Added sdf initial example. tbc

examples/samples/sdf_sapp.lua

@@ -0,0 +1,78 @@
+package.cpath   = package.cpath..";../bin/win64/?.dll"
+package.path    = package.path..";../ffi/sokol/?.lua"
+package.path    = package.path..";../?.lua"
+
+--_G.SOKOL_DLL    = "sokol_debug_dll"
+local sapp      = require("sokol_app")
+local sg        = require("sokol_gfx")
+local slib      = require("sokol_libs") -- Warn - always after gfx!!
+local hmm       = require("hmm")
+local hutils    = require("hmm_utils")
+
+local ffi = require("ffi")
+
+-- --------------------------------------------------------------------------------------
+
+ffi.cdef[[
+/* application state */
+typedef struct state {
+    sg_pass_action pass_action;
+    vs_params_t vs_params;
+    sg_pipeline pip;
+    sg_bindings* bind;
+}
+]]
+
+-- --------------------------------------------------------------------------------------
+
+local state = ffi.new("state[1]")
+local sg_range = ffi.new("sg_range[1]")
+local binding = ffi.new("sg_bindings[1]", {})
+
+local function init()
+
+    local desc = ffi.new("sg_desc[1]")
+    desc[0].environment = slib.sglue_environment()
+    desc[0].logger.func = slib.slog_func
+    sg.sg_setup( desc )
+    print("Sokol Is Valid: "..tostring(sg.sg_isvalid()))
+
+    local fsq_verts = ffi.new("float[6]", { -1.0, -3.0, 3.0, 1.0, -1.0, 1.0 })
+
+    local buffer_inf = ffi.new("sg_buffer_desc[1]")
+    buffer_inf[0].data.ptr = fsq_verts
+    buffer_inf[0].data.size = 6 * ffi.sizeof("float")
+    buffer_inf[0].label = "fsq vertices"
+
+    --// a vertex buffer to render a 'fullscreen triangle'
+    state.bind.vertex_buffers[0] = sg_make_buffer(buffer_inf)
+
+    local pipe_desc = ffi.new("sg_pipeline_desc[1]")
+    pipe_desc[0].shader = shd 
+    pipe_desc[0].layout.attrs[0].format = 2     -- vs_position float2
+    pipe_desc[0].label = "fsq-pipeline"
+
+    state[0].pip = sg.sg_make_pipeline(pipe_desc)
+
+    local pass_action = ffi.new("sg_pass_action[1]")
+    pass_action[0].colors[0].load_action = sg.SG_LOADACTION_DONTCARE
+    state[0].pass_action = pass_action[0]
+end
+
+local function frame()
+
+    local pass = ffi.new("sg_pass[1]")
+    pass[0].action = state[0].pass_action
+    pass[0].swapchain = sg.sglue_swapchain()
+    
+    sg.sg_begin_pass(pass)
+    sg.sg_apply_pipeline(state[0].pip)
+    sg.sg_apply_bindings(state[0].bind)
+    sg.sg_draw(0, 3, 1)
+    sg.sg_end_pass()
+    sg.sg_commit()
+end
+
+local function cleanup()
+    sg.sg_shutdown()
+end