OpenGL2: Use an OpenGL 3.2 core context if available.

code/renderergl2/glsl/generic_fp.glsl

@@ -1,5 +1,7 @@
 uniform sampler2D u_DiffuseMap;
 
+uniform int       u_AlphaTest;
+
 varying vec2      var_DiffuseTex;
 
 varying vec4      var_Color;
@@ -8,5 +10,24 @@ varying vec4      var_Color;
 void main()
 {
 	vec4 color  = texture2D(u_DiffuseMap, var_DiffuseTex);
-	gl_FragColor = color * var_Color;
+
+	float alpha = color.a * var_Color.a;
+	if (u_AlphaTest == 1)
+	{
+		if (alpha == 0.0)
+			discard;
+	}
+	else if (u_AlphaTest == 2)
+	{
+		if (alpha >= 0.5)
+			discard;
+	}
+	else if (u_AlphaTest == 3)
+	{
+		if (alpha < 0.5)
+			discard;
+	}
+	
+	gl_FragColor.rgb = color.rgb * var_Color.rgb;
+	gl_FragColor.a = alpha;
 }