Context

The context object represents the purest, most directly accessible, abilities of the device’s 3D rendering pipeline.

Methods

CSO State

All CSO state is created, bound, and destroyed, with triplets of methods that all follow a specific naming scheme. For example, create_blend_state, bind_blend_state, and destroy_blend_state.

CSO objects handled by the context object:

• Blend: *_blend_state
• Sampler: These are special; they can be bound to either vertex or fragment samplers, and they are bound in groups. bind_fragment_sampler_states, bind_vertex_sampler_states
• Rasterizer: *_rasterizer_state
• Depth, Stencil, & Alpha: *_depth_stencil_alpha_state
• Shader: These have two sets of methods. *_fs_state is for fragment shaders, and *_vs_state is for vertex shaders.

Resource Binding State

This state describes how resources in various flavours (textures, buffers, surfaces) are bound to the driver.

• set_constant_buffer
• set_framebuffer_state
• set_fragment_sampler_textures
• set_vertex_sampler_textures
• set_vertex_buffers

Non-CSO State

These pieces of state are too small, variable, and/or trivial to have CSO objects. They all follow simple, one-method binding calls, e.g. set_edgeflags.

• set_edgeflags
• set_blend_color
• set_clip_state
• set_polygon_stipple
• set_scissor_state
• set_viewport_state
• set_vertex_elements

Clearing

clear initializes some or all of the surfaces currently bound to the framebuffer to particular RGBA, depth, or stencil values.

Clear is one of the most difficult concepts to nail down to a single interface and it seems likely that we will want to add additional clear paths, for instance clearing surfaces not bound to the framebuffer, or read-modify-write clears such as depth-only or stencil-only clears of packed depth-stencil buffers.

Drawing

draw_arrays

draw_elements

draw_range_elements

Queries

Queries gather some statistic from the 3D pipeline over one or more draws. Queries may be nested, though no state tracker currently exercises this.

Queries can be created with create_query and deleted with destroy_query. To enable a query, use begin_query, and when finished, use end_query to stop the query. Finally, get_query_result is used to retrieve the results.

Flushing

flush

Resource Busy Queries

is_texture_referenced

is_buffer_referenced

Blitting

These methods emulate classic blitter controls. They are not guaranteed to be available; if they are set to NULL, then they are not present.

These methods operate directly on pipe_surface objects, and stand apart from any 3D state in the context. Blitting functionality may be moved to a separate abstraction at some point in the future.

surface_fill performs a fill operation on a section of a surface.

surface_copy blits a region of a surface to a region of another surface, provided that both surfaces are the same format. The source and destination may be the same surface, and overlapping blits are permitted.

The interfaces to these calls are likely to change to make it easier for a driver to batch multiple blits with the same source and destination.