Class SoShaderObject
- java.lang.Object
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- com.openinventor.inventor.Inventor
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- com.openinventor.inventor.misc.SoBase
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- com.openinventor.inventor.fields.SoFieldContainer
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- com.openinventor.inventor.nodes.SoNode
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- com.openinventor.inventor.nodes.SoShaderObject
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- All Implemented Interfaces:
SafeDisposable
- Direct Known Subclasses:
SoComputeShader
,SoFragmentShader
,SoGeometryShader
,SoTessellationControlShader
,SoTessellationEvaluationShader
,SoVertexShader
public abstract class SoShaderObject extends SoNode
Abstract node class which defines a shader object. This abstract class is the parent of classes that define a vertex shader (SoVertexShader
), a geometry shader (SoGeometryShader
), a fragment shader (SoFragmentShader
), a tessellation control shader (SoTessellationControlShader
) or a tessellation evaluation shader (SoTessellationEvaluationShader
) program. (Tessellation shaders are supported since Open Inventor 9.3)There are five types of shaders that may be executed (in this order) in the rendering pipeline. Any one or all of these stages may be replaced by an application defined shader program.
- Vertex shader
The vertex shader is executed once for each vertex (usually in parallel). The purpose is to transform each vertex's 3D position in virtual space to the 2D coordinate at which it appears on the screen (as well as a depth value for the Z-buffer). Vertex shaders can manipulate properties such as position, color and texture coordinate, but cannot create new vertices. - Tessellation control shader
This shader accepts a list of vertices defining a patch from the vertex shader and controls the amount of tessellation applied to the patch. Following execution of this shader, a fixed tesselator computes a set of triangles in a parametric space. - Tessellation evaluation shader
This shader is executed at least once for each vertex that was created by the tesselator in the parametric space. The TES takes the parametric coordinate and the patch data output by the TCS to generate a final position for the surface. - Geometry shader
The geometry shader acts on a complete primitive (triangle or line): it can modify existing primitives, it can insert (create) new primitives, it can remove (destroy) existing primitives. - Fragment shader
Fragment shaders compute color and other attributes of each fragment.
Shader object nodes cannot be inserted directly in a scene graph. They must be added to the shaderObject field of an
SoShaderProgram
node.A shader object is defined by the following properties:
- Source program, which is the shader's source code (see
sourceProgram
field), - Uniform parameters set by the application (see
parameter
field), - State (active or not) (see
isActive
field).
The source program can be specified either by a string containing the program source code, or by a filename which contains the program source code. How the sourceProgram field is interpreted depends on the field
sourceType
. The shading languages accepted for the source program are OpenGL Shader Language (GLSL) , Cg from NVIDIA (see NOTE 1) and assembly language ( ARB_vertex_program, ARB_fragment_program). Generally GLSL is recommended because it works on any OpenGL hardware and is much higher level than the ARB commands.Uniform parameters can be set through the
parameter
field. Uniform means, in the case of a vertex or geometry program, a value which is the same for all vertices in a primitive, and, in the case of a fragment program, a value which is the same for all fragments created by a primitive. Each uniform parameter is represented by an instance of a specific subclass ofSoUniformShaderParameter
. For example, anSoShaderParameter1i
holds a single integer value. A uniform parameter has no effect if it is not valid, that is, if there is no corresponding name (identifier) in the CG/GLSL (ARB) source program. See NOTE 2 for info on retrieving a texture sampler uniform parameter within a GLSL program, an NVIDIA Cg fragment program, or an ARB_vertex_program/ARB_fragment_program program.A vertex shader can also use vertex parameters, which are per-vertex data passed from the application to the vertex shader. Vertex parameters are represented by an instance of a specific subclass of
SoVertexShaderParameter
. For example, anSoVertexShaderParameter1f
holds a set of floating point values and anSoVertexShaderParameter3f
holds a set ofSbVec3f
values. Vertex parameter nodes are property nodes (similar to materials or normals) and should be added directly in the scene graph, not in the shader object.Tips:
- When using GLSL shaders, set the environment variable OIV_GLSL_DEBUG to get the GLSL compile/link output in the console.
- If you set the environment variable OIV_SHADER_CHECK_INTERVAL, the shader source file is checked for a change every n seconds, where n is the value specified by the variable. This allows you to edit a shader source file without needing to restart your application after each shader modification.
NOTE 1: In case of Cg, the default profile used for the vertex shader is arbvp1, and arbfp1 for a fragment shader. However, we advise users to use the default profile because it enables you to retrieve the OpenGL state directly in your vertex/fragment program instead of passing the OpenGL state as uniform parameters, which could be inefficient in terms of performance. NOTE 2: With NVIDIA Cg and ARB_vertex_program/ARB_fragment_program, a texture sampler can be retrieved in your fragment program without specifying any SoShaderParameter
parameter.- With ARB_vertex_program/ARB_fragment_program, texture[i] corresponds to the texture sampler of unit i.
- With NVIDIA Cg, the first texture sampler parameter in your fragment program corresponds to the texture sampler of the texture unit 0, the second texture sampler parameter to the texture sampler of the texture unit 1, and so on.
Example:void main(// Inputs Input IN, uniform sampler2D rampDiffuse, // Texture sampler 2D of the texture unit 0 uniform sampler2D rampSpecular, // Texture sampler 2D of the texture unit 1 uniform sampler2D rampEdge, // Texture sampler 2D of the texture unit 2 ... - With GLSL, an
SoShaderParameter1i
must used for each texture sampler in order to specify the texture unit and texture sampler uniform parameter name pair.
