Source/EEVEE & Viewport/GPU Module/GPUViewport
The GPUViewport (
gpu/intern/gpu_viewport.c) contains the render buffers, framebuffer and engine data for an editor. Editors that make use of it are the 3D Viewport and the UV/Image editor. Other editors use offscreens.
Any draw engine can store data in the 3d viewport. This data is organized in 4 lists:
- Other data
Engine can store data here as a cache specific for the editor. It is also used for TAA where the draw engine continues where it stopped the previous redraw. Workbench and EEVEE make use of this.
GPUViewport has a depth- and 2 color-textures. The main color texture (
DefaultTextureList.color) is used for drawing in Linear Scene Reference Space. It is used by the render and draw engines (Cycles, EEVEE, Workbench or any external engine) to draw the scene. The second color texture (
DefaultTextureList.color_overlay) is the overlay texture. This texture is in linear display space. The color overlay texture is encoded in SRGB to save GPU memory. These textures can be retrieved by calling
GPU_viewport_texture_list_get. There are also some predefined framebuffers that can be used. The framebuffers can be retrieved by calling
GPU_viewport_framebuffer_list_get. There is a shared depthbuffer that is used by both color textures.
When drawing the GPUViewport to the display the textures are combined and transformed to display space. For this the default texture is transferred to display space (in rendered mode the view transform is also applied). The overlay texture is transferred (linear to non-linear) to match the display space.
This process is normally hidden for the development as it is triggered by
WM_draw.c#wm_draw_region_blit, which calls
GPU_viewport_draw_to_screen. The actual drawing is done in
gpu_viewport_draw_colormanaged. Inside the draw manager the function
drw_viewport_colormanagement_set determines the color spaces and related configuration. The fragment shader that does the conversion is
gpu_shader_display_transform which is located in