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local gl = honey.gl
local module = {}
setmetatable(module, {__index=_G})
setfenv(1, module)
-- compile glsl source code
local function compileShader(source, type)
local shader = gl.CreateShader(type)
gl.ShaderSource(shader, source)
gl.CompileShader(shader)
return shader
end
-- helper function
local builtin = {}
local function readFile(filename)
-- support built-in shaders
if builtin[filename] then return builtin[filename] end
local f, err = io.open(filename)
if not f then error(err) end
local str = f:read("*a")
f:close()
return str
end
-- build a shader program from provided source files
local function buildProgram(sources)
local shaders = {}
-- load & compile shaders
if sources.vertex then
local shader = compileShader(readFile(sources.vertex), gl.VERTEX_SHADER)
table.insert(shaders, shader)
end
if sources.fragment then
local shader = compileShader(readFile(sources.fragment), gl.FRAGMENT_SHADER)
table.insert(shaders, shader)
end
-- link shaders
local program = gl.CreateProgram()
for _, shader in ipairs(shaders) do
gl.AttachShader(program, shader)
end
gl.LinkProgram(program)
-- clean up
for _, shader in ipairs(shaders) do
gl.DeleteShader(shader)
end
return program
end
-- public uniform setters
function setInt(program, name, value)
local location = gl.GetUniformLocation(program, name)
gl.Uniform1i(location, value)
end
function setFloat(program, name, value)
local location = gl.GetUniformLocation(program, name)
gl.Uniform1f(location, value)
end
function setVec3(program, name, value)
local location = gl.GetUniformLocation(program, name)
gl.Uniform3f(location, value[1], value[2], value[3])
end
function setVec4(program, name, value)
local location = gl.GetUniformLocation(program, name)
gl.Uniform3f(location, value[1], value[2], value[3], value[4])
end
function setMatrix(program, name, matrix)
local location = gl.GetUniformLocation(program, name)
gl.UniformMatrix4fv(location, false, matrix.data)
end
function configure(program, tbl)
local processKey = function(key, set)
local subtbl = tbl[key]
if subtbl then
for name, value in pairs(subtbl) do
set(program, name, value)
end
end
end
processKey("int", setInt)
processKey("float", setFloat)
processKey("vec3", setVec3)
processKey("vec4", setVec4)
processKey("matrix", setMatrix)
end
--===== public asset cache functions =====--
local cache = {}
-- generate id string based on shader sources
local function shaderId(sources)
return string.format(
"%s;%s",
sources.vertex or "nil",
sources.fragment or "nil"
)
end
-- get a cached shader program
get = function(sources)
local id = shaderId(sources)
if not cache[id] then
cache[id] = buildProgram(sources)
end
return cache[id]
end
-- remove a cached shader program
forget = function(sources)
local id = shaderId(sources)
if cache[id] then
gl.DeleteProgram(cache[id])
cache[id] = nil
end
end
-- clear the cache
clearCache = function()
for key, program in pairs(cache) do
gl.DeleteProgram(program)
cache[key] = nil
end
end
return module
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