Class TGLSLProgram

Unit

Declaration

type TGLSLProgram = class(TObject)

Description

Easily handle program in GLSL (OpenGL Shading Language).

Hierarchy

  • TObject
  • TGLSLProgram

Overview

Methods

Public constructor Create;
Public destructor Destroy; override;
Public procedure AttachVertexShader(const S: string);
Public procedure AttachGeometryShader(const S: string);
Public procedure AttachFragmentShader(const S: string);
Public procedure AttachShader(const ShaderType: TShaderType; const S: string); overload;
Public procedure AttachShader(const ShaderType: TShaderType; const Parts: TStrings); overload;
Public procedure DetachAllShaders;
Public procedure Link; overload; virtual;
Public procedure Link(Ignored: boolean); overload; deprecated 'use parameterless Link method';
Public procedure Enable;
Public class procedure Disable;
Public function SetupUniforms(var BoundTextureUnits: Cardinal): boolean; virtual;
Public function DebugInfo: string;
Public function ProgramInfoLog: string;
Public function RunningInHardware: boolean;
Public class function ClassSupport: TGLSupport; deprecated 'use GLFeatures.Shaders';
Public function Uniform(const Name: string): TGLSLUniform; overload;
Public function Uniform(const Name: string; const AUniformNotFoundAction: TUniformNotFoundAction): TGLSLUniform; overload;
Public procedure SetUniform(const Name: string; const Value: boolean ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TGLint ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector2Integer; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector3Integer; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector4Integer; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TGLfloat ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector2 ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector3 ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector4 ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TMatrix2 ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TMatrix3 ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TMatrix4 ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TBooleanList ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TLongIntList ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TSingleList ; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector2List; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector3List; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TVector4List; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TMatrix3List; const ForceException: boolean = false); overload;
Public procedure SetUniform(const Name: string; const Value: TMatrix4List; const ForceException: boolean = false); overload;
Public function Attribute(const Name: string): TGLSLAttribute;
Public function AttributeOptional(const Name: string): TGLSLAttribute;
Public function VertexAttribPointer(const Name: string; LocationOffset: TGLSLAttribute.TLocationOffset; Size: TGLint; AType: TGLenum; Normalized: TGLboolean; Stride: TGLsizei; Ptr: Pointer): TGLint; deprecated 'use TGLSLAttribute.EnableArray';
Public class procedure DisableVertexAttribArray(Location: TGLint); deprecated 'use TGLSLAttribute.DisableArray';
Public procedure SetAttribute(const Name: string; const Value: TGLfloat); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TVector2); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TVector3); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TVector4); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TMatrix3); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TMatrix4); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TVector4Integer); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TVector4Byte); overload; deprecated 'use TGLSLAttribute.SetValue';
Public procedure SetAttribute(const Name: string; const Value: TGLdouble); overload; deprecated 'use TGLSLAttribute.SetValue';

Properties

Public property Support: TGLSupport read FSupport; deprecated 'use GLFeatures.Shaders';
Public property UniformNotFoundAction: TUniformNotFoundAction read FUniformNotFoundAction write FUniformNotFoundAction default uaException;
Public property UniformTypeMismatchAction: TUniformTypeMismatchAction read FUniformTypeMismatchAction write FUniformTypeMismatchAction default utGLError; deprecated 'do not use this, it is ignored (old implementation was prohibitively slow)';
Public class property Current: TGLSLProgram read GetCurrent write SetCurrent; deprecated 'use RenderContext.CurrentProgram';

Description

Methods

Public constructor Create;
 
Public destructor Destroy; override;
 
Public procedure AttachVertexShader(const S: string);

Create shader from given string, compile it and attach to current program.

For desktop OpenGL, you can attach more than one shader of given type, just make sure that only one main() function is among each type (otherwise link error will be raised later). For OpenGLES, this is not allowed, so don't use this if you want to work with OpenGLES too.

If you want to explicitly get rid of old shaders, use DetachAllShaders.

