gl: add yuv to rgb shader

result color is wrong, shader seems right. may be some mistakes in c++
code

src/libQtAV.pro

@@ -15,7 +15,8 @@ PROJECTROOT = $$PWD/..
 preparePaths($$OUT_PWD/../out)
 
 
-RESOURCES += ../i18n/QtAV.qrc
+RESOURCES += ../i18n/QtAV.qrc \
+    shaders/shaders.qrc
 
 win32 {
     RC_FILE = $${PROJECTROOT}/res/QtAV.rc
@@ -111,6 +112,7 @@ config_gl {
     SOURCES += GLWidgetRenderer.cpp
     HEADERS += QtAV/private/GLWidgetRenderer_p.h
     SDK_HEADERS += QtAV/GLWidgetRenderer.h
+    OTHER_FILES += shaders/yuv_rgb.f.glsl
 }
 config_dxva {
     DEFINES *= QTAV_HAVE_DXVA=1

src/shaders/shaders.qrc

@@ -0,0 +1,5 @@
+<RCC>
+    <qresource prefix="/shaders">
+        <file>yuv_rgb.f.glsl</file>
+    </qresource>
+</RCC>

src/shaders/yuv_rgb.f.glsl

@@ -0,0 +1,36 @@
+#ifdef GL_ES
+// Set default precision to medium
+precision mediump int;
+precision mediump float;
+#else
+#define highp
+#define mediump
+#define lowp
+#endif
+
+// u_TextureN: yuv. use array?
+uniform sampler2D u_Texture0;
+uniform sampler2D u_Texture1;
+uniform sampler2D u_Texture2;
+varying lowp vec2 v_TexCoords;
+
+//http://en.wikipedia.org/wiki/YUV calculation used
+//http://www.fourcc.org/fccyvrgb.php
+//GLSL: col first
+// use bt601
+const mat4 colorMatrix = mat4(1, 1, 1, 0,
+                              0, -0.344, 1.773, 0,
+                              1.403, -0.714, 0, 0,
+                              0, 0, 0, 1)
+                        * mat4(1, 0, 0, 0,
+                               0, 1, 0, 0,
+                               0, 0, 1, 0,
+                               0, -0.5, -0.5, 1);
+void main()
+{
+    gl_FragColor = clamp(colorMatrix* vec4(texture2D(u_Texture0, v_TexCoords).r,
+                                           texture2D(u_Texture1, v_TexCoords).r,
+                                           texture2D(u_Texture2, v_TexCoords).r,
+                                           1)
+                      , 0.0, 1.0);
+}