Shaders¶

GpuShaderCreator¶

class PyOpenColorIO.GpuShaderCreator¶

Inherit from the class to fully customize the implementation of a GPU shader program from a color transformation.

When no customizations are needed then the GpuShaderDesc is a better choice.

To better decouple the DynamicProperties from their GPU implementation, the code provides several addUniform() methods i.e. one per access function types. For example, an ExposureContrastTransform instance owns three DynamicProperties and they are all implemented by a double. When creating the GPU fragment shader program, the addUniform() with GpuShaderCreator::DoubleGetter is called when property is dynamic, up to three times.

An OCIO shader program could contain:

A declaration part e.g., uniform sampled3D tex3;
Some helper methods
The OCIO shader function may be broken down as:
The function header e.g., void OCIODisplay(in vec4 inColor) {
The function body e.g., vec4 outColor.rgb = texture3D(tex3, inColor.rgb).rgb;
The function footer e.g., return outColor; }

Usage Example:

Below is a code snippet to highlight the different parts of the OCIO shader program.

// All global declarations
uniform sampled3D tex3;

// All helper methods
vec3 computePosition(vec3 color)
{
   vec3 coords = color;
   // Some processing...
   return coords;
}

// The shader function
vec4 OCIODisplay(in vec4 inColor)     //
{                                     // Function Header
   vec4 outColor = inColor;           //

   outColor.rgb = texture3D(tex3, computePosition(inColor.rgb)).rgb;

   return outColor;                   // Function Footer
}                                     //

addToDeclareShaderCode(shaderCode: str) → None¶

addToFunctionFooterShaderCode(shaderCode: str) → None¶

addToFunctionHeaderShaderCode(shaderCode: str) → None¶

addToFunctionShaderCode(shaderCode: str) → None¶

addToHelperShaderCode(shaderCode: str) → None¶

begin(uid: str) → None¶: Start to collect the shader data.

clone() → PyOpenColorIO.GpuShaderCreator ¶

createShaderText(shaderDeclarations: str, shaderHelperMethods: str, shaderFunctionHeader: str, shaderFunctionBody: str, shaderFunctionFooter: str) → None¶: Create the OCIO shader program.

Note

The OCIO shader program is decomposed to allow a specific implementation to change some parts. Some product integrations add the color processing within a client shader program, imposing constraints requiring this flexibility.

end() → None¶: End to collect the shader data.

finalize() → None¶

getCacheID() → str¶

getDynamicProperties() → PyOpenColorIO.GpuShaderCreator.DynamicPropertyIterator ¶

getDynamicProperty(type: PyOpenColorIO.DynamicPropertyType) → PyOpenColorIO.DynamicProperty ¶

getFunctionName() → str¶

getLanguage() → PyOpenColorIO.GpuLanguage ¶

getNextResourceIndex() → int¶: To avoid texture/unform name clashes always append an increasing number to the resource name.

getPixelName() → str¶

getResourcePrefix() → str¶: Note

Some applications require that textures, uniforms, and helper methods be uniquely named because several processor instances could coexist.

getTextureMaxWidth() → int¶

getUniqueID() → str¶

hasDynamicProperty(type: PyOpenColorIO.DynamicPropertyType) → bool¶

setFunctionName(name: str) → None¶

setLanguage(language: PyOpenColorIO.GpuLanguage) → None¶: Set the shader program language.

setPixelName(name: str) → None¶: Set the pixel name variable holding the color values.

setResourcePrefix(prefix: str) → None¶: Set a prefix to the resource name.

setTextureMaxWidth(maxWidth: int) → None¶: Some graphic cards could have 1D & 2D textures with size limitations.

setUniqueID(uid: str) → None¶

class PyOpenColorIO.GpuShaderCreator.TextureType¶

Members:

TEXTURE_RED_CHANNEL

TEXTURE_RGB_CHANNEL

property name → str¶

TEXTURE_RED_CHANNEL = <TextureType.TEXTURE_RED_CHANNEL: 0>¶

TEXTURE_RGB_CHANNEL = <TextureType.TEXTURE_RGB_CHANNEL: 1>¶

class PyOpenColorIO.GpuShaderCreator.DynamicPropertyIterator¶

self[arg0: int] → PyOpenColorIO.DynamicProperty ¶

iter(self) → PyOpenColorIO.GpuShaderCreator.DynamicPropertyIterator ¶

len(self) → int¶

next(self) → PyOpenColorIO.DynamicProperty ¶

class OpenColorIO_v2_1dev::GpuShaderCreator¶

Inherit from the class to fully customize the implementation of a GPU shader program from a color transformation.