Exceptions raised
EGLSLShaderCompileError
If the shader source code cannot be compiled, exception message contains precise description from OpenGL where the error is.
Public procedure AttachGeometryShader(const S: string);
 
Public procedure AttachFragmentShader(const S: string);
 
Public procedure AttachShader(const ShaderType: TShaderType; const S: string); overload;
 
Public procedure AttachShader(const ShaderType: TShaderType; const Parts: TStrings); overload;

Attach multiple shader parts for given type.

For normal OpenGL, we can use GLSL separate compilation units. So this is equivalent to just calling AttachShader(ShaderType, Parts[I]) for each part.

For OpenGL ES, this is unfortunately not possible, you can only attach a single shader of a given type (see http://www.khronos.org/opengles/sdk/docs/man/xhtml/glAttachShader.xml ). So we simply concatenate the shaders into one.

Public procedure DetachAllShaders;
 
Public procedure Link; overload; virtual;

Link the program, this should be done after attaching all shaders and before actually using the program.

Exceptions raised
EGLSLProgramLinkError
If the program cannot be linked, exception message contains precise description from OpenGL where the error is.
Public procedure Link(Ignored: boolean); overload; deprecated 'use parameterless Link method';

Warning: this symbol is deprecated: use parameterless Link method

 
Public procedure Enable;

Enable (use) this program. Shortcut for RenderContext.CurrentProgram := Self.

Public class procedure Disable;

Disable this program (use the fixed function pipeline). Shortcut for RenderContext.CurrentProgram := nil.

Public function SetupUniforms(var BoundTextureUnits: Cardinal): boolean; virtual;

Override this to set uniform values, in particular to bind the textures used by this shader, right after each Enable call.

This is automatically called after every Enable by VRML renderer (when it renders shapes) or scene manager (when it renders screen effects). If you use this TGLSLProgram directly (if you call Enable yourself), then it's your responsibility to call this method explicitly, if you want shaders using it to work.

You can set any uniform values, and generally do anything you want to be done each time this shader is enabled. In particular, you can bind textures and set corresponding uniform variables of them. Increase BoundTextureUnits appropriately.

Returns False is some texture couldn't be bound.

Public function DebugInfo: string;

Returns multiline debug info about current program. Things like how it's supported (not at all ? ARB extension ? standard ?), names of active uniform and attribute variables etc.

fglrx (Radeon closed-source OpenGL drivers) are buggy (that's not news, I know...) and they report GL_INVALID_ENUM on some queries here. We detect this, and still produce nice debug message, without raising any exception (after all, we have to workaround fglrx bugs, and try to run our program anyway...). What's important for caller is that we have to check first whether there are any OpenGL errors pending, and raise exceptions on them.

Exceptions raised
EOpenGLError
If any OpenGL error will be detected.
Public function ProgramInfoLog: string;

This is program info log, given to you from OpenGL after the program is linked.

Public function RunningInHardware: boolean;

After the program is linked, you can check this.

Note that this is necessarily implemented in quite hacky way (by looking at ProgramInfoLog), there is no way currently (AFAIK ?) to get this information cleanly from OpenGL. In case of doubts, we try to "trust" OpenGL to execute shader in hardware. Return False only when we see clear indication in ProgramInfoLog that it'll run in software.

Public class function ClassSupport: TGLSupport; deprecated 'use GLFeatures.Shaders';

Warning: this symbol is deprecated: use GLFeatures.Shaders

What support do we get from current OpenGL context ?

This is much like Support, but it's a class function.

Public function Uniform(const Name: string): TGLSLUniform; overload;

Get the uniform instance. It can be used to make repeated TGLSLUniform.SetValue calls. You must link the program first.

If the uniform doesn't exist (or is unused), the action we take depends on UniformNotFoundAction property (by default – uaException). The overloaded version with extra AUniformNotFoundAction parameter follows this parameter value.

