playscii/playscii/shader.py

import os.path
import platform
import time

from OpenGL import GL
from OpenGL.GL import shaders

SHADER_PATH = "shaders/"


class ShaderLord:
    # time in ms between checks for hot reload
    hot_reload_check_interval = 2 * 1000

    def __init__(self, app):
        "AWAKENS THE SHADERLORD"
        self.app = app
        self.shaders = []

    def new_shader(self, vert_source_file, frag_source_file):
        self.last_check = 0
        for shader in self.shaders:
            if (
                shader.vert_source_file == vert_source_file
                and shader.frag_source_file == frag_source_file
            ):
                # self.app.log('%s already uses same source' % shader)
                return shader
        s = Shader(self, vert_source_file, frag_source_file)
        self.shaders.append(s)
        return s

    def check_hot_reload(self):
        if (
            self.app.get_elapsed_time() - self.last_check
            < self.hot_reload_check_interval
        ):
            return
        self.last_check = self.app.get_elapsed_time()
        for shader in self.shaders:
            vert_shader_updated, frag_shader_updated = shader.has_updated()
            if vert_shader_updated:
                shader.recompile(GL.GL_VERTEX_SHADER)
            if frag_shader_updated:
                shader.recompile(GL.GL_FRAGMENT_SHADER)

    def destroy(self):
        for shader in self.shaders:
            shader.destroy()


class Shader:
    log_compile = False
    "If True, log shader compilation"
    # per-platform shader versions, declared here for easier CFG fiddling
    glsl_version_windows = 130
    glsl_version_unix = 130
    glsl_version_macos = 150
    glsl_version_es = 100

    def __init__(self, shader_lord, vert_source_file, frag_source_file):
        self.sl = shader_lord
        # vertex shader
        self.vert_source_file = vert_source_file
        self.last_vert_change = time.time()
        vert_source = self.get_shader_source(self.vert_source_file)
        if self.log_compile:
            self.sl.app.log(f"Compiling vertex shader {self.vert_source_file}...")
        self.vert_shader = self.try_compile_shader(
            vert_source, GL.GL_VERTEX_SHADER, self.vert_source_file
        )
        if self.log_compile and self.vert_shader:
            self.sl.app.log(
                f"Compiled vertex shader {self.vert_source_file} in {time.time() - self.last_vert_change:.6f} seconds"
            )
        # fragment shader
        self.frag_source_file = frag_source_file
        self.last_frag_change = time.time()
        frag_source = self.get_shader_source(self.frag_source_file)
        if self.log_compile:
            self.sl.app.log(f"Compiling fragment shader {self.frag_source_file}...")
        self.frag_shader = self.try_compile_shader(
            frag_source, GL.GL_FRAGMENT_SHADER, self.frag_source_file
        )
        if self.log_compile and self.frag_shader:
            self.sl.app.log(
                f"Compiled fragment shader {self.frag_source_file} in {time.time() - self.last_frag_change:.6f} seconds"
            )
        # shader program
        if self.vert_shader and self.frag_shader:
            self.program = shaders.compileProgram(self.vert_shader, self.frag_shader)

    def get_shader_source(self, source_file):
        src = open(SHADER_PATH + source_file, "rb").read()
        # prepend shader version for different platforms
        if self.sl.app.context_es:
            shader_version = self.glsl_version_es
        elif platform.system() == "Windows":
            shader_version = self.glsl_version_windows
        elif platform.system() == "Darwin":
            shader_version = self.glsl_version_macos
        else:
            shader_version = self.glsl_version_unix
        version_string = f"#version {shader_version}\n"
        src = bytes(version_string, "utf-8") + src
        return src

    def try_compile_shader(self, source, shader_type, source_filename):
        "Catch and print shader compilation exceptions"
        try:
            shader = shaders.compileShader(source, shader_type)
        except Exception as e:
            self.sl.app.log(f"{source_filename}: ")
            lines = e.args[0].split("\\n")
            # salvage block after "shader compile failure" enclosed in b""
            pre = lines.pop(0).split('b"')
            for line in pre + lines[:-1]:
                self.sl.app.log("  " + line)
            return
        return shader

    def has_updated(self):
        vert_mod_time = os.path.getmtime(SHADER_PATH + self.vert_source_file)
        frag_mod_time = os.path.getmtime(SHADER_PATH + self.frag_source_file)
        # return two values: vert shader changed, frag shader changed
        vert_changed = vert_mod_time > self.last_vert_change
        frag_changed = frag_mod_time > self.last_frag_change
        # store new last modified time if changed
        if vert_changed:
            self.last_vert_change = time.time()
        if frag_changed:
            self.last_frag_change = time.time()
        return vert_changed, frag_changed

    def recompile(self, shader_type):
        file_to_reload = self.vert_source_file
        if shader_type == GL.GL_FRAGMENT_SHADER:
            file_to_reload = self.frag_source_file
        new_shader_source = self.get_shader_source(file_to_reload)
        try:
            new_shader = shaders.compileShader(new_shader_source, shader_type)
            # TODO: use try_compile_shader instead here, make sure exception passes thru ok
            self.sl.app.log(f"ShaderLord: success reloading {file_to_reload}")
        except Exception:
            self.sl.app.log(f"ShaderLord: failed reloading {file_to_reload}")
            return
        # recompile program with new shader
        if shader_type == GL.GL_VERTEX_SHADER:
            self.vert_shader = new_shader
        else:
            self.frag_shader = new_shader
        self.program = shaders.compileProgram(self.vert_shader, self.frag_shader)

    def get_uniform_location(self, uniform_name):
        return GL.glGetUniformLocation(self.program, uniform_name)

    def get_attrib_location(self, attrib_name):
        return GL.glGetAttribLocation(self.program, attrib_name)

    def destroy(self):
        GL.glDeleteProgram(self.program)


class ShaderUniform:
    # MAYBE-TODO: class for remembering uniform name, type, index.
    # a Shader keeps a list of these, Renderables tell their Shader to set
    # them.  set methods use correct type and "try" to avoid crashes on
    # hot-reload when a uniform is commented out of live GLSL.
    # (try same for attributes?  more data)
    pass