From f0db90c8efbd07140380fe0239973d32232875c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Wed, 5 Jun 2013 14:35:51 +0200
Subject: [PATCH] Added ES2-only support for GL_LUMINANCE{,_ALPHA}.

It is deprecated, but many ES2 implementations don't support
EXT_texture_rg, thus this is the only way to have single- and
two-component textures without wasting precious memory. The enum value
isn't exposed on desktop OpenGL and ES3. GL_ALPHA is not supported, as
it doesn't bring any new functionality (it is also single-component
and thus can be interchanged with GL_LUMINANCE).
---
 doc/unsupported.dox   |  2 --
 src/AbstractImage.cpp |  6 ++++++
 src/ImageFormat.cpp   |  6 ++++++
 src/ImageFormat.h     | 24 +++++++++++++++++++++++-
 src/TextureFormat.h   | 25 +++++++++++++++++++++++++
 5 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/doc/unsupported.dox b/doc/unsupported.dox
index 85a52c830..0c6efc4ec 100644
--- a/doc/unsupported.dox
+++ b/doc/unsupported.dox
@@ -29,8 +29,6 @@ add any performance gains, is not supported in %Magnum.
 
 @section unsupported-features Unsupported features
 
-- Luminance texture formats (OpenGL ES) are not supported, as they are
-  deprecated in OpenGL ES 3.0 and not present in core desktop OpenGL.
 - Fixed precision data types (OpenGL ES) are not supported, as they occupy the
   same memory as floats and they aren't faster than floats on current hardware
   anymore.
diff --git a/src/AbstractImage.cpp b/src/AbstractImage.cpp
index 253f2ec37..0e3af2904 100644
--- a/src/AbstractImage.cpp
+++ b/src/AbstractImage.cpp
@@ -99,11 +99,17 @@ std::size_t AbstractImage::pixelSize(ImageFormat format, ImageType type) {
         case ImageFormat::Blue:
         case ImageFormat::GreenInteger:
         case ImageFormat::BlueInteger:
+        #endif
+        #ifdef MAGNUM_TARGET_GLES2
+        case ImageFormat::Luminance:
         #endif
             return 1*size;
         case ImageFormat::RG:
         #ifndef MAGNUM_TARGET_GLES2
         case ImageFormat::RGInteger:
+        #endif
+        #ifdef MAGNUM_TARGET_GLES2
+        case ImageFormat::LuminanceAlpha:
         #endif
             return 2*size;
         case ImageFormat::RGB:
diff --git a/src/ImageFormat.cpp b/src/ImageFormat.cpp
index 014cf25eb..0d8d1fb88 100644
--- a/src/ImageFormat.cpp
+++ b/src/ImageFormat.cpp
@@ -37,7 +37,13 @@ Debug operator<<(Debug debug, ImageFormat value) {
         _c(Green)
         _c(Blue)
         #endif
+        #ifdef MAGNUM_TARGET_GLES2
+        _c(Luminance)
+        #endif
         _c(RG)
+        #ifdef MAGNUM_TARGET_GLES2
+        _c(LuminanceAlpha)
+        #endif
         _c(RGB)
         _c(RGBA)
         #ifndef MAGNUM_TARGET_GLES
diff --git a/src/ImageFormat.h b/src/ImageFormat.h
index 23b2a58f8..9420da939 100644
--- a/src/ImageFormat.h
+++ b/src/ImageFormat.h
@@ -68,8 +68,18 @@ enum class ImageFormat: GLenum {
      *      available in OpenGL ES.
      */
     Blue = GL_BLUE,
+    #endif
 
-    /** @todo GL_ALPHA? */
+    #if defined(MAGNUM_TARGET_GLES2) || defined(DOXYGEN_GENERATING_OUTPUT)
+    /**
+     * Floating-point luminance channel. The value is used for all RGB
+     * channels.
+     * @deprecated Included for compatibility reasons only, use
+     *      @ref Magnum::ImageFormat "ImageFormat::Red" instead.
+     * @requires_gles20 Not available in ES 3.0 or desktop OpenGL. Use
+     *      @ref Magnum::ImageFormat "ImageFormat::Red" instead.
+     */
+    Luminance = GL_LUMINANCE,
     #endif
 
     /**
@@ -84,6 +94,18 @@ enum class ImageFormat: GLenum {
     RG = GL_RG_EXT,
     #endif
 
+    #if defined(MAGNUM_TARGET_GLES2) || defined(DOXYGEN_GENERATING_OUTPUT)
+    /**
+     * Floating-point luminance and alpha channel. First value is used for all
+     * RGB channels, second value is used for alpha channel.
+     * @deprecated Included for compatibility reasons only, use
+     *      @ref Magnum::ImageFormat "ImageFormat::RG" instead.
+     * @requires_gles20 Not available in ES 3.0 or desktop OpenGL. Use
+     *      @ref Magnum::ImageFormat "ImageFormat::RG" instead.
+     */
+    LuminanceAlpha = GL_LUMINANCE_ALPHA,
+    #endif
+
     /**
      * Floating-point RGB.
      * @requires_gl Can't be used for framebuffer reading in OpenGL ES.
diff --git a/src/TextureFormat.h b/src/TextureFormat.h
index 7857540f7..f27d2e864 100644
--- a/src/TextureFormat.h
+++ b/src/TextureFormat.h
@@ -475,7 +475,32 @@ enum class TextureFormat: GLenum {
      * @requires_gl Packed 8bit types are not available in OpenGL ES.
      */
     R3B3G2 = GL_R3_G3_B2,
+    #endif
+
+    #if defined(MAGNUM_TARGET_GLES2) || defined(DOXYGEN_GENERATING_OUTPUT)
+    /**
+     * Luminance, normalized unsigned, single value used for all RGB channels.
+     * Size implementation-dependent.
+     * @deprecated Included for compatibility reasons only, use
+     *      @ref Magnum::TextureFormat "TextureFormat::R8" instead.
+     * @requires_gles20 Not available in ES 3.0 or desktop OpenGL. Use
+     *      @ref Magnum::TextureFormat "TextureFormat::R8" instead.
+     */
+    Luminance = GL_LUMINANCE,
+
+    /**
+     * Floating-point luminance and alpha channel. First value is used for all
+     * RGB channels, second value is used for alpha channel. Size
+     * implementation-dependent.
+     * @deprecated Included for compatibility reasons only, use
+     *      @ref Magnum::TextureFormat "TextureFormat::RG" instead.
+     * @requires_gles20 Not available in ES 3.0 or desktop OpenGL. Use
+     *      @ref Magnum::TextureFormat "TextureFormat::RG" instead.
+     */
+    LuminanceAlpha = GL_LUMINANCE_ALPHA,
+    #endif
 
+    #ifndef MAGNUM_TARGET_GLES
     /**
      * RGB, each component normalized unsigned 4bit.
      * @requires_gl Packed 12bit types are not available in OpenGL ES.