Introduction

Unit CastleGLShaders

Description
Uses
Classes, Interfaces, Objects and Records
Functions and Procedures
Types
Constants
Variables

Description

OpenGL shaders in GLSL language.

  • Creating/destroying the TGLSLProgram instance immediately creates/destroys appropriate program on GPU. So be sure to create/destroy it only when you have OpenGL context available (for example, create in TCastleWindowBase.OnOpen and destroy in TCastleWindowBase.OnClose).

  • Upon creation, we check current OpenGL context abilities. Currently three support levels are possible: no support at all (old OpenGL), support through ARB extensions, or support built-in (newer OpenGL versions, >= 2.0).

    All three cases are automatically handled inside, so usually you do not have to care about these details. Note that "none" support (on older OpenGL version with no appropriate ARB extensions) means that shaders are not really initialized at all.

Uses

Overview

Classes, Interfaces, Objects and Records

Name Description
Class EGLSLError Common class for exceptions related to GLSL programs.
Class EGLSLShaderCompileError  
Class EGLSLProgramLinkError  
Class EGLSLAttributeNotFound  
Class EGLSLTransformFeedbackError  
Class EGLSLUniformInvalid  
Class EGLSLUniformNotFound  
Class EGLSLUniformTypeMismatch  
Record TGLSLUniform  
Record TGLSLAttribute  
Class TGLSLProgram Easily handle program in GLSL (OpenGL Shading Language).

Functions and Procedures

function GetCurrentProgram: TGLSLProgram; deprecated 'use RenderContext.CurrentProgram';
procedure SetCurrentProgram(const Value: TGLSLProgram); deprecated 'use RenderContext.CurrentProgram';

Types

TGLuintList = TCardinalList;
TUniformNotFoundAction = (...);
TUniformTypeMismatchAction = (...);
TGLSLAttributeList = specialize TList<TGLSLAttribute>;
TLocationCache = specialize TDictionary<String, TGLint>;
TGLSLProgramList = specialize TObjectList<TGLSLProgram>;

Variables

LogShaders: boolean;
property CurrentProgram: TGLSLProgram read GetCurrentProgram write SetCurrentProgram;

Description

Functions and Procedures

function GetCurrentProgram: TGLSLProgram; deprecated 'use RenderContext.CurrentProgram';

Warning: this symbol is deprecated: use RenderContext.CurrentProgram

 
procedure SetCurrentProgram(const Value: TGLSLProgram); deprecated 'use RenderContext.CurrentProgram';

Warning: this symbol is deprecated: use RenderContext.CurrentProgram

 

Types

TGLuintList = TCardinalList;
 
TUniformNotFoundAction = (...);

What to do when GLSL uniform variable is set (TGLSLProgram.SetUniform) but doesn't exist in the shader.

Values
  • uaWarning: Report that uniform variable not found to WritelnWarning.
  • uaException: Report that uniform variable not found by raising EGLSLUniformNotFound.
  • uaIgnore: Ignore the fact that uniform variable doesn't exist in the GLSL shader. Do not warn anywhere.
TUniformTypeMismatchAction = (...);

Warning: this symbol is deprecated.

What to do when GLSL uniform variable is set (by TGLSLProgram.SetUniform) to the type that doesn't match type declared in GLSL shader.

Do not use this. It has no effect anymore. Checking the GLSL uniform types requires doing glGetError after every uniform set, which is prohibitively slow. One day we may implement a better way to do this (using the info we get about uniforms in TGLSLProgram.DebugInfo) and then this will be useful again.

Values
  • utGLError: Do not catch uniform type mismatch, leaving it to OpenGL. This will cause OpenGL error "invalid operation" (possibly resulting in an exception in some later code that checks OpenGL errors).

    This is unsafe (you may get OpenGL errors later), but is also fastest. Other options have to detect invalid types, which means checking the OpenGL error state each time you set uniform value.

  • utWarning: Report type mismatch to WritelnWarning.
  • utException: Report type mismatch by raising EGLSLUniformTypeMismatch.
TGLSLAttributeList = specialize TList<TGLSLAttribute>;
 
TLocationCache = specialize TDictionary<String, TGLint>;
 
TGLSLProgramList = specialize TObjectList<TGLSLProgram>;
 

Variables

LogShaders: boolean;
 
property CurrentProgram: TGLSLProgram read GetCurrentProgram write SetCurrentProgram;

Warning: this symbol is deprecated.

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.

Use RenderContext.CurrentProgram

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Copyright Michalis Kamburelis and other Castle Game Engine developers.
Thank you to Paweł Wojciechowicz from Cat-astrophe Games for various graphics.
This documentation is also open-source and you can even redistribute it on open-source terms.

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