Exceptions raised
EGLSLUniformNotFound
If the variable is not found within the program and we the behaviour (determined by AUniformTypeMismatchAction parameter or UniformTypeMismatchAction property) is uaException.
Public function Uniform(const Name: string; const AUniformNotFoundAction: TUniformNotFoundAction): TGLSLUniform; overload;
 
Public procedure SetUniform(const Name: string; const Value: boolean ; const ForceException: boolean = false); overload;

Set appropriate uniform variable value. The used type must match the type of this variable in GLSL program.

OpenGL forces some constraints on using this:

  • This should be used only after linking, and re-linking clears (sets to zero) all uniform variables values.

  • This GLSL program must be currently enabled for this to work. So calling this automatically calls Enable and sets RenderContext.CurrentProgram.

    This is required by OpenGL glUniform* commands. glGetUniformLocation take program id as parameter, so they can operate on any program. But glUniform* operate only on active program.

  • Only active uniforms variables may be set. Active means, quoting OpenGL manpages, a variable that is determined during the link operation that it may be accessed during program execution. In other words, when linking GLSL program, unused variables may be eliminated, and you cannot set them by SetUniform.

    Call DebugInfo to see what uniform variables are considered active for your shader.

    You can change UniformNotFoundAction not to silently ignore setting of inactive (or not existing) uniform values.

Exceptions raised
EGLSLUniformNotFound
If the variable is not found within the program and UniformNotFoundAction = uaException (default) or ForceException.
EGLSLUniformTypeMismatch
If the variable type doesn't match the type declared in shader code. Raised only if UniformTypeMismatchAction = utException or ForceException.

Note that both EGLSLUniformNotFound and EGLSLUniformTypeMismatch may be comfortably catched by an umbrella class EGLSLUniformInvalid.

Public procedure SetUniform(const Name: string; const Value: TGLint ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector2Integer; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector3Integer; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector4Integer; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TGLfloat ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector2 ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector3 ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector4 ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TMatrix2 ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TMatrix3 ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TMatrix4 ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TBooleanList ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TLongIntList ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TSingleList ; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector2List; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector3List; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TVector4List; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TMatrix3List; const ForceException: boolean = false); overload;
 
Public procedure SetUniform(const Name: string; const Value: TMatrix4List; const ForceException: boolean = false); overload;
 
Public function Attribute(const Name: string): TGLSLAttribute;

Get the attribute instance. It can be used to make repeated TGLSLAttribute.SetValue and TGLSLAttribute.EnableArray.

Exceptions raised
EGLSLAttributeNotFound
If the variable is not found within the program.

Note that this is only one of the many things that can go wrong. And on most cases we don't raise any error, instead OpenGL sets it's error state and you probably want to call CheckGLErrors from time to time to catch them.

Public function AttributeOptional(const Name: string): TGLSLAttribute;

Get the attribute instance. It can be used to make repeated TGLSLAttribute.SetValue and TGLSLAttribute.EnableArray.

Returned attribute has TGLSLAttribute.Location equal to -1. All the calls to TGLSLAttribute.SetValue or TGLSLAttribute.EnableArray or TGLSLAttribute.DisableArray methods are silently ignored.

Public function VertexAttribPointer(const Name: string; LocationOffset: TGLSLAttribute.TLocationOffset; Size: TGLint; AType: TGLenum; Normalized: TGLboolean; Stride: TGLsizei; Ptr: Pointer): TGLint; deprecated 'use TGLSLAttribute.EnableArray';

Warning: this symbol is deprecated: use TGLSLAttribute.EnableArray

Load and enable vertex attribute data. This calls glVertexAttribPointer and enables it by glEnableVertexAttribArray (or ARB extension equivalents), see OpenGL reference for details.

The attribute name is automatically resolved to a "location". We add LocationOffset (useful if you want to load matrix attributes, when you have to load matrix columns separately, with LocationOffset = column index).

For repeated usage, it's better to use Attribute method, and repeatedly call TGLSLAttribute.EnableArray on the same TGLSLAttribute instance.

Returns

Attribute location (with LocationOffset already applied). You can use it with DisableVertexAttribArray.

