diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index 75fd11511ae1..d8ed20bc380c 100644
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,21 @@
+2017-10-24  Miguel Gomez  <magomez@igalia.com>
+
+        [GTK][X11] Windy.com shows always straight wind lines
+        https://bugs.webkit.org/show_bug.cgi?id=176718
+
+        Reviewed by Carlos Garcia Campos.
+
+        WebGL's GL_LUMINANCE_ALPHA format is not available in OpenGL when using a version >= 3.2
+        and a core profile. In that case, we need to replace it with GL_RG and swizzle the color
+        components appropriately.
+
+        No new behavior.
+
+        * platform/graphics/opengl/GraphicsContext3DOpenGL.cpp:
+        (WebCore::GraphicsContext3D::texImage2D):
+        * platform/graphics/opengl/GraphicsContext3DOpenGLCommon.cpp:
+        (WebCore::GraphicsContext3D::texSubImage2D):
+
 2017-10-23  Zalan Bujtas  <zalan@apple.com>
 
         Call FrameView::scheduleSelectionUpdate when selection needs repainting after layout instead of setting the RenderView dirty.
diff --git a/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGL.cpp b/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGL.cpp
index 553a8970d304..0eebeb16a4a7 100644
--- a/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGL.cpp
+++ b/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGL.cpp
@@ -386,13 +386,30 @@ bool GraphicsContext3D::texImage2D(GC3Denum target, GC3Dint level, GC3Denum inte
         openGLFormat = GL_RGB;
 #endif
 
-    if (m_usingCoreProfile && openGLInternalFormat == ALPHA) {
-        // We are using a core profile. This means that GL_ALPHA, which is a valid format in WebGL for texImage2D
-        // is not supported in OpenGL. It needs to be backed with a GL_RED plane. We change the formats to GL_RED
-        // (both need to be GL_ALPHA in WebGL) and instruct the texture to swizzle the red component values with
-        // the the alpha component values.
-        openGLInternalFormat = openGLFormat = RED;
-        texParameteri(target, TEXTURE_SWIZZLE_A, RED);
+    if (m_usingCoreProfile) {
+        // There are some format values used in WebGL that are deprecated when using a core profile, so we need
+        // to adapt them.
+        switch (openGLInternalFormat) {
+        case ALPHA:
+            // The format is a simple component containing an alpha value. It needs to be backed with a GL_RED plane.
+            // We change the formats to GL_RED (both need to be GL_ALPHA in WebGL) and instruct the texture to swizzle
+            // the red component values with the alpha component values.
+            openGLInternalFormat = openGLFormat = RED;
+            texParameteri(target, TEXTURE_SWIZZLE_A, RED);
+            break;
+        case LUMINANCE_ALPHA:
+            // The format has 2 components, an alpha one and a luminance one (same value for red, green and blue).
+            // It needs to be backed with a GL_RG plane, using the red component for the colors and the green component
+            // for alpha. We change the formats to GL_RG and swizzle the components.
+            openGLInternalFormat = openGLFormat = RG;
+            texParameteri(target, TEXTURE_SWIZZLE_R, RED);
+            texParameteri(target, TEXTURE_SWIZZLE_G, RED);
+            texParameteri(target, TEXTURE_SWIZZLE_B, RED);
+            texParameteri(target, TEXTURE_SWIZZLE_A, GREEN);
+            break;
+        default:
+            break;
+        }
     }
 
     texImage2DDirect(target, level, openGLInternalFormat, width, height, border, openGLFormat, type, pixels);
diff --git a/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGLCommon.cpp b/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGLCommon.cpp
index 023e843ceafb..b0932d1dcc46 100644
--- a/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGLCommon.cpp
+++ b/Source/WebCore/platform/graphics/opengl/GraphicsContext3DOpenGLCommon.cpp
@@ -1807,10 +1807,21 @@ void GraphicsContext3D::texSubImage2D(GC3Denum target, GC3Dint level, GC3Dint xo
         type = GL_HALF_FLOAT_ARB;
 #endif
 
-    if (m_usingCoreProfile && format == ALPHA) {
-        // We are using a core profile. This means that GL_ALPHA, which is a valid format in WebGL for texSubImage2D
-        // is not supported in OpenGL. We are using GL_RED to back GL_ALPHA, so do it here as well.
-        format = RED;
+    if (m_usingCoreProfile)  {
+        // There are some format values used in WebGL that are deprecated when using a core profile, so we need
+        // to adapt them, as we do in GraphicsContext3D::texImage2D().
+        switch (format) {
+        case ALPHA:
+            // We are using GL_RED to back GL_ALPHA, so do it here as well.
+            format = RED;
+            break;
+        case LUMINANCE_ALPHA:
+            // We are using GL_RG to back GL_LUMINANCE_ALPHA, so do it here as well.
+            format = RG;
+            break;
+        default:
+            break;
+        }
     }
 
     // FIXME: we will need to deal with PixelStore params when dealing with image buffers that differ from the subimage size.