Pixel storage support, part 3: EXT_unpack_subimage and NV_pack_subimage.

ES 2.0 extensions to match ES3/desktop functionality. The enums from
NV_pack_subimage are not available in gl.xml from Khronos, I would need
to use hardcoded value.

doc/opengl-support.dox

@@ -301,6 +301,7 @@ Extension                                   | Status
 @es_extension{EXT,discard_framebuffer}      | done
 @es_extension2{EXT,blend_minmax,blend_minmax} | done
 @es_extension{EXT,shader_texture_lod}       | done (shading language only)
+@es_extension{EXT,unpack_subimage}          | |
 @es_extension{EXT,occlusion_query_boolean}  | done
 @es_extension{EXT,shadow_samplers}          | done
 @es_extension{EXT,texture_rg}               | done
@@ -313,6 +314,7 @@ Extension                                   | Status
 @es_extension{NV,draw_buffers}              | done
 @es_extension{NV,fbo_color_attachments}     | done
 @es_extension{NV,read_buffer}               | done
+@es_extension{NV,pack_subimage}             | |
 @es_extension{NV,draw_instanced}            | done
 @es_extension{NV,framebuffer_blit}          | done
 @es_extension{NV,framebuffer_multisample}   | done

src/Magnum/Context.cpp

@@ -326,6 +326,7 @@ const std::vector<Extension>& Extension::extensions(Version version) {
         _extension(GL,EXT,discard_framebuffer),
         _extension(GL,EXT,blend_minmax),
         _extension(GL,EXT,shader_texture_lod),
+        _extension(GL,EXT,unpack_subimage),
         _extension(GL,EXT,occlusion_query_boolean),
         _extension(GL,EXT,shadow_samplers),
         _extension(GL,EXT,texture_rg),
@@ -338,6 +339,7 @@ const std::vector<Extension>& Extension::extensions(Version version) {
         _extension(GL,NV,draw_buffers),
         _extension(GL,NV,fbo_color_attachments),
         _extension(GL,NV,read_buffer),
+        _extension(GL,NV,pack_subimage),
         _extension(GL,NV,draw_instanced),
         _extension(GL,NV,framebuffer_blit),
         _extension(GL,NV,framebuffer_multisample),

src/Magnum/Extensions.h

@@ -308,6 +308,7 @@ namespace GL {
         _extension(GL,EXT,multi_draw_arrays,        GLES200,    None) // #67
         #ifdef MAGNUM_TARGET_GLES2
         _extension(GL,EXT,shader_texture_lod,       GLES200, GLES300) // #77
+        _extension(GL,EXT,unpack_subimage,          GLES200, GLES300) // #90
         #endif
         _extension(GL,EXT,debug_label,              GLES200,    None) // #98
         _extension(GL,EXT,debug_marker,             GLES200,    None) // #99
@@ -374,6 +375,7 @@ namespace GL {
         _extension(GL,NV,read_stencil,              GLES200,    None) // #94
         _extension(GL,NV,read_depth_stencil,        GLES200,    None) // #94
         #ifdef MAGNUM_TARGET_GLES2
+        _extension(GL,NV,pack_subimage,             GLES200, GLES300) // #132
         _extension(GL,NV,draw_instanced,            GLES200, GLES300) // #141
         _extension(GL,NV,framebuffer_blit,          GLES200, GLES300) // #142
         _extension(GL,NV,framebuffer_multisample,   GLES200, GLES300) // #143

src/MagnumExternal/OpenGL/GLES2/extensions.txt

@@ -13,6 +13,7 @@ extension EXT_texture_type_2_10_10_10_REV       optional
 extension EXT_discard_framebuffer               optional
 extension EXT_blend_minmax                      optional
 extension EXT_shader_texture_lod                optional
+extension EXT_unpack_subimage                   optional
 extension EXT_occlusion_query_boolean           optional
 extension EXT_shadow_samplers                   optional
 extension EXT_texture_rg                        optional
@@ -25,6 +26,7 @@ extension EXT_draw_instanced                    optional
 extension NV_draw_buffers                       optional
 extension NV_fbo_color_attachments              optional
 extension NV_read_buffer                        optional
+extension NV_pack_subimage                      optional
 extension NV_draw_instanced                     optional
 extension NV_framebuffer_blit                   optional
 extension NV_framebuffer_multisample            optional

src/MagnumExternal/OpenGL/GLES2/flextGL.h

@@ -443,6 +443,12 @@ typedef khronos_ssize_t GLsizeiptr;
 #define GL_MIN_EXT 0x8007
 #define GL_MAX_EXT 0x8008
 
+/* GL_EXT_unpack_subimage */
+
+#define GL_UNPACK_ROW_LENGTH_EXT 0x0CF2
+#define GL_UNPACK_SKIP_ROWS_EXT 0x0CF3
+#define GL_UNPACK_SKIP_PIXELS_EXT 0x0CF4
+
 /* GL_EXT_occlusion_query_boolean */
 
 #define GL_ANY_SAMPLES_PASSED_EXT 0x8C2F

src/MagnumExternal/OpenGL/GLES2/flextGLNaCl.h

@@ -418,6 +418,12 @@ typedef khronos_ssize_t GLsizeiptr;
 #define GL_MIN_EXT 0x8007
 #define GL_MAX_EXT 0x8008
 
+/* GL_EXT_unpack_subimage */
+
+#define GL_UNPACK_ROW_LENGTH_EXT 0x0CF2
+#define GL_UNPACK_SKIP_ROWS_EXT 0x0CF3
+#define GL_UNPACK_SKIP_PIXELS_EXT 0x0CF4
+
 /* GL_EXT_occlusion_query_boolean */
 
 #define GL_ANY_SAMPLES_PASSED_EXT 0x8C2F
@@ -1667,6 +1673,11 @@ GL_APICALL void GL_APIENTRY GLES2TextureStorage3DEXT(GLuint, GLenum, GLsizei, GL
 #define GL_EXT_texture_type_2_10_10_10_REV 1
 #endif
 
+/* GL_EXT_unpack_subimage */
+#ifndef GL_EXT_unpack_subimage
+#define GL_EXT_unpack_subimage 1
+#endif
+
 /* GL_KHR_blend_equation_advanced */
 #ifndef GL_KHR_blend_equation_advanced
 #define GL_KHR_blend_equation_advanced 1