When no customizations are needed then the GpuShaderDesc is a better choice.

To better decouple the DynamicProperties from their GPU implementation, the code provides several addUniform() methods i.e. one per access function types. For example, an ExposureContrastTransform instance owns three DynamicProperties and they are all implemented by a double. When creating the GPU fragment shader program, the addUniform() with GpuShaderCreator::DoubleGetter is called when property is dynamic, up to three times.

An OCIO shader program could contain:

A declaration part e.g., uniform sampled3D tex3;
Some helper methods
The OCIO shader function may be broken down as:
- The function header e.g., void OCIODisplay(in vec4 inColor) {
- The function body e.g., vec4 outColor.rgb = texture3D(tex3, inColor.rgb).rgb;
- The function footer e.g., return outColor; }

Usage Example:

Below is a code snippet to highlight the different parts of the OCIO shader program.

// All global declarations
uniform sampled3D tex3;

// All helper methods
vec3 computePosition(vec3 color)
{
   vec3 coords = color;
   // Some processing...
   return coords;
}

// The shader function
vec4 OCIODisplay(in vec4 inColor)     //
{                                     // Function Header
   vec4 outColor = inColor;           //

   outColor.rgb = texture3D(tex3, computePosition(inColor.rgb)).rgb;

   return outColor;                   // Function Footer
}                                     //

Subclassed by GpuShaderDesc

Public Types

enum TextureType¶

Values:

enumerator TEXTURE_RED_CHANNEL¶: Only use the red channel of the texture.

enumerator TEXTURE_RGB_CHANNEL¶

typedef std::function<double()> DoubleGetter¶: Function returning a double, used by uniforms. GPU converts double to float.

typedef std::function<bool()> BoolGetter¶: Function returning a bool, used by uniforms.

typedef std::function<const Float3&()> Float3Getter¶: Functions returning a Float3, used by uniforms.

typedef std::function<int()> SizeGetter¶: Function returning an int, used by uniforms.

typedef std::function<const float*()> VectorFloatGetter¶: Function returning a float *, used by uniforms.

typedef std::function<const int*()> VectorIntGetter¶: Function returning an int *, used by uniforms.

Public Functions

virtual GpuShaderCreatorRcPtr clone() const = 0¶

const char *getUniqueID() const noexcept¶

void setUniqueID(const char *uid) noexcept¶

GpuLanguage getLanguage() const noexcept¶

void setLanguage(GpuLanguage lang) noexcept¶: Set the shader program language.

const char *getFunctionName() const noexcept¶

void setFunctionName(const char *name) noexcept¶

const char *getPixelName() const noexcept¶

void setPixelName(const char *name) noexcept¶: Set the pixel name variable holding the color values.

const char *getResourcePrefix() const noexcept¶

Note: Some applications require that textures, uniforms, and helper methods be uniquely named because several processor instances could coexist.

void setResourcePrefix(const char *prefix) noexcept¶: Set a prefix to the resource name.

virtual const char *getCacheID() const noexcept¶

virtual void begin(const char *uid)¶: Start to collect the shader data.

virtual void end()¶: End to collect the shader data.

virtual void setTextureMaxWidth(unsigned maxWidth) = 0¶: Some graphic cards could have 1D & 2D textures with size limitations.

virtual unsigned getTextureMaxWidth() const noexcept = 0¶

unsigned getNextResourceIndex() noexcept¶: To avoid texture/unform name clashes always append an increasing number to the resource name.

virtual bool addUniform(const char *name, const DoubleGetter &getDouble) = 0¶

virtual bool addUniform(const char *name, const BoolGetter &getBool) = 0¶

virtual bool addUniform(const char *name, const Float3Getter &getFloat3) = 0¶

virtual bool addUniform(const char *name, const SizeGetter &getSize, const VectorFloatGetter &getVectorFloat) = 0¶

virtual bool addUniform(const char *name, const SizeGetter &getSize, const VectorIntGetter &getVectorInt) = 0¶

void addDynamicProperty(DynamicPropertyRcPtr &prop)¶: Adds the property (used internally).

unsigned getNumDynamicProperties() const noexcept¶: Dynamic Property related methods.

