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local gl = honey.gl
local module = {}
setmetatable(module, {__index=_G})
setfenv(1, module)
-- append the 8 floats per vertex to the vertices table
local function insertVertex(vertices, attrib, vertex)
local pos = 3*vertex.v_idx
for i=1,3 do
table.insert(vertices, attrib.vertices[pos+i])
end
local normal = 3*vertex.vn_idx
for i=1,3 do
table.insert(vertices, attrib.normals[normal+i])
end
local tex = 2*vertex.vt_idx
for i=1,2 do
table.insert(vertices, attrib.texcoords[tex+i])
end
end
-- creates a table of floats representing vertex data
-- and a table of ints representing face indices within the vertices
local function loadShape(shape, attrib, debug)
local vertices = {}
local indices = {}
local start = shape.face_offset
local finish = start + shape.length
for i=start,finish-1 do
assert(attrib.face_num_verts[i+1] == 3, "non-triangular face!")
for j=0,2 do
local vertex = attrib.faces[(3*i) + j + 1]
insertVertex(vertices, attrib, vertex, debug)
table.insert(indices, #indices)
end
end
return vertices, indices
end
-- public helper function (used in some other places, like trimesh construction)
-- packages the vertices & indices tables from loadShape into a single array
loadFile = function(filename)
local flags = honey.tinyobj.FLAG_TRIANGULATE
local attrib, shapes, materials = honey.tinyobj.parse_obj(filename, flags)
local meshes = {}
for _, shape in ipairs(shapes) do
local vertices, indices = loadShape(shape, attrib, debug)
table.insert(meshes, {vertices=vertices, indices=indices})
end
return meshes
end
-- helper function to create a gl vertex array object from (vertices, indices) pair
local function createMesh(vertices, indices)
vao = gl.GenVertexArrays()
vbo = gl.GenBuffers()
ebo = gl.GenBuffers()
gl.BindVertexArray(vao)
gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
gl.BufferData(gl.ARRAY_BUFFER, gl.FLOAT, vertices, gl.STATIC_DRAW)
gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebo)
gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, gl.UNSIGNED_INT, indices, gl.STATIC_DRAW)
local stride = 8
local offset = 0
-- position
gl.VertexAttribPointer(0, 3, false, stride, offset)
gl.EnableVertexAttribArray(0)
offset = offset+3
-- normal
gl.VertexAttribPointer(1, 3, false, stride, offset)
gl.EnableVertexAttribArray(1)
offset = offset+3
-- texture
gl.VertexAttribPointer(2, 2, false, stride, offset)
gl.EnableVertexAttribArray(2)
offset = offset+2
return vao, vbo, ebo, #vertices
end
local cache = {}
-- get a gl vertex array object + vertex count
get = function(filename, index)
if not cache[filename] then
local c = {}
local meshes = loadFile(filename)
for _, m in ipairs(meshes) do
local vao, vbo, ebo, count = createMesh(m.vertices, m.indices)
table.insert(c, { vao=vao, vbo=vbo, ebo=ebo, count=count })
end
cache[filename] = c
end
local m = cache[filename][index]
return m.vao, m.count
end
-- forget a mesh
forget = function(filename)
if not cache[filename] then return end
for _, m in ipairs(cache[filename]) do
gl.DeleteBuffers(m.vbo)
gl.DeleteBuffers(m.ebo)
gl.DeleteVertexArrays(m.vao)
end
cache[filename] = nil
end
-- clear the cache
clearCache = function()
for key in pairs(cache) do
forget(key)
end
end
--===== builtin meshes =====--
local function builtin(name, vertices, indices)
local vao, vbo, ebo, count = createMesh(vertices, indices)
cache[name] = { {vao=vao, vbo=vbo, ebo=ebo, count=count } }
end
init = function()
builtin(
"builtin.quad",
{ 0, 0, 0, 0, 1, 0, 0, 0,
1, 0, 0, 0, 1, 0, 1, 0,
0, 1, 0, 0, 1, 0, 0, 1,
1, 1, 0, 0, 1, 0, 1, 1 },
{ 0, 1, 3, 0, 3, 2 }
)
end
return module
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