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Development Days



Some of the Leadwerks Game Engine design was originally developed to run on PC and mobile. In order to supported multiple renderers (OpenGL and OpenGLES) I implemented a system that uses an abstract base class with an API-specific class derived from that:

  • Texture
    • OpenGLTexture

All OpenGL code was contained in the OpenGLTexture class. This worked fine, and theoretically it would have allowed us to support multiple renderers within one build, like OpenGL and DirectX. In practice it's a feature that was never used, and created a lot of complicate class hierarchies, with functionality split between the base and derived classes.

In the new engine, all rendering code is completely separated in a separate thread, and we have a separate class that is a stripped-down representation of the object the programmer interfaces with:

  • Texture
  • RenderTexture

When the programmer calls a command that makes a change to the Texture object, an instruction is added to a queue of commands that is sent to the rendering thread, and their change is also made on that RenderTexture object, although not instantaneously.

Right now I am stripping out the derived classes and turning classes that were previously abstract into full classes. It's quite a big job to restructure a complex program like this but it needs to be done. Even when we switch over to Vulkan / Metal I don't see us every supporting multiple APIs within a single build, and I am glad to get rid of this aspect of the engine.

I'm also doing the same thing for physics. An Entity object in the main thread can have a PhysicsNode object that lives in the physics thread. However, this does not get created unless there is some physics command performed on the entity, like setting the mass or adding a collision shape.

Other stuff I want to change:

  • Get rid of GetClass() / GetClassName() method.
  • Get rid of Object::ModelClass etc. constants.
  • Replace all static class constants with global variables, i.e. WINDOW_FULLSCREEN instead of Window::Fullscreen.

It's actually best to declare constants with enum because then they get evaluated as a constant and can be used in array declarations and switch statements. It only needs to be declared once, in the header, but unlike a macro it stays contained within the namespace it is declared in:

enum { MAX_PHYSICS_THREADS = 32 };

The next step is to create a usable programming SDK with models, lights, scene loading, scripting, and physics. This will allow beta testers to actually start developing games. The lack of a visual editor is a challenge, but at the same time we are now using more standard file formats like DDS and GLTF, which gives us better consistency with the output of various modeling programs. I'd like to start looking at a Lua debugger for Visual Studio Code soon. There seems to be some debuggers out there already, but I have no idea how the communication between the debugger and the game is supposed to work. I invented my own network data protocol in Leadwerks and there isn't any standard I am aware of.

2D graphics in the new engine are quite different from in Leadwerks, which used drawing commands to control what gets displayed on screen. Since the rendering all occurs asynchronously on another thread, this approach does not make sense at all. I also had a problem with the GUI in this design. The GUI system uses a script with a drawing command to redraw each widget, but we don't want any Lua code running in the rendering thread.

The solution is to make 2D graphical elements persistent objects:

auto window = CreateWindow();
auto context = CreateContext(window);
auto world = CreateWorld();

//Create some 2D graphics
auto rect = CreateRect(context,10,10,200,75,true);

auto line = CreateLine(context,10,10,200,200);

auto text = CreateText(context,"Hello!",0,0,200,75,TEXT_CENTER);

while (not window->Closed())

Just like with an entity, you can set the variable to null to stop drawing the element.

while (not window->Closed())
	if (window->KeyHit(KEY_SPACE)) rect = nullptr;

2D elements can have a hierarchy, so you can create one element that gets drawn on top of another:

auto rect = CreateRect(context,10,10,200,75,true);
auto rect2 = CreateRect(rect,4,4,rect.size.x-8,rect.size.y-8,true);

We need the GUI working for some VR projects I want to use the new engine in soon. Once the items above are all working, that will give us everything we need to start working on the new editor.

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A new beta with GLTF support will be available pretty soon. 2D drawing support will take a bit longer, but it's not that hard.

We also support SVG (vector) images now so that will be interesting.

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Oh yeah, navigation is another system that needs to be worked out before we have "Blitz3D on crack".

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10 hours ago, Lethal Raptor Games said:

Looking forward to it.  Have you thought much on whether or not you will keep the actor class?

Yes, we will keep it. Multiple actors can be added to an entity, and I plan to expose C++ fields in the editor.

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I stripped out A LOT of extra classes. If I never see a double-colon (::) again it will be too soon.