DynamicPropertyRcPtr getDynamicProperty(unsigned index) const¶

bool hasDynamicProperty(DynamicPropertyType type) const¶

DynamicPropertyRcPtr getDynamicProperty(DynamicPropertyType type) const¶: Dynamic properties allow changes once the fragment shader program has been created. The steps are to get the appropriate DynamicProperty instance, and then change its value.

virtual void addTexture(const char *textureName, const char *samplerName, unsigned width, unsigned height, TextureType channel, Interpolation interpolation, const float *values) = 0¶

virtual void add3DTexture(const char *textureName, const char *samplerName, unsigned edgelen, Interpolation interpolation, const float *values) = 0¶

virtual void addToDeclareShaderCode(const char *shaderCode)¶

virtual void addToHelperShaderCode(const char *shaderCode)¶

virtual void addToFunctionHeaderShaderCode(const char *shaderCode)¶

virtual void addToFunctionShaderCode(const char *shaderCode)¶

virtual void addToFunctionFooterShaderCode(const char *shaderCode)¶

virtual void createShaderText(const char *shaderDeclarations, const char *shaderHelperMethods, const char *shaderFunctionHeader, const char *shaderFunctionBody, const char *shaderFunctionFooter)¶

Create the OCIO shader program.

Note: The OCIO shader program is decomposed to allow a specific implementation to change some parts. Some product integrations add the color processing within a client shader program, imposing constraints requiring this flexibility.

virtual void finalize()¶

GpuShaderCreator(const GpuShaderCreator&) = delete¶

GpuShaderCreator &operator=(const GpuShaderCreator&) = delete¶

virtual ~GpuShaderCreator()¶: Do not use (needed only for pybind11).

typedef std::shared_ptr<const GpuShaderCreator> OpenColorIO_v2_1dev::ConstGpuShaderCreatorRcPtr¶

typedef std::shared_ptr<GpuShaderCreator> OpenColorIO_v2_1dev::GpuShaderCreatorRcPtr¶

GpuShaderDesc¶

class PyOpenColorIO.GpuShaderDesc¶

This class holds the GPU-related information needed to build a shader program from a specific processor.

This class defines the interface and there are two implementations provided. The “legacy” mode implements the OCIO v1 approach of baking certain ops in order to have at most one 3D-LUT. The “generic” mode is the v2 default and allows all the ops to be processed as-is, without baking, like the CPU renderer. Custom implementations could be written to accommodate the GPU needs of a specific client app.

The complete fragment shader program is decomposed in two main parts: the OCIO shader program for the color processing and the client shader program which consumes the pixel color processing.

The OCIO shader program is fully described by the GpuShaderDesc independently from the client shader program. The only critical point is the agreement on the OCIO function shader name.

To summarize, the complete shader program is:

//                                                                    //
//               The complete fragment shader program                 //
//                                                                    //
//                                                                    //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //               The OCIO shader program                    //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //   // All global declarations                             //   //
//   //   uniform sampled3D tex3;                                //   //
//   //                                                          //   //
//   //   // All helper methods                                  //   //
//   //   vec3 computePos(vec3 color)                            //   //
//   //   {                                                      //   //
//   //      vec3 coords = color;                                //   //
//   //      ...                                                 //   //
//   //      return coords;                                      //   //
//   //   }                                                      //   //
//   //                                                          //   //
//   //   // The OCIO shader function                            //   //
//   //   vec4 OCIODisplay(in vec4 inColor)                      //   //
//   //   {                                                      //   //
//   //      vec4 outColor = inColor;                            //   //
//   //      ...                                                 //   //
//   //      outColor.rbg                                        //   //
//   //         = texture3D(tex3, computePos(inColor.rgb)).rgb;  //   //
//   //      ...                                                 //   //
//   //      return outColor;                                    //   //
//   //   }                                                      //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//                                                                    //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //             The client shader program                    //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //   uniform sampler2D image;                               //   //
//   //                                                          //   //
//   //   void main()                                            //   //
//   //   {                                                      //   //
//   //      vec4 inColor = texture2D(image, gl_TexCoord[0].st); //   //
//   //      ...                                                 //   //
//   //      vec4 outColor = OCIODisplay(inColor);               //   //
//   //      ...                                                 //   //
//   //      gl_FragColor = outColor;                            //   //
//   //   }                                                      //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//                                                                    //
////////////////////////////////////////////////////////////////////////

