Support for more vertex attributes (e.g. tangents, binormals)

[Arparso]

First of all, great tool!

As far as I can tell, it only supports a limited set of per-vertex attributes, though: Positions, normals and one set of texture coordinates.

I tried implementing a simple normal mapping shader, which requires tangent and binormal vectors for each vertex. Using the HLSL shader semantics for tangents and binormals did not work, though - the float3 vectors were all 0.

The tool also does not seem to respect the semantics in my HLSL shader at all, it always stores position in the first attribute, normals in the second attribute and texture coordinate in the thrid. E.g.

struct VSInput { float3 Position : POSITION; float2 TexCoord : TEXCOORD0; float3 Normal : NORMAL; };

This does not work as expected: "TexCoord" will contain the normal instead and "Normal" will contain texture coordinates.

It would be nice if we could configure the vertex attributes that are supplied to the shader, including ones that are not supported right now (e.g. tangents, binormals, vertex color or multiple sets of texture coordinates).

(if there is a way to do that, already, I haven't found it)

[dfranx]

Thanks!

Currently tangents and binormals aren't implemented. I could definitely try adding those two in the v1.2.2.

The semantics are ignored and don't actually matter. The reason for this is that I am transcompiling HLSL to GLSL. But I guess I could internally reorganize the inputs during HLSL->GLSL conversion if I detect some semantic such as "POSITION", etc... I am not promising anything though. I will look more into this and see if it is possible (I believe that it should be possible).

In the Direct3D 11 version of SHADERed there was an "Input layout manager" option. You could modify the inputs. I removed it because I thought it made SHADERed more difficult to get started with. I guess I could reintroduce that feature again now.

Also, how would vertex color attribute work? Do I allow the user to set the color for all vertices or? And do you have an example/tutorial on how multiple sets of texture coordinates are used? I've seen this mentioned before but haven't looked into it too much.

[Arparso]

Having access to tangents and binormals would be very helpful to me.

Semantics support would be nice, as well, but not a must have for me - as long as I know how to access the correct vertex attribute. I was just caught off-guard this time, because I assumed I had made some error in my calculations, when it was in fact faulty/missing vertex data.

"Input layout manager" would be nice. I've used ATI Rendermonkey in the past (years ago) and they had something similar to configure the vertexbuffer layout to match your requirements. Maybe default to some sensible "auto" mode that mimics the current behaviour, but allow manual configuration of the layout, if users want to.

With regards to vertex color: I think that needs to come from the model itself. Probably not useful for the built-in geometry, but for loading external models. I think you're using Assimp to load these models? That should be able to extract vertex colors if it finds any. I don't personally use vertex color right now, but someone else might.

Multiple texture coordinates: I haven't ever used them, either, but I'm also just an amateur/hobbyist. I guess this could be useful if applying more than one texture to a model, e.g. a coarse color map and then some (repeated) detail map for finer details. Or you'd store some other material/object properties in these extra UVs.

Right now I'd only need tangents (and binormals, if possible). Depending on how far you want to take this tool, you might want to consider the other types of attributes and custom input layouts, too.

[dfranx]

Thanks for the detailed feedback. I will try to include these features (input layout manager, semantics, binormals, tangents, etc...) next week. Should come out with the v1.2.2

[dfranx]

Hi! The feature is implemented in the v1.2.2.

I've implemented input layouts, bitangents, tangents and vertex colors.

The semantics currently don't work as there isn't, as far as I know, an easy way to get input variable's semantic. I will implement semantics when I learn how to properly use glslang's AST tree.
But you can change the locations of vertex shader's input variables (throught the input layout manager) and "emulate" semantics that way.

I will implement multiple texture coordinates but not right now.

Also, I hope that the tangents and bitangents/binormals have proper values.
I used this tutorial to calculate them: http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-13-normal-mapping/
And here is my code in case that the values are not proper: https://github.com/dfranx/SHADERed/blob/master/Engine/GeometryFactory.cpp#L113-L172

Also, could you provide a screenshot of your normal map shader if tangents and bitangents in SHADERed work? I would like to add it to the README.md