  • Haha 1

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  • Blog Entries

    • By Josh in Josh's Dev Blog 2
      I started to implement quads for tessellation, and at that point the shader system reached the point of being unmanageable. Rendering an object to a shadow map and to a color buffer are two different processes that require two different shaders. Turbo introduces an early Z-pass which can use another shader, and if variance shadow maps are not in use this can be a different shader from the shadow shader. Rendering with tessellation requires another set of shaders, with one different set for each primitive type (isolines, triangles, and quads). And then each one of these needs a masked and opaque option, if alpha discard is enabled.
      All in all, there are currently 48 different shaders a material could use based on what is currently being drawn. This is unmanageable.
      To handle this I am introducing the concept of a "shader family". This is a JSON file that lists all possible permutations of a shader. Instead of setting lots of different shaders in a material, you just set the shader family one:
      shaderFamily: "PBR.json" Or in code:
      material->SetShaderFamily(LoadShaderFamily("PBR.json")); The shader family file is a big JSON structure that contains all the different shader modules for each different rendering configuration: Here are the partial contents of my PBR.json file:
      { "turboShaderFamily" : { "OPAQUE": { "default": { "base": { "vertex": "Shaders/PBR.vert.spv", "fragment": "Shaders/PBR.frag.spv" }, "depthPass": { "vertex": "Shaders/Depthpass.vert.spv" }, "shadow": { "vertex": "Shaders/Shadow.vert.spv" } }, "isolines": { "base": { "vertex": "Shaders/PBR_Tess.vert.spv", "tessellationControl": "Shaders/Isolines.tesc.spv", "tessellationEvaluation": "Shaders/Isolines.tese.spv", "fragment": "Shaders/PBR_Tess.frag.spv" }, "shadow": { "vertex": "Shaders/DepthPass_Tess.vert.spv", "tessellationControl": "Shaders/DepthPass_Isolines.tesc.spv", "tessellationEvaluation": "Shaders/DepthPass_Isolines.tese.spv" }, "depthPass": { "vertex": "Shaders/DepthPass_Tess.vert.spv", "tessellationControl": "DepthPass_Isolines.tesc.spv", "tessellationEvaluation": "DepthPass_Isolines.tese.spv" } }, "triangles": { "base": { "vertex": "Shaders/PBR_Tess.vert.spv", "tessellationControl": "Shaders/Triangles.tesc.spv", "tessellationEvaluation": "Shaders/Triangles.tese.spv", "fragment": "Shaders/PBR_Tess.frag.spv" }, "shadow": { "vertex": "Shaders/DepthPass_Tess.vert.spv", "tessellationControl": "Shaders/DepthPass_Triangles.tesc.spv", "tessellationEvaluation": "Shaders/DepthPass_Triangles.tese.spv" }, "depthPass": { "vertex": "Shaders/DepthPass_Tess.vert.spv", "tessellationControl": "DepthPass_Triangles.tesc.spv", "tessellationEvaluation": "DepthPass_Triangles.tese.spv" } }, "quads": { "base": { "vertex": "Shaders/PBR_Tess.vert.spv", "tessellationControl": "Shaders/Quads.tesc.spv", "tessellationEvaluation": "Shaders/Quads.tese.spv", "fragment": "Shaders/PBR_Tess.frag.spv" }, "shadow": { "vertex": "Shaders/DepthPass_Tess.vert.spv", "tessellationControl": "Shaders/DepthPass_Quads.tesc.spv", "tessellationEvaluation": "Shaders/DepthPass_Quads.tese.spv" }, "depthPass": { "vertex": "Shaders/DepthPass_Tess.vert.spv", "tessellationControl": "DepthPass_Quads.tesc.spv", "tessellationEvaluation": "DepthPass_Quads.tese.spv" } } } } } A shader family file can indicate a root to inherit values from. The Blinn-Phong shader family pulls settings from the PBR file and just switches some of the fragment shader values.
      { "turboShaderFamily" : { "root": "PBR.json", "OPAQUE": { "default": { "base": { "fragment": "Shaders/Blinn-Phong.frag.spv" } }, "isolines": { "base": { "fragment": "Shaders/Blinn-Phong_Tess.frag.spv" } }, "triangles": { "base": { "fragment": "Shaders/Blinn-Phong_Tess.frag.spv" } }, "quads": { "base": { "fragment": "Shaders/Blinn-Phong_Tess.frag.spv" } } } } } If you want to implement a custom shader, this is more work because you have to define all your changes for each possible shader variation. But once that is done, you have a new shader that will work with all of these different settings, which in the end is easier. I considered making a more complex inheritance / cascading schema but I think eliminating ambiguity is the most important goal in this and that should override any concern about the verbosity of these files. After all, I only plan on providing a couple of these files and you aren't going to need any more unless you are doing a lot of custom shaders. And if you are, this is the best solution for you anyways.
      Consequently, the baseShader, depthShader, etc. values in the material file definition are going away. Leadwerks .mat files will always use the Blinn-Phong shader family, and there is no way to change this without creating a material file in the new JSON material format.
      The shader class is no longer derived from the Asset class because it doesn't correspond to a single file. Instead, it is just a dumb container. A ShaderModule class derived from the Asset class has been added, and this does correspond with a single .spv file. But you, the user, won't really need to deal with any of this.
      The result of this is that one material will work with tessellation enabled or disabled, quad, triangle, or line meshes, and animated meshes. I also added an optional parameter in the CreatePlane(), CreateBox(), and CreateQuadSphere() commands that will create these primitives out of quads instead of triangles. The main reason for supporting quad meshes is that the tessellation is cleaner when quads are used. (Note that Vulkan still displays quads in wireframe mode as if they are triangles. I think the renderer probably converts them to normal triangles after the tessellation stage.)

