[1.10.2][UNSOLVED] Help With Custom OpenGL Shader

[Kaiodenic]

Hey! I made a GLSL shader in C++ a while back which takes a model (.obj) and paints it using an a skybox-like cubemap. It would also mix that on a 50/50 ratio with a standard texture it had. Made it look really nice and mystical. I've spent hours trying to find out how to apply custom shaders to Forge custom model blocks in Java and I'm no closer replicating that effect in Minecraft. How would I override the renderer and shader for my block? How would I make it use a .obj file (any TileEntitySpecialRenderer code I've seen uses block ModelRenderers in a ModelBase extending class) ?

 

I'm new new to Minecraft modding (only just came back to it a week ago) but I'm definitely not new to programming. Any help would be greatly appreciated!

Edited April 8, 2017 by Kaiodenic

[OreCruncher]

I would also be interested in a decent tutorial on shaders RE: Minecraft.

[Matryoshika]

  On 4/8/2017 at 1:38 PM, Kaiodenic said:

How would I make it use a .obj file

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To render .Obj models:

Call OBJLoader.INSTANCE.addDomain(modid) before you register your models, either in preInit or preferably in the ModelRegistryEvent.

After that, you can create your blockstate/model json as normal, but remember to point the variant to modid:somename.obj

The .mtl file also has to be in the same folder as the .obj, and share the same name (supermodel.obj & supermodel.mtl, for example)

Edited April 8, 2017 by Matryoshika

[Kaiodenic]

I know how to render .obj models in a typical situation. I was asking how it's done in a TileEntitySpecialRenderer because it seems like that's the only way to add custom OpenGL code to  it.

[Matryoshika]

  On 4/8/2017 at 6:40 PM, Kaiodenic said:

I know how to render .obj models in a typical situation. I was asking how it's done in a TileEntitySpecialRenderer because it seems like that's the only way to add custom OpenGL code to  it.

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Getting a BakedModel object
Rendering BakedModel

[Kaiodenic]

This should help a lot. Thank you!

 

As for the other points, does anyone know how to the renderer to use a custom shader? The code I've seen thus far was pure Java and only enabled/disabled effects used by vanilla, not using fully custom-written shaders. For my project I specifically need to override the fragment shader.

[Elix_x]

  On 4/8/2017 at 7:50 PM, Kaiodenic said:

As for the other points, does anyone know how to the renderer to use a custom shader? The code I've seen thus far was pure Java and only enabled/disabled effects used by vanilla, not using fully custom-written shaders. For my project I specifically need to override the fragment shader.

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Vanilla does not support custom shaders by itself (except ones activated when you spectate as a spider/creeper/enderman). So you have to use LWJGL and Open GL directly. But be ready to either completely change the way you draw model in-code or the way your shaders accept data. Because how vanilla MC pushes stuff to GL and how shaders normally work do not match at all.

[Kaiodenic]

  On 4/8/2017 at 8:54 PM, Elix_x said:

Vanilla does not support custom shaders by itself (except ones activated when you spectate as a spider/creeper/enderman). So you have to use LWJGL and Open GL directly. But be ready to either completely change the way you draw model in-code or the way your shaders accept data. Because how vanilla MC pushes stuff to GL and how shaders normally work do not match at all.

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Fair enough, I'm alright with that. Would you happen to know where Minecraft initially pushes things to OpenGL based on what it is (block type, or block/entity)?

Unless it uses the same settings for everything, in which case I'll probably have to pass. I feel like changing that would make it incompatible with a lot of mods.

Edited April 8, 2017 by Kaiodenic

[Elix_x]

  On 4/8/2017 at 9:21 PM, Kaiodenic said:

Fair enough, I'm alright with that. Would you happen to know where Minecraft initially pushes things to OpenGL based on what it is (block type, or block/entity)?

Unless it uses the same settings for everything, in which case I'll probably have to pass. I feel like changing that would make it incompatible with a lot of mods.

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It would not make it incompatible with other mods. Just make sure to "save" GL state before you start rendering with shaders to restore it after.

 

First, create custom shader helper class, that sets all uniforms, uploads shader, binds, etc... Now, if you want your shader to be customizable with resource packs, implement and register IResourceManagerReloadListener, in which you load/reload shaders. Otherwise, just upload it in post init.

 

Now, when your TESR is called, bind your shader, render OBJ model and then unbind the shader.

Seems easy? It isn't.

 

For the rendering part, as i said previously, you can either change how you upload things to shader or how you shader reads things.

The first option is easier. Just create all necessary classes using modern GL functions - Mesh, Matrix Handler, etc... For the mesh, it is recommended to use VAO with indexed position VBO and non-indexed texture & normal VBOs, because that's how OBJ model is encoded. Now you just have to write your own OBJ reader and compiler (which compiles it into a mesh). There are plenty of tutorials online on how to do this.

Read, compile and upload your model into mesh either in resource reload listener or post init and render this mesh in TESR.

 

Now just make sure that you inform users of your mod that at least GL3 support is required  (all modern graphics cards support it, so no much worries).

 

Note: Rendering performance can be improved very much, by binding shader once... But i'll let you think on how that can be done  .