[WIP] Shadertoy and shader plot types

[SimonDanisch]

adds:

shadertoy(rect2d, frag_shader)

To run shadertoy shaders like this:

TODOs:

• map arbitrary uniforms to shader (using ShaderAbstractions)
• allow geometry and vertex shader (using a new plot type)
• clean up and docs

[MakieBot]

Compile Times benchmark

Note, that these numbers may fluctuate on the CI servers, so take them with a grain of salt. All benchmark results are based on the mean time and negative percent mean faster than the base branch. Note, that GLMakie + WGLMakie run on an emulated GPU, so the runtime benchmark is much slower. Results are from running:

using_time = @ctime using Backend
# Compile time
create_time = @ctime fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @ctime Makie.colorbuffer(display(fig))
# Runtime
create_time = @benchmark fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @benchmark Makie.colorbuffer(fig)

	using	create	display	create	display
GLMakie	6.37s (6.29, 6.45) 0.06+-	162.49ms (160.12, 167.03) 2.40+-	472.46ms (468.66, 479.51) 3.94+-	8.26ms (8.19, 8.35) 0.06+-	26.29ms (25.99, 26.62) 0.19+-
master	6.39s (6.30, 6.49) 0.06+-	168.35ms (160.56, 182.78) 7.44+-	480.73ms (467.00, 511.27) 14.71+-	8.21ms (8.11, 8.31) 0.07+-	26.22ms (25.80, 26.63) 0.27+-
evaluation	1.00x invariant, -0.01s (-0.19d, 0.72p, 0.06std)	1.04x invariant, -5.85ms (-1.06d, 0.09p, 4.92std)	1.02x invariant, -8.27ms (-0.77d, 0.19p, 9.32std)	0.99x invariant, 0.06ms (0.89d, 0.12p, 0.06std)	1.00x invariant, 0.07ms (0.28d, 0.61p, 0.23std)
CairoMakie	6.15s (6.07, 6.19) 0.06+-	168.12ms (162.97, 181.00) 6.49+-	205.73ms (196.45, 222.33) 9.47+-	8.07ms (7.88, 8.35) 0.18+-	1.21ms (1.20, 1.23) 0.01+-
master	6.11s (5.98, 6.31) 0.10+-	163.37ms (159.93, 168.28) 2.68+-	199.33ms (196.53, 201.57) 1.91+-	7.98ms (7.86, 8.12) 0.10+-	1.22ms (1.21, 1.24) 0.01+-
evaluation	0.99x invariant, 0.04s (0.55d, 0.33p, 0.08std)	0.97x invariant, 4.75ms (0.96d, 0.11p, 4.58std)	0.97x invariant, 6.41ms (0.94d, 0.13p, 5.69std)	0.99x invariant, 0.09ms (0.62d, 0.27p, 0.14std)	1.01x invariant, -0.01ms (-0.72d, 0.20p, 0.01std)
WGLMakie	6.74s (6.70, 6.77) 0.03+-	168.60ms (164.71, 176.39) 5.09+-	5.72s (5.66, 5.87) 0.08+-	13.17ms (12.42, 15.51) 1.06+-	134.36ms (127.13, 140.59) 5.27+-
master	6.78s (6.71, 6.90) 0.06+-	170.10ms (165.54, 176.37) 3.30+-	5.98s (5.95, 6.03) 0.03+-	12.69ms (12.42, 12.81) 0.14+-	134.09ms (129.01, 138.08) 3.27+-
evaluation	1.01x invariant, -0.04s (-0.82d, 0.16p, 0.05std)	1.01x invariant, -1.5ms (-0.35d, 0.53p, 4.19std)	1.04x faster ✓, -0.25s (-4.11d, 0.00p, 0.05std)	0.96x invariant, 0.48ms (0.64d, 0.28p, 0.60std)	1.00x invariant, 0.26ms (0.06d, 0.91p, 4.27std)