      I also was able to implement PN Quads, which is a quad version of the Bezier curve that PN Triangles add to tessellation.

      Basically all the complexity is being packed into the shader family file so that these decisions only have to be made once instead of thousands of times for each different material.
    • By Josh in Josh's Dev Blog 0
      I'm back from I/ITSEC. This conference is basically like the military's version of GDC. VR applications built with Leadwerks took up about half of Northrop Grumman's booth. There were many interesting discussions about new technology and I received a very warm reception. I feel very positive about our new technology going forward.

      I am currently reworking the text field widget script to work with our persistent 2D objects. This is long and boring but needs to be done. Not much else to say right now.
    • By Josh in Josh's Dev Blog 4
      Here are some screenshots showing more complex interface items scaled at different resolutions. First, here is the interface at 100% scaling:

      And here is the same interface at the same screen resolution, with the DPI scaling turned up to 150%:

      The code to control this is sort of complex, and I don't care. GUI resolution independence is a complicated thing, so the goal should be to create a system that does what it is supposed to do reliably, not to make complicated things simpler at the expense of functionality.
      function widget:Draw(x,y,width,height) local scale = self.gui:GetScale() self.primitives[1].size = iVec2(self.size.x, self.size.y - self.tabsize.y * scale) self.primitives[2].size = iVec2(self.size.x, self.size.y - self.tabsize.y * scale) --Tabs local n local tabpos = 0 for n = 1, #self.items do local tw = self:TabWidth(n) * scale if n * 3 > #self.primitives - 2 then self:AddRect(iVec2(tabpos,0), iVec2(tw, self.tabsize.y * scale), self.bordercolor, false, self.itemcornerradius * scale) self:AddRect(iVec2(tabpos+1,1), iVec2(tw, self.tabsize.y * scale) - iVec2(2 * scale,-1 * scale), self.backgroundcolor, false, self.itemcornerradius * scale) self:AddTextRect(self.items[n].text, iVec2(tabpos,0), iVec2(tw, self.tabsize.y*scale), self.textcolor, TEXT_CENTER + TEXT_MIDDLE) end if self:SelectedItem() == n then self.primitives[2 + (n - 1) * 3 + 1].position = iVec2(tabpos, 0) self.primitives[2 + (n - 1) * 3 + 1].size = iVec2(tw, self.tabsize.y * scale) + iVec2(0,2) self.primitives[2 + (n - 1) * 3 + 2].position = iVec2(tabpos + 1, 1) self.primitives[2 + (n - 1) * 3 + 2].color = self.selectedtabcolor self.primitives[2 + (n - 1) * 3 + 2].size = iVec2(tw, self.tabsize.y * scale) - iVec2(2,-1) self.primitives[2 + (n - 1) * 3 + 3].color = self.hoveredtextcolor self.primitives[2 + (n - 1) * 3 + 1].position = iVec2(tabpos,0) self.primitives[2 + (n - 1) * 3 + 2].position = iVec2(tabpos + 1, 1) self.primitives[2 + (n - 1) * 3 + 3].position = iVec2(tabpos,0) else self.primitives[2 + (n - 1) * 3 + 1].size = iVec2(tw, self.tabsize.y * scale) self.primitives[2 + (n - 1) * 3 + 2].color = self.tabcolor self.primitives[2 + (n - 1) * 3 + 2].size = iVec2(tw, self.tabsize.y * scale) - iVec2(2,2) if n == self.hovereditem then self.primitives[2 + (n - 1) * 3 + 3].color = self.hoveredtextcolor else self.primitives[2 + (n - 1) * 3 + 3].color = self.textcolor end self.primitives[2 + (n - 1) * 3 + 1].position = iVec2(tabpos,2) self.primitives[2 + (n - 1) * 3 + 2].position = iVec2(tabpos + 1, 3) self.primitives[2 + (n - 1) * 3 + 3].position = iVec2(tabpos,2) end self.primitives[2 + (n - 1) * 3 + 3].text = self.items[n].text tabpos = tabpos + tw - 2 end end  
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