can be found in the APPENDIX of this document. It is a complete example in that it includes geometry, textures, a scene, and a profile_GLSL effect. When rendered, the example should look like the following image.

Figure 1: The example when rendered using the COLLADA OpenGL Effects Viewer.

OpenGL Effect Viewer

The following example uses the common COLLADA libraries, such as library_effects, library_materials, library_geometry, and library_images. Information on these libraries can be found elsewhere, this document focuses on the profile_GLSL only.

Structure of the GLSL Profile

The start of the profile_GLSL is indicated within the <effect> element using the <profile_GLSL> element. 

<library_effects>
   <effect id="Textured_Bump_E0_MP_FX">
     <profile_GLSL>

The GLSL profile consists of the following main blocks:

  • Code for the vertex and fragment shaders is contained within the element
  • Values for the shader parameters are defined using <newparams>
  • A Technique that defines an effect specific to a target platform (defined in <technique>)
  • A List of passes (one or more) defined in the <pass> element
  • Shader descriptions (<shader>)

The element

The following is a typical GLSL element containing GLSL shader code (marked in green). There are usually two elements, one for the vertex shader and one for the fragment shader. The GLSL shading language is not described here. 

<code sid="Vertex_Program_E0_P0_VP">
  uniform vec4 fvSpecular;
  uniform vec4 fvDiffuse;
  uniform float fSpecularPower;
  uniform sampler2D baseMap;
  uniform sampler2D bumpMap;
  varying vec2 Texcoord;
  varying vec3 ViewDirection;
  varying vec3 LightDirection;
  void main( void )
  {
  vec3 fvLightDirection = normalize( LightDirection );
  vec3 fvNormal = normalize( ( texture2D( bumpMap, Texcoord ).xyz * 2.0 ) - 1.0 );
  float fNDotL = dot( fvNormal, fvLightDirection ); 
  vec3 fvReflection = normalize( ( ( 2.0 * fvNormal ) * fNDotL ) - fvLightDirection ); 
  vec3 fvViewDirection = normalize( ViewDirection );
  float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) );
  vec4 fvBaseColor = texture2D( baseMap, Texcoord );
  vec4 fvTotalAmbient = fvAmbient * fvBaseColor; 
  vec4 fvTotalDiffuse = fvDiffuse * fNDotL * fvBaseColor; 
  vec4 fvTotalSpecular = fvSpecular * ( pow( fRDotV, fSpecularPower ) );
  gl_FragColor = ( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular );
  }
</code>

The <newparam> element

Newparams are used to define data that needs to be bound to the uniforms in the shader code. In the following examples we can see that newparams for specular power, sampler data and surface data are set. Please note that these values can be overridden at the <material> level by using <setparam>‘s. 

       <newparam sid="fSpecularPower_E0_P0">
         <float>25</float>
       </newparam>

       <newparam sid="baseMap_Sampler">
         <sampler2D>
           <source>baseMap_Surface</source>
           <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
           <magfilter>LINEAR</magfilter>
         </sampler2D>
       </newparam>

       <newparam sid="baseMap_Surface">
         <surface type="2D">
           <init_from>base_E0</init_from>
           <format>A8R8G8B8</format>
         </surface>
       </newparam>

The <technique> element

Techniques are a another layer of hierarchy inside profiles, each of which describes the same effect for a gradation of GPU hardware, API, or slight variations of the same effect e.g. different types of skin (cow, alligator, ostrich etc).

<technique sid="Textured_Bump_E0_MP_TECH">

The <pass> and <shader> elements

At the core of an effect description are the <pass> elements. Each pass element specifies the target compiler, references to the vertex or fragment shader programs (with code entry points), and a set of input bindings for the shader parameters.

In the following example we show a pass element with the two shader stages (vertex and fragment). Each shader stage binds the params to the uniforms within tha shader code. Notice that the params do not actually define any data - just the reference to a previously defined newparam. 

         <pass sid="Pass_0">
           <shader stage="VERTEXPROGRAM">
             <compiler_target>110</compiler_target>
             <name source="Vertex_Program_E0_P0_VP">main</name>
             <bind symbol="fvEyePosition">
               <param ref="fvEyePosition_E0_P0"></param>
             </bind>
             <bind symbol="fvLightPosition">
               <param ref="fvLightPosition_E0_P0"></param>
             </bind>
           </shader>
           <shader stage="FRAGMENTPROGRAM">
             <compiler_target>110</compiler_target>
             <name source="Fragment_Program_E0_P0_FP">main</name>
             <bind symbol="fSpecularPower">
               <param ref="fSpecularPower_E0_P0"></param>
             </bind>
             <bind symbol="fvAmbient">
               <param ref="fvAmbient_E0_P0"></param>
             </bind>
             <bind symbol="fvDiffuse">
               <param ref="fvDiffuse_E0_P0"></param>
             </bind>
             <bind symbol="fvSpecular">
               <param ref="fvSpecular_E0_P0"></param>
             </bind>
             <bind symbol="baseMap">
               <param ref="baseMap_Sampler"></param>
             </bind>
             <bind symbol="bumpMap">
               <param ref="bumpMap_Sampler"></param>
             </bind>
           </shader>
         </pass>
       </technique>
     </profile_GLSL>
   </effect>

