Modern graphics APIs have immutable objects, with mutable data. For example,
a texture's dimensions are immutable, while the texture contents is not.
Change the GPU API abstraction to match.
Clearing a Texture is convenient to do with a plain []byte. Generalize
Texture.Upload to take a plain byte slice and introduce a helper function for
uploading *image.RGBA data.
Add TextureFormatRGBA8 a format for the linear RGB colorspace.
Add OpenGL ES 3.1 functions for compute programs.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Use greater-than-or-equal test and saturate the z depth buffer
when more than 65k objects are drawn.
Fixes gio#127
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Specifying the clear color and depth at the time of clearing is
less error prone and a better for modern GPU APIs. As a bonus, we
can get rid of the BufferAttachment type.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
OpenGL supports casting from int to float during vertex array
reading. Direct3D doesn't. Since we're transpiling from GLSL, we can't
directly use the Direct3D builtin "asint". So that leaves using
"ivec2" instead of vec2.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur