Modify the opengl version of the blur shader to match the d3d11 version

data/shaders/gaussian_1d_texture.effect

@@ -31,21 +31,33 @@ struct VertData {
     float2 uv : TEXCOORD0;
 };
 
+float4 PremulToStraight(float4 col)
+{
+	col.rgb = saturate(col.rgb / max(col.a, 0.0001f));
+	return col;
+}
+
+float4 StraightToPremul(float4 col)
+{
+	col.rgb *= col.a;
+	return col;
+}
+
 VertData mainTransform(VertData v_in)
 {
     v_in.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
     return v_in;
 }
 
-float4 mainImage(VertData v_in) : TARGET
+float4 SampleBlur(float2 uv)
 {
     // DO THE BLUR
     // 1. Sample incoming pixel, multiply by weight[0]
-    // float4 test = kernel_texture.Sample(tableSampler, float2(v_in.uv[0], 0.0));
+    // float4 test = kernel_texture.Sample(tableSampler, float2(uv[0], 0.0));
     // float max_radius = kernel_texture.Sample(tableSampler, float2(1.0, 0.0))[1];
     // return float4(test.g/max_radius, test.g/max_radius, test.g/max_radius, 1.0);
     float weight = kernel_texture.Sample(tableSampler, float2(0.0f, 0.0f))[0];
-    float4 col = image.Sample(textureSampler, v_in.uv) * weight;
+    float4 col = image.Sample(textureSampler, uv) * weight;
     float total_weight = weight;
 
     // 2. March out from incoming pixel, multiply by corresponding weight.
@@ -55,18 +67,71 @@ float4 mainImage(VertData v_in) : TARGET
         weight = kernel_values[0];
         float offset = kernel_values[1];
         total_weight += 2.0f*weight;
-        col += image.Sample(textureSampler, v_in.uv + (offset * texel_step)) * weight;
-        col += image.Sample(textureSampler, v_in.uv - (offset * texel_step)) * weight;
+        col += image.Sample(textureSampler, uv + (offset * texel_step)) * weight;
+        col += image.Sample(textureSampler, uv - (offset * texel_step)) * weight;
     }
     col /= total_weight;
     return col;
 }
 
-technique Draw
+float4 mainStraightToPremul(VertData v_in) : TARGET
 {
-    pass
-    {
-        vertex_shader = mainTransform(v_in);
-        pixel_shader = mainImage(v_in);
-    }
+	return StraightToPremul(image.Sample(textureSampler, v_in.uv));
+}
+
+float4 mainPremulToStraight(VertData v_in) : TARGET
+{
+	return PremulToStraight(image.Sample(textureSampler, v_in.uv));
+}
+
+float4 mainBlur(VertData v_in) : TARGET
+{
+	// Input image is premultiplied
+	float4 col = SampleBlur(v_in.uv);
+	// Output is still premultiplied
+	return col;
+}
+
+float4 mainBlurPremulToStraight(VertData v_in) : TARGET
+{
+    	// Input image is premultiplied
+	float4 col = SampleBlur(v_in.uv);
+	// Output is straight alpha
+	return PremulToStraight(col);
+}
+
+technique DrawStraightToPremul
+{
+	pass
+	{
+		vertex_shader = mainTransform(v_in);
+		pixel_shader = mainStraightToPremul(v_in);
+	}
+}
+
+technique DrawPremulToStraight
+{
+	pass
+	{
+		vertex_shader = mainTransform(v_in);
+		pixel_shader = mainPremulToStraight(v_in);
+	}
+}
+
+technique DrawBlur
+{
+	pass
+	{
+		vertex_shader = mainTransform(v_in);
+		pixel_shader = mainBlur(v_in);
+	}
+}
+
+technique DrawBlurPremulToStraight
+{
+	pass
+	{
+		vertex_shader = mainTransform(v_in);
+		pixel_shader = mainBlurPremulToStraight(v_in);
+	}
 }