Building igl statically and moving to the dep scripts

Fixing dep build script on Windows and removing some warnings.

Use bundled igl by default.

Not building with the dependency scripts if not explicitly stated. This way, it will stay in
Fix the libigl patch to include C source files in header only mode.

src/libigl/igl/opengl/init_render_to_texture.cpp

@@ -0,0 +1,86 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+//
+// Copyright (C) 2015 Alec Jacobson <alecjacobson@gmail.com>
+//
+// This Source Code Form is subject to the terms of the Mozilla Public License
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can
+// obtain one at http://mozilla.org/MPL/2.0/.
+#include "init_render_to_texture.h"
+#include "gl.h"
+#include <cassert>
+
+IGL_INLINE void igl::opengl::init_render_to_texture(
+  const size_t width,
+  const size_t height,
+  const bool depth_texture,
+  GLuint & tex_id,
+  GLuint & fbo_id,
+  GLuint & d_id)
+{
+  using namespace std;
+  // http://www.opengl.org/wiki/Framebuffer_Object_Examples#Quick_example.2C_render_to_texture_.282D.29
+  const auto & gen_tex = [](GLuint & tex_id)
+  {
+    glGenTextures(1, &tex_id);
+    glBindTexture(GL_TEXTURE_2D, tex_id);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  };
+  gen_tex(tex_id);
+  //NULL means reserve texture memory, but texels are undefined
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, width, height, 0, GL_BGRA, GL_FLOAT, NULL);
+  glBindTexture(GL_TEXTURE_2D, 0);
+
+  glGenFramebuffers(1, &fbo_id);
+  glBindFramebuffer(GL_FRAMEBUFFER, fbo_id);
+  //Attach 2D texture to this FBO
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex_id, 0);
+  if(depth_texture)
+  {
+    // Generate a depth texture
+    gen_tex(d_id);
+    glTexImage2D(
+      GL_TEXTURE_2D,
+      0,
+      GL_DEPTH_COMPONENT32,
+      width,
+      height,
+      0,
+      GL_DEPTH_COMPONENT,
+      GL_FLOAT,
+      NULL);
+    glFramebufferTexture2D(
+      GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,GL_TEXTURE_2D,d_id,0);
+  }else
+  {
+    // Attach a depth buffer
+    glGenRenderbuffers(1, &d_id);
+    glBindRenderbuffer(GL_RENDERBUFFER, d_id);
+    glRenderbufferStorage(GL_RENDERBUFFER,GL_DEPTH_COMPONENT24,width,height);
+    glFramebufferRenderbuffer(
+      GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,GL_RENDERBUFFER,d_id);
+  }
+
+  //Does the GPU support current FBO configuration?
+  GLenum status;
+  status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+  assert(status == GL_FRAMEBUFFER_COMPLETE);
+  // Unbind to clean up
+  if(!depth_texture)
+  {
+    glBindRenderbuffer(GL_RENDERBUFFER, 0);
+  }
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+}
+
+IGL_INLINE void igl::opengl::init_render_to_texture(
+  const size_t width,
+  const size_t height,
+  GLuint & tex_id,
+  GLuint & fbo_id,
+  GLuint & dfbo_id)
+{
+  return init_render_to_texture(width,height,false,tex_id,fbo_id,dfbo_id);
+}