lev2 glfx parser : "storage_interface"

[tweakoz]

add a new interface type to the glfx language / parser.
basically allow storage objects (SSBOS) to be in standalone interface blocks so we can share (inherit) them across multiple shaders

Say I want an SSBO layout to be shared between a compute shader and vertex shader.
eg.

/////////////////////////////////////////////

storage_interface my_storage_interface {

layout(std430, binding = 0) buffer {
int num_vertices;
mat4 mvp_L;
mat4 mvp_R;
vec3 obj_nrmz;
vec2 LW;
InputVertex inp_vertex[16384];
OutputVertex out_vertex[65536];

} ssbo_compute;

} // storage_interface my_storage_interface {

compute_interface my_compute_interface
: my_storage_interface {
inputs {
layout(local_size_x = 1, local_size_y = 1, local_size_z = 1);
}
}
vertex_interface my_vertex_interface
: my_storage_interface {
outputs {
vec2 frg_uv;
vec2 frg_age_rand;
}
}

/////////////////////////////////////////////

Also create a StorageBlock AST node so we can have improved introspective abilities for improved automation (automatic address calculation based on layout std.
Also remove GL details from grammar so we can use same storage nodes across graphics api's (OpenGL, Vulkan, Metal, etc)

[tweakoz]

Rework this a bit in light of new shader PEG parser.