1 files changed, 143 insertions, 0 deletions
diff --git a/honey/asset/shader.lua b/honey/asset/shader.lua
new file mode 100644
index 0000000..0e8c93a
--- /dev/null
+++ b/honey/asset/shader.lua
@@ -0,0 +1,143 @@
+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.vertex then
+		local shader = compileShader(readFile(sources.vertex), gl.VERTEX_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