OpenGL Shading Backward Compatibility Language

Question

I noticed that my GLSL shaders do not compile when the GLSL version is below 130.

What are the most important elements for having a backward compatible shader source? I don’t want to have full backward compatibility, but I would like to understand the basic recommendations for creating simple (cross-compatible) shaders running on a GPU with GLSL below 130.

Of course, the problem can be solved using a preprocessor.

#if __VERSION__ < 130
#define VERTEX_IN attribute
#else
#define VERTER_IN in
#endif

But there are probably a lot of problems that I ignore.

Answer 1

, , . , , , .

, GL_ARB_shading_language_include ( , ) , include source:

//  Copyright (C) 2011-2013 Luca Piccioni
// 
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
// 
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
// 
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

// @BeginInterface

// Shader renderer

// Symbol defined if running on NVIDIA renderer.
#define DS_VENDOR_NVIDIA            1
// Symbol defined if running on ATI/AMD renderer.
#define DS_VENDOR_AMD               2
// Symbol defined if running on INTEL renderer
#define DS_VENDOR_INTEL             3

// Shader inputs and outputs keywords
//
// - ATTRIBUTE: used to mark a vertex shader inputs
// - SHADER_IN: used to mark a non-vertex shader inputs
// - SHADER_OUT: used to mark a non-fragment shader output
// - OUT: used to mark a fragment shader output
#if __VERSION__ >= 130

#define ATTRIBUTE in
#define SHADER_IN in
#define SHADER_OUT out
#define OUT out

#else

#define ATTRIBUTE attribute
#define SHADER_IN varying
#define SHADER_OUT varying
#define OUT

#endif

// Support array attributes
#if __VERSION__ >= 130

#define ARRAY_ATTRIBUTE(name, size) name[size]

#else

#define ARRAY_ATTRIBUTE(name, size) name[size]

#endif

// Uniform blocks
#if __VERSION__ >= 130

#define BEGIN_UNIFORM_BLOCK(name)   uniform name {

#define END_UNIFORM_BLOCK() };

#else

#define BEGIN_UNIFORM_BLOCK(name)

#define END_UNIFORM_BLOCK()

#endif

// Input and output blocks
#if __VERSION__ >= 150

#define BEGIN_INPUT_BLOCK(name) in name {
#define END_INPUT_BLOCK() };

#define BEGIN_OUTPUT_BLOCK(name) out name {
#define END_OUTPUT_BLOCK() };

#else

#define BEGIN_INPUT_BLOCK(name)
#define END_INPUT_BLOCK()

#define BEGIN_OUTPUT_BLOCK(name)
#define END_OUTPUT_BLOCK()

#endif

// Texturing functions
#if __VERSION__ >= 130

#define TEXTURE_2D texture
#define TEXTURE_3D texture
#define TEXTURE_RECT texture
#define TEXTURE_CUBE texture

#if __VERSION__ >= 150
#define TEXTURE_SIZE(sampler) textureSize(sampler)
#else
#define TEXTURE_SIZE(sampler) sampler ## _Size
#endif

#else

#define TEXTURE_2D texture2D
#define TEXTURE_3D texture3D
#define TEXTURE_RECT texture2DRect
#define TEXTURE_CUBE textureCube

#endif

// Invariance
#if __VERSION__ >= 120
#define INVARIANT invariant
#else
#define INVARIANT
#endif

// Attribute location
#if defined(GL_ARB_explicit_attrib_location)
#define LOCATION(loc)       layout(location = loc)
#else
#define LOCATION(loc)
#endif

// Geometry shader layout
#if __VERSION__ >= 150
#define GEOMETRY_LAYOUT_IN(from) layout (from) in
#define GEOMETRY_LAYOUT(to, max) layout (to, max_vertices = max) out
#else
#define GEOMETRY_LAYOUT_IN(from)
#define GEOMETRY_LAYOUT(to, max)
#endif

// @EndInterface

, , . , , ( , > 1.0 ).

, . GLSL 1.50 , .

Answer 2

• #version 110 #version 120
• ShaderAnalyst ATI
• .

Answer 3

"OpenGL Shading Language, Bill Licea-Kane, AMD, SIGGRAPH 2009" . , , GLSL-140, 130 120:

#version 150 compatibility

Answer 4

remove the #version line from your shaders and test your code on different computers with different GPU capabilities. You will see that your compatibility with the shader will increase. The #version directive can sometimes cause a shader to fail, even if the GPU on this computer can execute all the shader code if it does not have a version number.