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106 lines
3.7 KiB
106 lines
3.7 KiB
#ifndef Magnum_MeshTools_FullScreenTriangle_h |
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#define Magnum_MeshTools_FullScreenTriangle_h |
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/* |
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This file is part of Magnum. |
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Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, |
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2020 Vladimír Vondruš <mosra@centrum.cz> |
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Permission is hereby granted, free of charge, to any person obtaining a |
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copy of this software and associated documentation files (the "Software"), |
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to deal in the Software without restriction, including without limitation |
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the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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and/or sell copies of the Software, and to permit persons to whom the |
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Software is furnished to do so, subject to the following conditions: |
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The above copyright notice and this permission notice shall be included |
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in all copies or substantial portions of the Software. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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DEALINGS IN THE SOFTWARE. |
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*/ |
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#ifdef MAGNUM_TARGET_GL |
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/** @file |
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* @brief Function @ref Magnum::MeshTools::fullScreenTriangle() |
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*/ |
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#endif |
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#include "Magnum/configure.h" |
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#ifdef MAGNUM_TARGET_GL |
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#include "Magnum/GL/GL.h" |
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#include "Magnum/MeshTools/visibility.h" |
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namespace Magnum { namespace MeshTools { |
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/** |
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@brief Full screen triangle mesh |
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Returns a pre-configured mesh along with vertex buffer which can be used for |
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full-screen post-processing effects. The mesh is a single triangle covering |
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whole screen area (@f$ (-1, -1) - (1, 1) @f$ in both dimensions) and provides |
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only vertex positions, as other attributes (such as texture coordinates) can be |
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calculated from them. The vertex positions are, in order: |
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@f[ |
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\begin{pmatrix} -1 \\ 1 \end{pmatrix}, |
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\begin{pmatrix} -1 \\ -3 \end{pmatrix}, |
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\begin{pmatrix} 3 \\ 1 \end{pmatrix} |
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@f] |
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Based on the @p version parameter, on OpenGL 2.1, OpenGL ES 2.0 and WebGL 1 the |
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vertex positions are passed explicitly as attribute @cpp 0 @ce, contained in |
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a vertex buffer owned by the mesh. On OpenGL 3.0+, OpenGL ES 3.0+ and WebGL 2 |
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the mesh is attribute-less and the vertex positions can be calculated using the |
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@glsl gl_VertexID @ce builtin shader variable. |
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Calculating positions in the shader in a portable way can be done like this. |
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For OpenGL 2.1 and OpenGL ES 2.0 you then need to bind location of the |
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`position` attribute to @cpp 0 @ce. |
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@code{.glsl} |
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#if (!defined(GL_ES) && __VERSION__ >= 130) || (defined(GL_ES) && __VERSION__ >= 300) |
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#define NEW_GLSL |
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#endif |
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#ifndef NEW_GLSL |
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attribute lowp vec4 position; |
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#endif |
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void main() { |
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#ifdef NEW_GLSL |
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gl_Position = vec4((gl_VertexID == 2) ? 3.0 : -1.0, |
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(gl_VertexID == 1) ? -3.0 : 1.0, 0.0, 1.0); |
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#else |
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gl_Position = position; |
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#endif |
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} |
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@endcode |
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@note This function is available only if Magnum is compiled with |
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@ref MAGNUM_TARGET_GL enabled (done by default). See @ref building-features |
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for more information. |
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*/ |
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GL::Mesh MAGNUM_MESHTOOLS_EXPORT fullScreenTriangle(GL::Version version); |
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/** @overload |
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This function implicitly uses current context version. |
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@note This function is available only if Magnum is compiled with |
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@ref MAGNUM_TARGET_GL enabled (done by default). See @ref building-features |
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for more information. |
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*/ |
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GL::Mesh MAGNUM_MESHTOOLS_EXPORT fullScreenTriangle(); |
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#else |
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#error this header is available only in the OpenGL build |
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#endif |
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}} |
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#endif
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