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doc: compiling Portability page code snippets.

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Vladimír Vondruš 8 years ago
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4 changed files with 127 additions and 55 deletions
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  1. 63
      doc/portability.dox
  2. 18
      doc/snippets/CMakeLists.txt
  3. 53
      doc/snippets/Magnum.cpp
  4. 48
      doc/snippets/MagnumPlatform-portability.cpp

63
doc/portability.dox
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@ -48,14 +48,7 @@ If you include @ref Magnum.h, you get these predefined macros:
Example usage:
@code{.cpp}
#ifndef MAGNUM_TARGET_GLES
Renderer::setPolygonMode(Renderer::PolygonMode::Lines);
// draw mesh as wireframe...
#else
// use different mesh, as polygon mode is not supported in OpenGL ES...
#endif
@endcode
@snippet Magnum.cpp portability-targets
Each feature is marked accordingly if it is not available in some targets. See
also @ref requires-gl, @ref requires-gles20 and @ref requires-gles30.
@ -85,15 +78,7 @@ thus the decision cannot be made at compile time. Header @ref Extensions.h
contains list of extensions, which you can pass to
@ref Context::isExtensionSupported() and decide based on that:
@code{.cpp}
if(Context::current().isExtensionSupported<GL::ARB::geometry_shader4>()) {
// draw mesh with wireframe on top in one pass using geometry shader...
} else {
// draw underlying mesh...
Renderer::setPolygonMode(Renderer::PolygonMode::Lines);
// draw mesh as wirefreame in second pass...
}
@endcode
@snippet Magnum.cpp portability-extensions
You can also decide on particular OpenGL version using @ref Context::isVersionSupported(),
but remember that some features from that version might be available even if
@ -104,10 +89,7 @@ extensions, you can use macros @ref MAGNUM_ASSERT_EXTENSION_SUPPORTED() or
@ref MAGNUM_ASSERT_VERSION_SUPPORTED() to add mandatory requirement of given
extension or version:
@code{.cpp}
MAGNUM_ASSERT_EXTENSION_SUPPORTED(GL::ARB::geometry_shader4);
// just use geometry shader and don't care about old hardware
@endcode
@snippet Magnum.cpp portability-extension-assert
Each class, function or enum value is marked accordingly if it needs specific
extension or specific OpenGL version. Various classes in Magnum are taking
@ -130,13 +112,9 @@ you can decide on the syntax in your shader code. You can also use
@ref Context::supportedVersion() to conveniently select the first supported
version from a list:
@code{.cpp}
// MyShader.cpp
Version version = Context::current().supportedVersion({Version::GL430,
Version::GL330,
Version::GL210});
attachShader(Shader::fromFile(version, "MyShader.vert"));
@endcode
<p>
@snippet Magnum.cpp portability-shaders
</p>
@code{.vert}
// MyShader.vert
@ -161,12 +139,7 @@ be available in given GLSL version (e.g. causing compilation errors). You can
use @ref Context::isExtensionSupported(Version) const to check that the
extension is present in given version:
@code{.cpp}
if(!Context::current().isExtensionSupported<Extensions::GL::ARB::explicit_attrib_location>(version)) {
bindAttributeLocation(Position::Location, "position");
// ...
}
@endcode
@snippet Magnum.cpp portability-shaders-bind
See also @ref AbstractShaderProgram class documentation for information about
specifying attribute location, uniform location and texture binding unit in
@ -198,27 +171,7 @@ and desktop (using SDL2 toolkit). Thanks to static polymorphism most of the
functions will work on both without changes, the main difference might (or
might not, depending what you use) be in particular event handlers:
@code{.cpp}
#ifndef MAGNUM_TARGET_GLES
#include <Platform/Sdl2Application.h>
#else
#include <Platform/XEglApplication.h>
#endif
class MyApplication: public Platform::Application {
public:
MyApplication(const Arguments& arguments);
protected:
void viewportEvent(const Vector2i& size) override;
void drawEvent() override;
void keyPressEvent(KeyEvent& event) override;
};
// ...
MAGNUM_APPLICATION_MAIN(MyApplication)
@endcode
@snippet MagnumPlatform-portability.cpp application
And corresponding CMake code. Note that we need to call @cmake find_package() @ce
twice, first to get the @ref MAGNUM_TARGET_GLES variable and then again to find