Usage Example: Building a GPU shader

This example is based on the code in: src/apps/ociodisplay/main.cpp

// Get the processor
//
OCIO::ConstConfigRcPtr config = OCIO::Config::CreateFromEnv();
OCIO::ConstProcessorRcPtr processor
   = config->getProcessor("ACES - ACEScg", "Output - sRGB");

// Step 1: Create a GPU shader description
//
// The three potential scenarios are:
//
//   1. Instantiate the legacy shader description.  The color processor
//      is baked down to contain at most one 3D LUT and no 1D LUTs.
//
//      This is the v1 behavior and will remain part of OCIO v2
//      for backward compatibility.
//
OCIO::GpuShaderDescRcPtr shaderDesc
      = OCIO::GpuShaderDesc::CreateLegacyShaderDesc(LUT3D_EDGE_SIZE);
//
//   2. Instantiate the generic shader description.  The color processor
//      is used as-is (i.e. without any baking step) and could contain
//      any number of 1D & 3D luts.
//
//      This is the default OCIO v2 behavior and allows a much better
//      match between the CPU and GPU renderers.
//
OCIO::GpuShaderDescRcPtr shaderDesc = OCIO::GpuShaderDesc::Create();
//
//   3. Instantiate a custom shader description.
//
//      Writing a custom shader description is a way to tailor the shaders
//      to the needs of a given client program.  This involves writing a
//      new class inheriting from the pure virtual class GpuShaderDesc.
//
//      Please refer to the GenericGpuShaderDesc class for an example.
//
OCIO::GpuShaderDescRcPtr shaderDesc = MyCustomGpuShader::Create();

shaderDesc->setLanguage(OCIO::GPU_LANGUAGE_GLSL_1_2);
shaderDesc->setFunctionName("OCIODisplay");

// Step 2: Collect the shader program information for a specific processor
//
processor->extractGpuShaderInfo(shaderDesc);

// Step 3: Create a helper to build the shader. Here we use a helper for
//         OpenGL but there will also be helpers for other languages.
//
OpenGLBuilderRcPtr oglBuilder = OpenGLBuilder::Create(shaderDesc);

// Step 4: Allocate & upload all the LUTs
//
oglBuilder->allocateAllTextures();

// Step 5: Build the complete fragment shader program using
//         g_fragShaderText which is the client shader program.
//
g_programId = oglBuilder->buildProgram(g_fragShaderText);

// Step 6: Enable the fragment shader program, and all needed textures
//
glUseProgram(g_programId);
glUniform1i(glGetUniformLocation(g_programId, "tex1"), 1);  // image texture
oglBuilder->useAllTextures(g_programId);                    // LUT textures

// Step 7: Update uniforms from dynamic property instances.
m_oglBuilder->useAllUniforms();

static CreateLegacyShaderDesc(edgeLen: int, language: PyOpenColorIO.GpuLanguage = <GpuLanguage.GPU_LANGUAGE_GLSL_1_2: 1>, functionName: str = 'OCIOMain', pixelName: str = 'outColor', resourcePrefix: str = 'ocio', uid: str = '') → PyOpenColorIO.GpuShaderDesc ¶: Create the legacy shader description.

static CreateShaderDesc(language: PyOpenColorIO.GpuLanguage = <GpuLanguage.GPU_LANGUAGE_GLSL_1_2: 1>, functionName: str = 'OCIOMain', pixelName: str = 'outColor', resourcePrefix: str = 'ocio', uid: str = '') → PyOpenColorIO.GpuShaderDesc ¶: Create the default shader description.

GpuShaderDesc(*args, **kwargs)¶: Initialize self. See help(type(self)) for accurate signature.

add3DTexture(textureName: str, samplerName: str, edgeLen: int, interpolation: PyOpenColorIO.Interpolation, values: buffer) → None¶

addTexture(textureName: str, samplerName: str, width: int, height: int, channel: PyOpenColorIO.GpuShaderCreator.TextureType, interpolation: PyOpenColorIO.Interpolation, values: buffer) → None¶

addToDeclareShaderCode(shaderCode: str) → None¶

addToFunctionFooterShaderCode(shaderCode: str) → None¶

addToFunctionHeaderShaderCode(shaderCode: str) → None¶

addToFunctionShaderCode(shaderCode: str) → None¶

addToHelperShaderCode(shaderCode: str) → None¶

begin(uid: str) → None¶: Start to collect the shader data.

clone() → PyOpenColorIO.GpuShaderCreator ¶

createShaderText(shaderDeclarations: str, shaderHelperMethods: str, shaderFunctionHeader: str, shaderFunctionBody: str, shaderFunctionFooter: str) → None¶: Create the OCIO shader program.

