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Vulkan-based tetrachromacy display engine.

Engine Architecture

Frontend

Frontend is still under construction! Currently all renders are hard-coded in backend.

Backend

Engine backend consists of core logic on vulkan rendering, presentation, and even-odd frame synchronization.

"Deferred" Presentation

The engine holds two off-screen frame buffers, each responsible for one color space(RGB/OCV)

Each tick, the engine simultaneously renders to the two buffers with RGB and OCV logic.

Once the rendering is done, depending on the presentation mode:

• TetraMode::kDualProjector: both buffers are committed to either RGB or OCV projector.
• TetraMode::kEvenOddSoftwareSync or TetraMode::kEvenOddHardwareSync: the engine determines the count of the vertical blanking period, either through hardware APIs or a virtual software frame counter; the engine then commits one frame buffer while discarding the other.

Even-Odd Frame Synchronization

To determine even/odd-ness of the frame to present, the engine relies on the total number of vertical blanking periods % 2. This information is obtained using vkGetSwapchainCounterEXT, when the engine runs under kEvenOddSoftwareSync. For kEvenOddSoftwareSync, vkGetPastPresentationTimingGOOGLE is used to provide a rought estimation.

ImGui

Given most of tetrachromacy test are performed under 2D space, the engine provides an interface with DearImGui that allows for easy integration and development of 2D RGV&OCV apps.

In engine backend Tetrium::drawImGui(ColorSpace) function calls into various ImGui render widgets. Internally, drawImGui operates on both RGB and OCV color space, one can differentiate them using the colorSpace argument and develop various widgets. As an example:

enum ColorSpace {
    RGB,
    OCV
};
drawImGui(ColorSpace colorSpace) {
    switch colorSpace {
        case RGB:
            ImGui::Image(ishiHaraImgRGB);
            break;
        case OCV:
            ImGui::Image(ishiHaraImgOCV);
            break;
    }
}

Requirements

All Systems

• CMake
• Vulkan SDK
• make or ninja

Hardware Even-odd frame sync

• NVIDIA GPU supporting VK_EXT_display_surface_counter

Build

Apple

set VULKAN_LIB_PATH and MOLTENVK_LIB_PATH in CMakeLists.txt to your own path after installing Vulkan SDK

FreeType

brew install freetype

validate that /opt/homebrew/include/freetype2 and /opt/homebrew/lib/libfreetype.dylib contains freetype library and include files.

Linux

install X11 and Xrandr for direct display access, for hardware even-odd frame sync

install freetype

sudo apt-get install libfreetype6-dev

Windows

tbd...

Run

Config loading is not supported yet. To configure run option, modify Tetrium::InitOptions options field to set display mode.

References

Theory of Human Tetrachromatic Color Experience and Printing

TetraPolyscope