shader
User fragment shaders.
newShader takes Metal Shading Language source for a fragment function named
"frag", which replaces the built-in fragment stage while the shader is set.
A standard preamble (the metal header and the VSOutput struct the built-in
vertex shader produces) is prepended for you, so the source you pass is just
the fragment function. It takes the vertex output through stage_in, a texture
and sampler at slot 0, and, when you ask for a uniform, a fragment uniform
buffer at slot 0. The exact signature is in the Shaders section of the docs
and in the shader example.
Inside the function, in.uv and in.color come from the vertex, in.position.xy
is the pixel position, tex is the current texture (a white pixel when drawing
shapes), and the uniform is filled by send.
MSL source runs on the Metal backend only. To write a shader that runs
everywhere, author it in GLSL, compile it offline to SPIR-V and MSL the same
way the built-in shaders are (see the shaders Makefile), and pass both blobs
to the second newShader below, which picks the one the backend wants.
newShader ¶
proc newShader(nim2d: Nim2d; fragmentSrc: string; uniformFloats = 0): Shader
Compile a fragment shader from MSL source (entry "frag"); runs on Metal.
uniformFloats is how many float32 the fragment uniform holds (0 for none);
fill it later with send.
Parameters
-
nim2d(Nim2d) -
fragmentSrc(string) -
uniformFloats(auto)
Returns
Shader
newShader ¶
proc newShader(nim2d: Nim2d; spirv, msl: string; uniformFloats = 0): Shader
Compile a fragment shader from precompiled cross-platform blobs: SPIR-V for
Vulkan, MSL for Metal, both produced offline from one GLSL source. The blob
matching the live backend is used, so this runs on macOS, iOS, Linux and
Windows. The GLSL takes vUV at location 0 and vColor at location 1 from
the vertex, a sampler in set 2, and (if used) a uniform buffer in set 3.
Parameters
-
nim2d(Nim2d) -
spirv(string) -
msl(string) -
uniformFloats(auto)
Returns
Shader
send ¶
proc send(shader: Shader; values: openArray[float32])
Fill the fragment uniform buffer with float32 values.
Parameters
-
shader(Shader) -
values(openArray[float32])
setShader ¶
proc setShader(nim2d: Nim2d; shader: Shader)
Draw with this shader until it is unset.
Parameters
-
nim2d(Nim2d) -
shader(Shader)
setShader ¶
proc setShader(nim2d: Nim2d)