ARB_texture_rg: Add GL_RED as a valid GL_DEPTH_TEXTURE_MODE

src/mesa/main/texparam.c

@@ -351,7 +351,8 @@ set_tex_parameteri(GLcontext *ctx,
       if (ctx->Extensions.ARB_depth_texture &&
           (params[0] == GL_LUMINANCE ||
            params[0] == GL_INTENSITY ||
-           params[0] == GL_ALPHA)) {
+           params[0] == GL_ALPHA ||
+	   (ctx->Extensions.ARB_texture_rg && params[0] == GL_RED))) {
          if (texObj->DepthMode != params[0]) {
             flush(ctx, texObj);
             texObj->DepthMode = params[0];

src/mesa/swrast/s_texfilter.c

@@ -3051,6 +3051,9 @@ sample_depth_texture( GLcontext *ctx,
          case GL_ALPHA:
             ASSIGN_4V(texel[i], 0.0F, 0.0F, 0.0F, result);
             break;
+         case GL_RED:
+            ASSIGN_4V(texel[i], result, 0.0F, 0.0F, 1.0F);
+            break;
          default:
             _mesa_problem(ctx, "Bad depth texture mode");
          }