Note

The OCIO shader program is decomposed to allow a specific implementation to change some parts. Some product integrations add the color processing within a client shader program, imposing constraints requiring this flexibility.

end() → None¶: End to collect the shader data.

finalize() → None¶

get3DTextures() → PyOpenColorIO.GpuShaderDesc.Texture3DIterator ¶

getCacheID() → str¶

getDynamicProperties() → PyOpenColorIO.GpuShaderCreator.DynamicPropertyIterator ¶

getDynamicProperty(type: PyOpenColorIO.DynamicPropertyType) → PyOpenColorIO.DynamicProperty ¶

getFunctionName() → str¶

getLanguage() → PyOpenColorIO.GpuLanguage ¶

getNextResourceIndex() → int¶: To avoid texture/unform name clashes always append an increasing number to the resource name.

getPixelName() → str¶

getResourcePrefix() → str¶: Note

Some applications require that textures, uniforms, and helper methods be uniquely named because several processor instances could coexist.

getShaderText() → str¶: Get the complete OCIO shader program.

getTextureMaxWidth() → int¶

getTextures() → PyOpenColorIO.GpuShaderDesc.TextureIterator ¶

getUniforms() → PyOpenColorIO.GpuShaderDesc.UniformIterator ¶

getUniqueID() → str¶

hasDynamicProperty(type: PyOpenColorIO.DynamicPropertyType) → bool¶

setFunctionName(name: str) → None¶

setLanguage(language: PyOpenColorIO.GpuLanguage) → None¶: Set the shader program language.

setPixelName(name: str) → None¶: Set the pixel name variable holding the color values.

setResourcePrefix(prefix: str) → None¶: Set a prefix to the resource name.

setTextureMaxWidth(maxWidth: int) → None¶: Some graphic cards could have 1D & 2D textures with size limitations.

setUniqueID(uid: str) → None¶

class PyOpenColorIO.GpuShaderDesc.TextureType¶

Members:

TEXTURE_RED_CHANNEL

TEXTURE_RGB_CHANNEL

property name → str¶

TEXTURE_RED_CHANNEL = <TextureType.TEXTURE_RED_CHANNEL: 0>¶

TEXTURE_RGB_CHANNEL = <TextureType.TEXTURE_RGB_CHANNEL: 1>¶

class PyOpenColorIO.GpuShaderDesc.UniformData¶

getBool() → bool¶

getDouble() → float¶

getFloat3() → List[float[3]]¶

getVectorFloat() → numpy.ndarray¶

getVectorInt() → numpy.ndarray¶

property type¶

class PyOpenColorIO.GpuShaderDesc.Texture¶

property channel¶

getValues() → numpy.ndarray¶

property height¶

property interpolation¶

property samplerName¶

property textureName¶

property width¶

class PyOpenColorIO.GpuShaderDesc.Texture3D¶

property edgeLen¶

getValues() → numpy.ndarray¶

property interpolation¶

property samplerName¶

property textureName¶

class PyOpenColorIO.GpuShaderDesc.UniformIterator¶

self[arg0: int] → tuple¶

iter(self) → PyOpenColorIO.GpuShaderDesc.UniformIterator ¶

len(self) → int¶

next(self) → tuple¶

class PyOpenColorIO.GpuShaderDesc.TextureIterator¶

self[arg0: int] → PyOpenColorIO.GpuShaderDesc.Texture ¶

iter(self) → PyOpenColorIO.GpuShaderDesc.TextureIterator ¶

len(self) → int¶

next(self) → PyOpenColorIO.GpuShaderDesc.Texture ¶

class PyOpenColorIO.GpuShaderDesc.Texture3DIterator¶

self[arg0: int] → PyOpenColorIO.GpuShaderDesc.Texture3D ¶

iter(self) → PyOpenColorIO.GpuShaderDesc.Texture3DIterator ¶

len(self) → int¶

next(self) → PyOpenColorIO.GpuShaderDesc.Texture3D ¶

class PyOpenColorIO.GpuShaderDesc.DynamicPropertyIterator¶

self[arg0: int] → PyOpenColorIO.DynamicProperty ¶

iter(self) → PyOpenColorIO.GpuShaderCreator.DynamicPropertyIterator ¶

len(self) → int¶

next(self) → PyOpenColorIO.DynamicProperty ¶

class OpenColorIO_v2_1dev::GpuShaderDesc : public GpuShaderCreator ¶

This class holds the GPU-related information needed to build a shader program from a specific processor.

