Hello and welcome to the development thread of the gscept game engine and pipeline suite. Seeing as there is no point in stalling, I’m going to explain exactly what we are currently doing.
The core of the engine relies on the Nebula Device, developed by a company previously known as RadonLabs. They’ve developed a, cross-platform and highly maintainable game engine, which supports DirectX 9, job dispatching and content-management using a Maya plugin. The problem is that we here in Skellefteå, have a pre-release of the engine, which basically means that we don’t have any of the cool pipeline tools. So, about 3 months ago, we started making our own pipeline for the engine, and one of these tools is Nody.
Nody is a graphical shader designer. It lets you create nodes of five different types, vertex, subdivision, displacement, geometry and effect nodes. Each node type corresponds to a segment in the rendering pipeline. The idea is to be able to combine different nodes together in order to graphically generate a pipeline pass. Nody is also equipped with two subtools, the frame shader editor, and the material editor. The frame shader editor works as a tool to modify a frame shader, or render path.
The tool has functionality to add render targets, multiple render targets, and frame passes. A frame pass corresponds to a set of shaders, which consists of a vertex shader, a pixel shader, and optional hull shader, domain shader and geometry shader. A frame pass can be used to either render a dynamic model, be it skinned or static, a full-screen quad for post effects, and four specialized for text, GUI, simple shapes and lights. The point with having specialized frame passes is to be able to script passes that needs special treatment. Nebula renders lights using deferred lighting, so all the lights are rendered in a three passes, one for the global light, one for the spot lights and one for the point lights. The lights pass handled this very special pass by denoting it with a lights pass node, so you don’t need to attach a material (I will explain materials later) to every single light for them to render. A simple frame in Nebula renders normals and depth to a GBuffer, renders the lights using the GBuffer, and then renders a model, using the light buffer as the light values.
Previously, Nebula relied on the effect system developed by Microsoft for DirectX, which allows you to basically setup entire render passes using a single file. The effects system allows you to set depth-stencil states, blend states and rasterizer states, as well as which shader goes where in the pass. The bad thing about effects is that Microsoft seem to be slowly moving away from it, and OpenGL doesn’t offer such a feature. Why would I even care about OpenGL? Well, this is how I see it, better make it as general as possible while I’m already in the process of remaking it, rather than keeping to an old library which is strongly discouraged to use because it’s not a part of the standard SDK.
The way Nebula rendered before was using effects and annotations, which is basically yet another way to script what technique should be used when rendering an object. It start the normal-depth pass, and then set the annotations correctly for different objects. So it would render all static objects, and set the annotation to use normal-depth to render to the GBuffer, and then in a later pass, use the exact same batching, but just change the annotation to be used for the current pass. And seeing as we won’t be using effects no more, this will become a huge problem. Enter materials.
Materials are what you attach to an object in order to make it render. The frame shader denotes when a pass should take place, but the material denotes in what pass the object should be rendered. This way, an object can actually have several shaders, like normal-depth, shadow and color. Nody supplies an editor for this as well.
This picture show Nody in its current state.
It shows you a preview to the right (not yet implemented) as well as the main window, together with the frame shader tool and material editor. The material editor and frame shader are two detachable windows.
Currently, I’m working on making the displacement nodes to work in a render. As you might have guessed, the subdivision nodes are used to build a hull shader, and the displacement nodes are used to build a domain shader, both of which are new features in DirectX 11. So yeah, Nebula has been rewritten to not only use ordinary shaders instead of effects, but it’s also been upgraded to support DirectX 11. The funny thing is that my work computer shows a blank screen when rendering, but my home computer halts the driver, just to let me know I’m doing something wrong. Isn’t that so nice!?
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