kmcallister / glassful Goto Github PK

Am I doing something wrong here:

let fragment_shader_src = glassful! {
    #![version="140"]

    #[varying] static v_coord: vec3 = UNINIT;

    fn main() {
        if (abs(v_coord.z) == 0.25) {
            gl_FragColor = vec4(0., 1., 0., 1.);
        } else if (abs(v_coord.x) == 0.25) {
            gl_FragColor = vec4(0., 0., 1., 1.);
        } else if (abs(v_coord.y) == 0.25) {
            gl_FragColor = vec4(1., 0., 0., 1.);
        }
    }
};

I get:

thread '<main>' panicked at 'called `Result::unwrap()` on an `Err` value: CompilationError("0:5(8): error: syntax error, unexpected IF\n")', ../src/libcore/result.rs:731```

More ambitious version of #5.

We only support a tiny subset of Rust. It could be nice to have a 100 line grammar for shader programs instead of the grammar being the 6,000 line Rust parser + a pile of ad-hoc restrictions.

We could also make small changes to the syntax, e.g. removing the mandatory initializers on statics. As long as the tokens are compatible with Rust, the macro re-parses from source anyway.

Using the actual libsyntax parser was mostly a hack to get the proof of concept done in one day :P

rust-lang/rust#21825

The translation runs in a separate thread from rustc, in order to catch errors. So we may not be able to share libsyntax data structures. If that's the case, maybe we can hack up an acceptable codemap in the new parser context.

Perhaps using a pretty-printing library similar to Haskell's Text.PrettyPrint.

We should indent code properly, and also elide parentheses when possible (especially around assignment).

I presume each driver has its own error format, but it can't be that hard to find a line and column number.

Related to #4.

e.g.

const UNIFORMS: Uniforms;

fn vertex(v: Attributes) -> (vec4, Varyings) { ... }
fn fragment(v: Varyings) -> vec4 { ... }

where those struct definitions are lifted up from glium (c.f. #2)

which is the reference compiler for GLSL.

This will catch type errors, undefined names, as well as syntax problems the frontend won't catch.

glium already has glslang integration of some kind.

We should map errors back to the source code and print them as spans.

Modern GLSL uses in/out instead of attribute/varying, this should be supported.

So that, for example, we only declare uniforms once.

@eddyb suggested

static color: vec3 = varying;