This class defines the interface and there are two implementations provided. The “legacy” mode implements the OCIO v1 approach of baking certain ops in order to have at most one 3D-LUT. The “generic” mode is the v2 default and allows all the ops to be processed as-is, without baking, like the CPU renderer. Custom implementations could be written to accommodate the GPU needs of a specific client app.

The complete fragment shader program is decomposed in two main parts: the OCIO shader program for the color processing and the client shader program which consumes the pixel color processing.

The OCIO shader program is fully described by the GpuShaderDesc independently from the client shader program. The only critical point is the agreement on the OCIO function shader name.

To summarize, the complete shader program is:

//                                                                    //
//               The complete fragment shader program                 //
//                                                                    //
//                                                                    //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //               The OCIO shader program                    //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //   // All global declarations                             //   //
//   //   uniform sampled3D tex3;                                //   //
//   //                                                          //   //
//   //   // All helper methods                                  //   //
//   //   vec3 computePos(vec3 color)                            //   //
//   //   {                                                      //   //
//   //      vec3 coords = color;                                //   //
//   //      ...                                                 //   //
//   //      return coords;                                      //   //
//   //   }                                                      //   //
//   //                                                          //   //
//   //   // The OCIO shader function                            //   //
//   //   vec4 OCIODisplay(in vec4 inColor)                      //   //
//   //   {                                                      //   //
//   //      vec4 outColor = inColor;                            //   //
//   //      ...                                                 //   //
//   //      outColor.rbg                                        //   //
//   //         = texture3D(tex3, computePos(inColor.rgb)).rgb;  //   //
//   //      ...                                                 //   //
//   //      return outColor;                                    //   //
//   //   }                                                      //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//                                                                    //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //             The client shader program                    //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//   //                                                          //   //
//   //   uniform sampler2D image;                               //   //
//   //                                                          //   //
//   //   void main()                                            //   //
//   //   {                                                      //   //
//   //      vec4 inColor = texture2D(image, gl_TexCoord[0].st); //   //
//   //      ...                                                 //   //
//   //      vec4 outColor = OCIODisplay(inColor);               //   //
//   //      ...                                                 //   //
//   //      gl_FragColor = outColor;                            //   //
//   //   }                                                      //   //
//   //                                                          //   //
//   //////////////////////////////////////////////////////////////   //
//                                                                    //
////////////////////////////////////////////////////////////////////////

Usage Example: Building a GPU shader

This example is based on the code in: src/apps/ociodisplay/main.cpp

// Get the processor
//
OCIO::ConstConfigRcPtr config = OCIO::Config::CreateFromEnv();
OCIO::ConstProcessorRcPtr processor
   = config->getProcessor("ACES - ACEScg", "Output - sRGB");

// Step 1: Create a GPU shader description
//
// The three potential scenarios are:
//
//   1. Instantiate the legacy shader description.  The color processor
//      is baked down to contain at most one 3D LUT and no 1D LUTs.
//
//      This is the v1 behavior and will remain part of OCIO v2
//      for backward compatibility.
//
OCIO::GpuShaderDescRcPtr shaderDesc
      = OCIO::GpuShaderDesc::CreateLegacyShaderDesc(LUT3D_EDGE_SIZE);
//
//   2. Instantiate the generic shader description.  The color processor
//      is used as-is (i.e. without any baking step) and could contain
//      any number of 1D & 3D luts.
//
//      This is the default OCIO v2 behavior and allows a much better
//      match between the CPU and GPU renderers.
//
OCIO::GpuShaderDescRcPtr shaderDesc = OCIO::GpuShaderDesc::Create();
//
//   3. Instantiate a custom shader description.
//
//      Writing a custom shader description is a way to tailor the shaders
//      to the needs of a given client program.  This involves writing a
//      new class inheriting from the pure virtual class GpuShaderDesc.
//
//      Please refer to the GenericGpuShaderDesc class for an example.
//
OCIO::GpuShaderDescRcPtr shaderDesc = MyCustomGpuShader::Create();

shaderDesc->setLanguage(OCIO::GPU_LANGUAGE_GLSL_1_2);
shaderDesc->setFunctionName("OCIODisplay");

