2D Outline Shader (SpriteRender vs Quad)

SUGBOERIE

I've got a pretty simple outline shader for 2D sprites going. If alpha pixel, look for surrounding pixels for non alpha pixel (see code below).

It works fine on a quad (left) but not on SpriteRenderer (right). I need it to work with sprite renderers in Unity. It's like the SpriteRenderer creates a different mesh based on the sprite/texture used in it. Anyone know what I'm missing!?

fixed4 SampleSpriteTexture (float2 uv)
			{
				fixed4 color = tex2D (_MainTex, uv);
				return color;
			}

			fixed4 frag(v2f IN) : COLOR
			{
				fixed4 c = SampleSpriteTexture (IN.texcoord) * IN.color;
				c.rgb *= c.a;
				
				fixed4 outlineC = _OutlineColor;
                outlineC.rgb *= outlineC.a;
                //outlineC.a *= ceil(c.a);

                if (c.a == 0.0)
				{
                    fixed upAlpha = SampleSpriteTexture ( IN.texcoord + fixed2(0, _OutlineThickness)).a;
                    fixed downAlpha = SampleSpriteTexture ( IN.texcoord - fixed2(0, _OutlineThickness)).a;
                    fixed rightAlpha = SampleSpriteTexture ( IN.texcoord + fixed2(_OutlineThickness, 0)).a;
                    fixed leftAlpha = SampleSpriteTexture ( IN.texcoord - fixed2(_OutlineThickness, 0)).a;
                    
                    fixed upRightAlpha = SampleSpriteTexture ( IN.texcoord - fixed2(_OutlineThickness, _OutlineThickness)).a;
                    fixed upLeftAlpha = SampleSpriteTexture ( IN.texcoord - fixed2(_OutlineThickness, -_OutlineThickness)).a;
                    fixed downRightAlpha = SampleSpriteTexture ( IN.texcoord - fixed2(-_OutlineThickness, _OutlineThickness)).a;
                    fixed downLeftAlpha = SampleSpriteTexture ( IN.texcoord - fixed2(-_OutlineThickness, -_OutlineThickness)).a;
				
                
				    if (upAlpha != 0.0|| downAlpha != 0.0 || rightAlpha != 0.0 || leftAlpha != 0.0 || upRightAlpha != 0.0 || upLeftAlpha != 0.0 || downLeftAlpha != 0.0 || downRightAlpha != 0.0)
				        return outlineC;    
				}
				
				return c;
			}

SUGBOERIE

I got it. It was an option on the sprite import settings.