NOTE 3: With Cg and ARB languages, at least the ARB_vertex_program and ARB_fragment_program, and with GLSL, at least GL_ARB_vertex_shader, GL_ARB_fragment_shader, and GL_ARB_shader_objects OpenGL extensions must be supported by your graphics board in order to be able to define a vertex shader and a fragment shader respectively. Otherwise no shader program will be executed.
NOTE 4: You should keep in mind that vertex and fragment programs modify the standard OpenGL pipeline.
- Vertex programs replace the following parts of the OpenGL graphics pipeline:
- Vertex transformation,
- Normal transformation normalization and rescaling,
- Lighting,
- Color material application,
- Clamping of colors,
- Texture coordinate generation,
- Texture coordinate transformation.
- But do not replace:
- Perspective divide and viewport mapping,
- Frustum and user clipping,
- Backface culling,
- Primitive assembly,
- Two sided lighting selection,
- Polygon offset,
- Polygon mode.
- Fragment programs replace the following parts of the OpenGL graphics pipeline:
- Operations on interpolated values,
- Pixel zoom,
- Texture access,
- Scale and bias,
- Texture application,
- Color table lookup,
- Fog convolution,
- Color sum,
- Color matrix.
- But do not replace:
- Shading model,
- Histogram,
- Coverage,
- Minmax,
- Pixel ownership test,
- Pixel packing and unpacking,
- Scissor,
- Stipple,
- Alpha test,
- Depth test,
- Stencil test,
- Alpha blending,
- Logical ops,
- Dithering,
- Plane masking.
File format/default:
This is an abstract class. See the reference page of a derived class for the format and default values.
EXAMPLE Simple fragment shader with one uniform parameter:
// Simple fragment shader with one uniform parameter // First load the fragment shader code SoFragmentShader fragmentShader = new SoFragmentShader(); fragmentShader.sourceProgram.setValue( "filename.glsl" ); // Set the shader parameter SoShaderParameter1i parameter = new SoShaderParameter1i(); parameter.name.setValue( "data1" ); parameter.value.setValue( 1 ); fragmentShader.parameter.set1Value( 0, parameter ); // Associate fragment shader with a shader program node SoShaderProgram shaderProgram = new SoShaderProgram(); shaderProgram.shaderObject.set1Value( 0, fragmentShader ); root.addChild(shaderProgram);
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
SoShaderObject.ShaderTypes
Type of the shader.static class
SoShaderObject.SourceTypes
Shader Object source type possible values.-
Nested classes/interfaces inherited from class com.openinventor.inventor.nodes.SoNode
SoNode.RenderModes
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Nested classes/interfaces inherited from class com.openinventor.inventor.Inventor
Inventor.ConstructorCommand
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Field Summary
Fields Modifier and Type Field Description SoSFBool
isActive
Specifies if the shader object is active or not.SoMFUniformShaderParameter
parameter
Contains the shader's uniform parameters.SoSFFilePathString
sourceProgram
Contains the shader object's source program, specified by a filename (sourceType
set toFILENAME
) or by the string containing the program (sourceType
set toARB_PROGRAM
,CG_PROGRAM
, orGLSL_PROGRAM
).SoSFEnum<SoShaderObject.SourceTypes>
sourceType
Specifies the shader object's source type.-
Fields inherited from class com.openinventor.inventor.Inventor
VERBOSE_LEVEL, ZeroHandle
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description SoShaderObject.ShaderTypes
getShaderType()
Must be redefined by derived class.-
Methods inherited from class com.openinventor.inventor.nodes.SoNode
affectsState, callback, copy, copy, distribute, doAction, getAlternateRep, getBoundingBox, getByName, getMatrix, getPrimitiveCount, getRenderEngineMode, getRenderUnitID, GLRender, GLRenderBelowPath, GLRenderInPath, GLRenderOffPath, grabEventsCleanup, grabEventsSetup, handleEvent, isBoundingBoxIgnoring, isOverride, pick, rayPick, search, setOverride, touch, write
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Methods inherited from class com.openinventor.inventor.fields.SoFieldContainer
copyFieldValues, copyFieldValues, enableNotify, fieldsAreEqual, get, getAllFields, getEventIn, getEventOut, getField, getFieldName, hasDefaultValues, isNotifyEnabled, set, setToDefaults
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Methods inherited from class com.openinventor.inventor.misc.SoBase
dispose, getName, isDisposable, isSynchronizable, setName, setSynchronizable
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Methods inherited from class com.openinventor.inventor.Inventor
getNativeResourceHandle
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Field Detail
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isActive
public final SoSFBool isActive
Specifies if the shader object is active or not.
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sourceType
public final SoSFEnum<SoShaderObject.SourceTypes> sourceType
Specifies the shader object's source type. The type of source can be either a filename containing the program (FILENAME
), or a string containing the source program (ARB_PROGRAM
,CG_PROGRAM
, orGLSL_PROGRAM
). Use enumSourceType
. Defaule is FILENAME.NOTE: The source type must be specified before the source program (
sourceProgram
) is specified.
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sourceProgram
public final SoSFFilePathString sourceProgram
Contains the shader object's source program, specified by a filename (sourceType
set toFILENAME
) or by the string containing the program (sourceType
set toARB_PROGRAM
,CG_PROGRAM
, orGLSL_PROGRAM
). If the filename is not an absolute path name, the list of directories maintained bySoInput
is searched. If the source program is not found in any of those directories, then the file is searched for relative to the directory from which theSoShaderObject
node was read.NOTE: The source type (
sourceType
) must be specified before the source program is specified.
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parameter
public final SoMFUniformShaderParameter parameter
Contains the shader's uniform parameters.
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Method Detail
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getShaderType
public SoShaderObject.ShaderTypes getShaderType()
Must be redefined by derived class.
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