// Step 2: Collect the shader program information for a specific processor
//
processor->extractGpuShaderInfo(shaderDesc);

// Step 3: Create a helper to build the shader. Here we use a helper for
//         OpenGL but there will also be helpers for other languages.
//
OpenGLBuilderRcPtr oglBuilder = OpenGLBuilder::Create(shaderDesc);

// Step 4: Allocate & upload all the LUTs
//
oglBuilder->allocateAllTextures();

// Step 5: Build the complete fragment shader program using
//         g_fragShaderText which is the client shader program.
//
g_programId = oglBuilder->buildProgram(g_fragShaderText);

// Step 6: Enable the fragment shader program, and all needed textures
//
glUseProgram(g_programId);
glUniform1i(glGetUniformLocation(g_programId, "tex1"), 1);  // image texture
oglBuilder->useAllTextures(g_programId);                    // LUT textures

// Step 7: Update uniforms from dynamic property instances.
m_oglBuilder->useAllUniforms();

Public Functions

virtual GpuShaderCreatorRcPtr clone() const override¶

virtual unsigned getNumUniforms() const noexcept = 0¶

virtual const char *getUniform(unsigned index, UniformData &data) const = 0¶: Returns name of uniform and data as parameter.

virtual unsigned getNumTextures() const noexcept = 0¶

virtual void getTexture(unsigned index, const char *&textureName, const char *&samplerName, unsigned &width, unsigned &height, TextureType &channel, Interpolation &interpolation) const = 0¶

virtual void getTextureValues(unsigned index, const float *&values) const = 0¶

virtual unsigned getNum3DTextures() const noexcept = 0¶

virtual void get3DTexture(unsigned index, const char *&textureName, const char *&samplerName, unsigned &edgelen, Interpolation &interpolation) const = 0¶

virtual void get3DTextureValues(unsigned index, const float *&values) const = 0¶

const char *getShaderText() const noexcept¶: Get the complete OCIO shader program.

GpuShaderDesc(const GpuShaderDesc&) = delete¶

GpuShaderDesc &operator=(const GpuShaderDesc&) = delete¶

virtual ~GpuShaderDesc()¶: Do not use (needed only for pybind11).

Public Static Functions

static GpuShaderDescRcPtr CreateLegacyShaderDesc(unsigned edgelen)¶: Create the legacy GPU shader description. This is now deprecated (to be removed in the coming release i.e. 2.1.x). Do not use it because that’s broken. So, this method has been replaced by the pair Processor::getOptimizedLegacyGPUProcessor() and GpuShaderDesc::CreateShaderDesc().

static GpuShaderDescRcPtr CreateShaderDesc()¶: Create the default shader description.

struct UniformData¶

Used to retrieve uniform information. UniformData m_type indicates the type of uniform and what member of the structure should be used:

UNIFORM_DOUBLE: m_getDouble.
UNIFORM_BOOL: m_getBool.
UNIFORM_FLOAT3: m_getFloat3.
UNIFORM_VECTOR_FLOAT: m_vectorFloat.
UNIFORM_VECTOR_INT: m_vectorInt.

Public Functions

UniformData() = default¶

UniformData(const UniformData &data) = default¶

Public Members

UniformDataType m_type = {UNIFORM_UNKNOWN}¶

DoubleGetter m_getDouble = {}¶

BoolGetter m_getBool = {}¶

Float3Getter m_getFloat3 = {}¶

struct OpenColorIO_v2_1dev::GpuShaderDesc::UniformData::VectorFloat m_vectorFloat¶

struct OpenColorIO_v2_1dev::GpuShaderDesc::UniformData::VectorInt m_vectorInt¶

struct VectorFloat¶

Public Members

SizeGetter m_getSize = {}¶

VectorFloatGetter m_getVector = {}¶

struct VectorInt¶

Public Members

SizeGetter m_getSize = {}¶

VectorIntGetter m_getVector = {}¶

typedef std::shared_ptr<const GpuShaderDesc> OpenColorIO_v2_1dev::ConstGpuShaderDescRcPtr¶

typedef std::shared_ptr<GpuShaderDesc> OpenColorIO_v2_1dev::GpuShaderDescRcPtr¶