APPENDIX I: A complete profile_GLSL example

<COLLADA xmlns="http://www.collada.org/2005/11/COLLADASchema" version="1.4.1">
 <asset>
   <contributor>
     <author></author>
     <authoring_tool>RenderMonkey</authoring_tool>
     <comments>Output from RenderMonkey COLLADA Exporter</comments>
     <copyright></copyright>
     <source_data></source_data>
   </contributor>
   <created>2007-12-11T14:24:00Z</created>
   <modified>2007-12-11T14:24:00Z</modified>
   <unit meter="0.01" name="centimeter"></unit>
   <up_axis>Y_UP</up_axis>
 </asset>
 <library_visual_scenes>
   <visual_scene id="VisualSceneNode" name="untitled">
     <node id="Model_E0_MESH_0_REF_1" name="Model_E0_MESH_0_REF_1">
       <instance_geometry url="#Model_E0_MESH_0_REF_1_lib">
         <bind_material>
           <technique_common>
             <instance_material symbol="Textured_Bump_E0_MP_MAT" target="#Textured_Bump_E0_MP_MAT">
               <bind_vertex_input semantic="rm_Binormal" input_semantic="BINORMAL" input_set="2"></bind_vertex_input>
               <bind_vertex_input semantic="rm_Tangent" input_semantic="TANGENT" input_set="1"></bind_vertex_input>
             </instance_material>
           </technique_common>
         </bind_material>
       </instance_geometry>
     </node>
   </visual_scene>
 </library_visual_scenes>
 <library_materials>
   <material id="Textured_Bump_E0_MP_MAT" name="Textured_Bump_E0_MP_MAT">
     <instance_effect url="#Textured_Bump_E0_MP_FX">
       <technique_hint platform="PC-OGL" profile="GLSL" ref="Textured_Bump_E0_MP_TECH"></technique_hint>
       <setparam ref="fSpecularPower_E0_P0">
         <float>25</float>
       </setparam>
       <setparam ref="fvAmbient_E0_P0">
         <float4>0.368627 0.368421 0.368421 1</float4>
       </setparam>
       <setparam ref="fvDiffuse_E0_P0">
         <float4>0.886275 0.885003 0.885003 1</float4>
       </setparam>
       <setparam ref="fvEyePosition_E0_P0">
         <float3>0 0 100</float3>
       </setparam>
       <setparam ref="fvLightPosition_E0_P0">
         <float3>-100 100 100</float3>
       </setparam>
       <setparam ref="fvSpecular_E0_P0">
         <float4>0.490196 0.488722 0.488722 1</float4>
       </setparam>
       <setparam ref="baseMap_Sampler">
         <sampler2D>
           <source>baseMap_Surface</source>
           <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
           <magfilter>LINEAR</magfilter>
         </sampler2D>
       </setparam>
       <setparam ref="baseMap_Surface">
         <surface type="2D">
           <init_from>base_E0</init_from>
           <format>A8R8G8B8</format>
         </surface>
       </setparam>
       <setparam ref="bumpMap_Sampler">
         <sampler2D>
           <source>bumpMap_Surface</source>
           <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
           <magfilter>LINEAR</magfilter>
         </sampler2D>
       </setparam>
       <setparam ref="bumpMap_Surface">
         <surface type="2D">
           <init_from>bump_E0</init_from>
           <format>A8R8G8B8</format>
         </surface>
       </setparam>
     </instance_effect>
   </material>
 </library_materials>
 <library_effects>
   <effect id="Textured_Bump_E0_MP_FX">
     <profile_GLSL>
       