18
doc/snippets/CMakeLists.txt
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@ -93,6 +93,24 @@ if(WITH_SDL2APPLICATION)
endif()
endif()
if((NOT TARGET_GLES AND WITH_SDL2APPLICATION) OR (TARGET_GLES AND WITH_XEGLAPPLICATION))
add_library(snippets-MagnumPlatform-portability STATIC MagnumPlatform-portability.cpp)
if(TARGET_GLES)
target_link_libraries(snippets-MagnumPlatform-portability PRIVATE MagnumXEglApplication)
else()
target_link_libraries(snippets-MagnumPlatform-portability PRIVATE MagnumSdl2Application)
endif()
set_target_properties(
snippets-MagnumPlatform-portability
PROPERTIES FOLDER "Magnum/doc/snippets")
# Otherwise it's not linked correctly. I have no idea why, but whatever.
if(CMAKE_VERSION VERSION_LESS 3.0)
find_package(SDL2 REQUIRED)
target_link_libraries(snippets-MagnumPlatform-portability PRIVATE SDL2::SDL2)
endif()
endif()
if(WITH_WINDOWLESSEGLAPPLICATION)
add_library(snippets-MagnumPlatform-custom STATIC MagnumPlatform-custom.cpp)
add_library(snippets-MagnumPlatform-windowless STATIC MagnumPlatform-windowless.cpp)

53
doc/snippets/Magnum.cpp
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@ -207,6 +207,49 @@ texture.setStorage(4, TextureFormat::RGBA8, {256, 256});
}
#endif
{
/* [portability-targets] */
#ifndef MAGNUM_TARGET_GLES
Renderer::setPolygonMode(Renderer::PolygonMode::Line);
// draw mesh as wireframe...
#else
// use different mesh, as polygon mode is not supported in OpenGL ES...
#endif
/* [portability-targets] */
}
#ifndef MAGNUM_TARGET_GLES
{
/* [portability-extensions] */
if(Context::current().isExtensionSupported<Extensions::GL::ARB::geometry_shader4>()) {
// draw mesh with wireframe on top in one pass using geometry shader...
} else {
// draw underlying mesh...
Renderer::setPolygonMode(Renderer::PolygonMode::Line);
// draw mesh as wirefreame in second pass...
}
/* [portability-extensions] */
}
{
/* [portability-extension-assert] */
MAGNUM_ASSERT_EXTENSION_SUPPORTED(Extensions::GL::ARB::geometry_shader4);
// just use geometry shader and don't care about old hardware
/* [portability-extension-assert] */
}
{
/* [portability-shaders] */
// MyShader.cpp
Version version = Context::current().supportedVersion({Version::GL430,
Version::GL330,
Version::GL210});
Shader vert{version, Shader::Type::Vertex};
vert.addFile("MyShader.vert");
/* [portability-shaders] */
}
#endif
#ifndef MAGNUM_TARGET_GLES
struct MyShader: AbstractShaderProgram {
/* [AbstractShaderProgram-input-attributes] */
@ -282,6 +325,16 @@ MyShader& setTransformFeedback(TransformFeedback& feedback, Int totalCount, Buff
/* [AbstractShaderProgram-xfb] */
void foo() {
{
Version version{};
/* [portability-shaders-bind] */
if(!Context::current().isExtensionSupported<Extensions::GL::ARB::explicit_attrib_location>(version)) {
bindAttributeLocation(Position::Location, "position");
// ...
}
/* [portability-shaders-bind] */
}
/* [AbstractShaderProgram-binding] */
// Shaders attached...

48
doc/snippets/MagnumPlatform-portability.cpp
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@ -0,0 +1,48 @@
/*
This file is part of Magnum.
Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
Vladimír Vondruš <mosra@centrum.cz>
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/
/* [application] */
#ifndef MAGNUM_TARGET_GLES
#include <Magnum/Platform/Sdl2Application.h>
#else
#include <Magnum/Platform/XEglApplication.h>
#endif
using namespace Magnum;
class MyApplication: public Platform::Application {
public:
MyApplication(const Arguments& arguments);
protected:
void viewportEvent(const Vector2i& size) override;
void drawEvent() override;
void keyPressEvent(KeyEvent& event) override;
};
// ...
MAGNUM_APPLICATION_MAIN(MyApplication)
/* [application] */
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