Exceptions raised
EGLSLAttributeNotFound
If the variable is not found within the program.
Public class procedure DisableVertexAttribArray(Location: TGLint); deprecated 'use TGLSLAttribute.DisableArray';

Warning: this symbol is deprecated: use TGLSLAttribute.DisableArray

 
Public procedure SetAttribute(const Name: string; const Value: TGLfloat); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

Set attribute variable value. The used type must match the type of this variable in GLSL program.

OpenGL forces some constraints on using this, see SetUniform. In short: use this only after linking the program. The program is automatically enabled (set as RenderContext.CurrentProgram) by this. And note that attributes declared but not actually used in shader code may be eliminated, use DebugInfo to see which attributes are actually used (active in OpenGL terminology).

These should not be often used. Usually, you should rather load attribute arrays, by VertexAttribPointer. You should also get attribute by the Attribute method, as TGLSLAttribute, and then call TGLSLAttribute.SetValue or TGLSLAttribute.EnableArray.

Exceptions raised
EGLSLAttributeNotFound
If the variable is not found within the program.

Note that this is only one of the many things that can go wrong. And on most cases we don't raise any error, instead OpenGL sets it's error state and you probably want to call CheckGLErrors from time to time to catch them.

Public procedure SetAttribute(const Name: string; const Value: TVector2); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 
Public procedure SetAttribute(const Name: string; const Value: TVector3); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 
Public procedure SetAttribute(const Name: string; const Value: TVector4); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 
Public procedure SetAttribute(const Name: string; const Value: TMatrix3); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 
Public procedure SetAttribute(const Name: string; const Value: TMatrix4); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 
Public procedure SetAttribute(const Name: string; const Value: TVector4Integer); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 
Public procedure SetAttribute(const Name: string; const Value: TVector4Byte); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 
Public procedure SetAttribute(const Name: string; const Value: TGLdouble); overload; deprecated 'use TGLSLAttribute.SetValue';

Warning: this symbol is deprecated: use TGLSLAttribute.SetValue

 

Properties

Public property Support: TGLSupport read FSupport; deprecated 'use GLFeatures.Shaders';

Warning: this symbol is deprecated: use GLFeatures.Shaders

 
Public property UniformNotFoundAction: TUniformNotFoundAction read FUniformNotFoundAction write FUniformNotFoundAction default uaException;

What to do when GLSL uniform variable is accessed (by SetUniform or Uniform) but doesn't exist in the shader. Note that OpenGL aggresively removes unused code and variables from the shader when compiling/linking, so this also happens for "declared but unused" variables.

This is only the default value, each Uniform method call may explicitly use other TUniformNotFoundAction.

See also
TUniformNotFoundAction
What to do when GLSL uniform variable is set (TGLSLProgram.SetUniform) but doesn't exist in the shader.
Public property UniformTypeMismatchAction: TUniformTypeMismatchAction read FUniformTypeMismatchAction write FUniformTypeMismatchAction default utGLError; deprecated 'do not use this, it is ignored (old implementation was prohibitively slow)';

Warning: this symbol is deprecated: do not use this, it is ignored (old implementation was prohibitively slow)

What to do when GLSL uniform variable is set (by TGLSLUniform.SetValue or SetUniform) but is declared with an incompatible type in the shader source.

Note that the default (utGLError) is fastest. Other options will need to check OpenGL error state often, which may cause performance drop.

See also
TUniformTypeMismatchAction
What to do when GLSL uniform variable is set (by TGLSLProgram.SetUniform) to the type that doesn't match type declared in GLSL shader.
Public class property Current: TGLSLProgram read GetCurrent write SetCurrent; deprecated 'use RenderContext.CurrentProgram';

Warning: this symbol is deprecated: use RenderContext.CurrentProgram

Currently enabled GLSL program. Nil if fixed-function pipeline should be used. Setting this property encapsulates the OpenGL glUseProgram (or equivalent ARB extension), additionally preventing redundant glUseProgram calls.


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