         uniform vec3 fvLightPosition;
         uniform vec3 fvEyePosition;
         varying vec2 Texcoord;
         varying vec3 ViewDirection;
         varying vec3 LightDirection;
         attribute vec3 rm_Binormal;
         attribute vec3 rm_Tangent;
         void main( void )
         {
          gl_Position = ftransform();
          Texcoord = gl_MultiTexCoord0.xy;
          vec4 fvObjectPosition = gl_ModelViewMatrix * gl_Vertex;
          vec3 fvViewDirection = fvEyePosition - fvObjectPosition.xyz;
          vec3 fvLightDirection = fvLightPosition - fvObjectPosition.xyz;
          vec3 fvNormal = gl_NormalMatrix * gl_Normal;
          vec3 fvBinormal = gl_NormalMatrix * rm_Binormal;
          vec3 fvTangent = gl_NormalMatrix * rm_Tangent;
          ViewDirection.x = dot( fvTangent, fvViewDirection );
          ViewDirection.y = dot( fvBinormal, fvViewDirection );
          ViewDirection.z = dot( fvNormal, fvViewDirection );
          LightDirection.x = dot( fvTangent, fvLightDirection.xyz );
          LightDirection.y = dot( fvBinormal, fvLightDirection.xyz );
          LightDirection.z = dot( fvNormal, fvLightDirection.xyz );
          }
       </code>
       <code sid="Fragment_Program_E0_P0_FP">
         uniform vec4 fvAmbient;
         uniform vec4 fvSpecular;
         uniform vec4 fvDiffuse;
         uniform float fSpecularPower;
         uniform sampler2D baseMap;
         uniform sampler2D bumpMap;
         varying vec2 Texcoord;
         varying vec3 ViewDirection;
         varying vec3 LightDirection;
         void main( void )
         {
           vec3 fvLightDirection = normalize( LightDirection );
           vec3 fvNormal = normalize( ( texture2D( bumpMap, Texcoord ).xyz * 2.0 ) - 1.0 );
           float fNDotL = dot( fvNormal, fvLightDirection ); 
           vec3 fvReflection = normalize( ( ( 2.0 * fvNormal ) * fNDotL ) - fvLightDirection ); 
           vec3 fvViewDirection = normalize( ViewDirection );
           float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) );
           vec4 fvBaseColor = texture2D( baseMap, Texcoord );
           vec4 fvTotalAmbient = fvAmbient * fvBaseColor; 
           vec4 fvTotalDiffuse = fvDiffuse * fNDotL * fvBaseColor; 
           vec4 fvTotalSpecular = fvSpecular * ( pow( fRDotV, fSpecularPower ) );
           gl_FragColor = ( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular );
         }
       </code>
       <newparam sid="fSpecularPower_E0_P0">
         <float>25</float>
       </newparam>
       <newparam sid="fvAmbient_E0_P0">
         <float4>0.368627 0.368421 0.368421 1</float4>
       </newparam>
       <newparam sid="fvDiffuse_E0_P0">
         <float4>0.886275 0.885003 0.885003 1</float4>
       </newparam>
       <newparam sid="fvEyePosition_E0_P0">
         <float3>0 0 100</float3>
       </newparam>
       <newparam sid="fvLightPosition_E0_P0">
         <float3>-100 100 100</float3>
       </newparam>
       <newparam sid="fvSpecular_E0_P0">
         <float4>0.490196 0.488722 0.488722 1</float4>
       </newparam>
       <newparam sid="baseMap_Sampler">
         <sampler2D>
           <source>baseMap_Surface</source>
           <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
           <magfilter>LINEAR</magfilter>
         </sampler2D>
       </newparam>
       <newparam sid="baseMap_Surface">
         <surface type="2D">
           <init_from>base_E0</init_from>
           <format>A8R8G8B8</format>
         </surface>
       </newparam>
       <newparam sid="bumpMap_Sampler">
         <sampler2D>
           <source>bumpMap_Surface</source>
           <minfilter>LINEAR_MIPMAP_LINEAR</minfilter>
           <magfilter>LINEAR</magfilter>
         </sampler2D>
       </newparam>
       <newparam sid="bumpMap_Surface">
         <surface type="2D">
           <init_from>bump_E0</init_from>
           <format>A8R8G8B8</format>
         </surface>
       </newparam>
       <technique sid="Textured_Bump_E0_MP_TECH">
         <pass sid="Pass_0">
           <shader stage="VERTEXPROGRAM">
             <compiler_target>110</compiler_target>
             <name source="Vertex_Program_E0_P0_VP">main</name>
             <bind symbol="fvEyePosition">
               <param ref="fvEyePosition_E0_P0"></param>
             </bind>
             <bind symbol="fvLightPosition">
               <param ref="fvLightPosition_E0_P0"></param>
             </bind>
           </shader>
           <shader stage="FRAGMENTPROGRAM">
             <compiler_target>110</compiler_target>
             <name source="Fragment_Program_E0_P0_FP">main</name>
             <bind symbol="fSpecularPower">
