gpu/internal/opengl,app/internal/wm: generalize desktop OpenGL support

This changes moves the macOS specific setup for desktop OpenGL to the
portable opengl package. The opengl package already takes care of the
desktop OpenGL setup for sRGB framebuffers, and by moving the code we
avoid calling the wrong OpenGL functions in case both OpenGL.framework
and ANGLE libGLESv2.dylib is linked into the program.

Remove the interface casting expressions for gl.Functions; it wasn't
worth the trouble to keep updated.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

internal/gl/gl.go

@@ -101,84 +101,3 @@ const (
 	TIME_ELAPSED_EXT = 0x88BF
 	GPU_DISJOINT_EXT = 0x8FBB
 )
-
-var _ interface {
-	ActiveTexture(texture Enum)
-	AttachShader(p Program, s Shader)
-	BeginQuery(target Enum, query Query)
-	BindAttribLocation(p Program, a Attrib, name string)
-	BindBuffer(target Enum, b Buffer)
-	BindBufferBase(target Enum, index int, buffer Buffer)
-	BindFramebuffer(target Enum, fb Framebuffer)
-	BindImageTexture(unit int, t Texture, level int, layered bool, layer int, access, format Enum)
-	BindRenderbuffer(target Enum, fb Renderbuffer)
-	BindTexture(target Enum, t Texture)
-	BlendEquation(mode Enum)
-	BlendFunc(sfactor, dfactor Enum)
-	BlitFramebuffer(sx0, sy0, sx1, sy1, dx0, dy0, dx1, dy1 int, mask Enum, filter Enum)
-	BufferData(target Enum, size int, usage Enum)
-	BufferSubData(target Enum, offset int, src []byte)
-	CheckFramebufferStatus(target Enum) Enum
-	Clear(mask Enum)
-	ClearColor(red, green, blue, alpha float32)
-	ClearDepthf(d float32)
-	CompileShader(s Shader)
-	CreateBuffer() Buffer
-	CreateFramebuffer() Framebuffer
-	CreateProgram() Program
-	CreateQuery() Query
-	CreateRenderbuffer() Renderbuffer
-	CreateShader(ty Enum) Shader
-	CreateTexture() Texture
-	DeleteBuffer(v Buffer)
-	DeleteFramebuffer(v Framebuffer)
-	DeleteProgram(p Program)
-	DeleteQuery(query Query)
-	DeleteRenderbuffer(r Renderbuffer)
-	DeleteShader(s Shader)
-	DeleteTexture(v Texture)
-	DepthFunc(f Enum)
-	DepthMask(mask bool)
-	DisableVertexAttribArray(a Attrib)
-	Disable(cap Enum)
-	DispatchCompute(x, y, z int)
-	DrawArrays(mode Enum, first, count int)
-	DrawElements(mode Enum, count int, ty Enum, offset int)
-	Enable(cap Enum)
-	EnableVertexAttribArray(a Attrib)
-	EndQuery(target Enum)
-	FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level int)
-	FramebufferRenderbuffer(target, attachment, renderbuffertarget Enum, renderbuffer Renderbuffer)
-	GetBinding(pname Enum) Object
-	GetError() Enum
-	GetInteger(pname Enum) int
-	GetProgrami(p Program, pname Enum) int
-	GetProgramInfoLog(p Program) string
-	GetQueryObjectuiv(query Query, pname Enum) uint
-	GetShaderi(s Shader, pname Enum) int
-	GetShaderInfoLog(s Shader) string
-	GetString(pname Enum) string
-	GetUniformBlockIndex(p Program, name string) uint
-	GetUniformLocation(p Program, name string) Uniform
-	InvalidateFramebuffer(target, attachment Enum)
-	LinkProgram(p Program)
-	MapBufferRange(target Enum, offset, length int, access Enum) []byte
-	MemoryBarrier(barriers Enum)
-	ReadPixels(x, y, width, height int, format, ty Enum, data []byte)
-	RenderbufferStorage(target, internalformat Enum, width, height int)
-	ShaderSource(s Shader, src string)
-	TexImage2D(target Enum, level int, internalFormat Enum, width, height int, format, ty Enum)
-	TexParameteri(target, pname Enum, param int)
-	TexStorage2D(target Enum, levels int, internalFormat Enum, width, height int)
-	TexSubImage2D(target Enum, level, xoff, yoff int, width, height int, format, ty Enum, data []byte)
-	UniformBlockBinding(p Program, uniformBlockIndex uint, uniformBlockBinding uint)
-	Uniform1f(dst Uniform, v float32)
-	Uniform1i(dst Uniform, v int)
-	Uniform2f(dst Uniform, v0, v1 float32)
-	Uniform3f(dst Uniform, v0, v1, v2 float32)
-	Uniform4f(dst Uniform, v0, v1, v2, v3 float32)
-	UseProgram(p Program)
-	UnmapBuffer(target Enum) bool
-	VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride, offset int)
-	Viewport(x, y, width, height int)
-} = (*Functions)(nil)