Merge pull request #229 from EVAST9919/triangles-fix

Remove dFdx/dFdy usage in TriangleBorder shader

osu.Game.Resources/Shaders/sh_TriangleBorder.fs

@@ -7,6 +7,7 @@ varying highp vec2 v_TexCoord;
 
 uniform lowp sampler2D m_Sampler;
 uniform mediump float thickness;
+uniform highp float texelSize;
 
 highp float dstToLine(highp vec2 start, highp vec2 end, highp vec2 pixelPos)
 {
@@ -33,8 +34,6 @@ void main(void)
     highp vec2 resolution = v_TexRect.zw - v_TexRect.xy;
     highp vec2 pixelPos = (v_TexCoord - v_TexRect.xy) / resolution;
 
-    highp float texelSize = max(abs(dFdx(pixelPos.x)), abs(dFdy(pixelPos.y))) * 1.5;
-
     if (!insideTriangle(pixelPos))
     {
         gl_FragColor = vec4(0.0);