               <param ref="fSpecularPower_E0_P0"></param>
             </bind>
             <bind symbol="fvAmbient">
               <param ref="fvAmbient_E0_P0"></param>
             </bind>
             <bind symbol="fvDiffuse">
               <param ref="fvDiffuse_E0_P0"></param>
             </bind>
             <bind symbol="fvSpecular">
               <param ref="fvSpecular_E0_P0"></param>
             </bind>
             <bind symbol="baseMap">
               <param ref="baseMap_Sampler"></param>
             </bind>
             <bind symbol="bumpMap">
               <param ref="bumpMap_Sampler"></param>
             </bind>
           </shader>
         </pass>
       </technique>
     </profile_GLSL>
   </effect>
 </library_effects>
 <library_images>
   <image id="base_E0" name="base_E0">
     <init_from>./Textured_Bump/Fieldstone.tga</init_from>
   </image>
   <image id="bump_E0" name="bump_E0">
     <init_from>./Textured_Bump/FieldstoneBumpDOT3.tga</init_from>
   </image>
 </library_images>
 <library_geometries>
   <geometry id="Model_E0_MESH_0_REF_1_lib" name="Model_E0_MESH_0_REF_1">
     <mesh>
       <source id="Model_E0_MESH_0_REF_1_lib_positions" name="position">
         <float_array id="Model_E0_MESH_0_REF_1_lib_positions_array" count="9">-50 -50 0 50 -50 0 0 50 0</float_array>
         <technique_common>
           <accessor count="3" source="#Model_E0_MESH_0_REF_1_lib_positions_array" stride="3">
             <param name="X" type="float"></param>
             <param name="Y" type="float"></param>
             <param name="Z" type="float"></param>
           </accessor>
         </technique_common>
       </source>
       <source id="Model_E0_MESH_0_REF_1_lib_normals" name="normal">
         <float_array id="Model_E0_MESH_0_REF_1_lib_normals_array" count="9">0 0 -1 0 0 -1 0 0 -1</float_array>
         <technique_common>
           <accessor count="3" source="#Model_E0_MESH_0_REF_1_lib_normals_array" stride="3">
             <param name="X" type="float"></param>
             <param name="Y" type="float"></param>
             <param name="Z" type="float"></param>
           </accessor>
         </technique_common>
       </source>
       <source id="Model_E0_MESH_0_REF_1_lib_texcoords" name="texcoords">
         <float_array id="Model_E0_MESH_0_REF_1_lib_texcoords_array" count="6">0 0 1 0 0.5 1</float_array>
         <technique_common>
           <accessor count="3" source="#Model_E0_MESH_0_REF_1_lib_texcoords_array" stride="2">
             <param name="X" type="float"></param>
             <param name="Y" type="float"></param>
           </accessor>
         </technique_common>
       </source>
       <source id="Model_E0_MESH_0_REF_1_lib_tangents" name="tangent">
         <float_array id="Model_E0_MESH_0_REF_1_lib_tangents_array" count="9">1 0 0 1 0 0 1 0 0</float_array>
         <technique_common>
           <accessor count="3" source="#Model_E0_MESH_0_REF_1_lib_tangents_array" stride="3">
             <param name="X" type="float"></param>
             <param name="Y" type="float"></param>
             <param name="Z" type="float"></param>
           </accessor>
         </technique_common>
       </source>
       <source id="Model_E0_MESH_0_REF_1_lib_binormals" name="binormal">
         <float_array id="Model_E0_MESH_0_REF_1_lib_binormals_array" count="9">0 1 0 0 0 0 0 1 0</float_array>
         <technique_common>
           <accessor count="3" source="#Model_E0_MESH_0_REF_1_lib_binormals_array" stride="3">
             <param name="X" type="float"></param>
             <param name="Y" type="float"></param>
             <param name="Z" type="float"></param>
           </accessor>
         </technique_common>
       </source>
       <vertices id="Model_E0_MESH_0_REF_1_lib_vertices">
         <input semantic="POSITION" source="#Model_E0_MESH_0_REF_1_lib_positions"></input>
         <input semantic="NORMAL" source="#Model_E0_MESH_0_REF_1_lib_normals"></input>
         <input semantic="TEXCOORD" source="#Model_E0_MESH_0_REF_1_lib_texcoords"></input>
       </vertices>
       <triangles count="1" material="Textured_Bump_E0_MP_MAT">
         <input offset="0" semantic="VERTEX" source="#Model_E0_MESH_0_REF_1_lib_vertices"></input>
         <input offset="0" semantic="TANGENT" source="#Model_E0_MESH_0_REF_1_lib_tangents"></input>
         <input offset="0" semantic="BINORMAL" source="#Model_E0_MESH_0_REF_1_lib_binormals"></input>
          <p>0 1 2</p>
       </triangles>
     </mesh>
   </geometry>
 </library_geometries>
 <scene>
   <instance_visual_scene url="#VisualSceneNode"></instance_visual_scene>
 </scene>
</COLLADA>
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