effects: Add standard effect file

There are a number of duplicate shader routines we should combine into a single shader to save disk space, and remove unexpected errors in one copy but not the other.

CMakeLists.txt

@@ -1174,6 +1174,7 @@ list(APPEND PROJECT_DATA
 	"data/effects/color_conversion_rgb_yuv.effect"
 	"data/effects/mipgen.effect"
 	"data/effects/pack-unpack.effect"
+	"data/effects/standard.effect"
 	"data/effects/shared.effect"
 	"data/locale/en-US.ini"
 )

data/effects/shared.effect

@@ -16,6 +16,9 @@ uniform float4x4 ViewProj;
 //------------------------------------------------------------------------------
 // Samplers
 //------------------------------------------------------------------------------
+sampler_state BlankSampler {
+};
+
 sampler_state PointRepeatSampler {
 	Filter = Point;
 	AddressU = Repeat;

data/effects/standard.effect

@@ -0,0 +1,27 @@
+#include "shared.effect"
+
+uniform texture2D Channel0;
+uniform texture2D Channel1;
+
+//------------------------------------------------------------------------------
+// Technique: Restore Alpha
+//------------------------------------------------------------------------------
+// Parameters:
+// - Channel0: RGBX Texture
+// - Channel1: XXXA Texture
+
+float4 PSRestoreAlpha(VertexData vtx) : TARGET {
+	float4 rgbx = Channel0.Sample(BlankSampler, vtx.uv);
+	float4 xxxa = Channel1.Sample(BlankSampler, vtx.uv);
+	rgbx.a = xxxa.a;
+	return rgbx;
+};
+
+technique RestoreAlpha
+{
+	pass
+	{
+		vertex_shader = DefaultVertexShader(vtx);
+		pixel_shader = PSRestoreAlpha(vtx);
+	};
+};