Cleanup: GPU: Remove GPU_draw_primitive and default_vao_

These are not used anymore and can be replicated using the GPUBatch API.

source/blender/gpu/GPU_batch.h

@@ -154,9 +154,6 @@ void GPU_batch_draw_instanced(GPUBatch *batch, int i_count);
 /* This does not bind/unbind shader and does not call GPU_matrix_bind() */
 void GPU_batch_draw_advanced(GPUBatch *, int v_first, int v_count, int i_first, int i_count);
 
-/* Does not even need batch */
-void GPU_draw_primitive(GPUPrimType, int v_count);
-
 #if 0 /* future plans */
 
 /* Can multiple batches share a GPUVertBuf? Use ref count? */

source/blender/gpu/intern/gpu_batch.cc

@@ -280,22 +280,6 @@ void GPU_batch_draw_advanced(GPUBatch *batch, int v_first, int v_count, int i_fi
   static_cast<Batch *>(batch)->draw(v_first, v_count, i_first, i_count);
 }
 
-/* just draw some vertices and let shader place them where we want. */
-void GPU_draw_primitive(GPUPrimType prim_type, int v_count)
-{
-  GPU_context_active_get()->state_manager->apply_state();
-
-  /* we cannot draw without vao ... annoying ... */
-  glBindVertexArray(GPU_vao_default());
-
-  GLenum type = blender::gpu::to_gl(prim_type);
-  glDrawArrays(type, 0, v_count);
-
-  /* Performance hog if you are drawing with the same vao multiple time.
-   * Only activate for debugging.*/
-  // glBindVertexArray(0);
-}
-
 /** \} */
 
 /* -------------------------------------------------------------------- */

source/blender/gpu/intern/gpu_context.cc

@@ -126,12 +126,6 @@ GPUContext *GPU_context_active_get(void)
   return active_ctx;
 }
 
-GLuint GPU_vao_default(void)
-{
-  BLI_assert(active_ctx); /* need at least an active context */
-  return static_cast<GLContext *>(active_ctx)->default_vao_;
-}
-
 GLuint GPU_vao_alloc(void)
 {
   GLuint new_vao_id = 0;

source/blender/gpu/intern/gpu_context_private.hh

@@ -82,8 +82,6 @@ struct GPUContext {
   MEM_CXX_CLASS_ALLOC_FUNCS("GPUContext")
 };
 
-GLuint GPU_vao_default(void);
-
 /* These require a gl ctx bound. */
 GLuint GPU_buf_alloc(void);
 GLuint GPU_tex_alloc(void);

source/blender/gpu/opengl/gl_context.cc

@@ -47,8 +47,6 @@ using namespace blender::gpu;
 GLContext::GLContext(void *ghost_window, GLSharedOrphanLists &shared_orphan_list)
     : shared_orphan_list_(shared_orphan_list)
 {
-  glGenVertexArrays(1, &default_vao_);
-
   float data[4] = {0.0f, 0.0f, 0.0f, 1.0f};
   glGenBuffers(1, &default_attr_vbo_);
   glBindBuffer(GL_ARRAY_BUFFER, default_attr_vbo_);
@@ -101,7 +99,6 @@ GLContext::~GLContext()
   for (GLVaoCache *cache : vao_caches_) {
     cache->clear();
   }
-  glDeleteVertexArrays(1, &default_vao_);
   glDeleteBuffers(1, &default_attr_vbo_);
 }
 

source/blender/gpu/opengl/gl_context.hh

@@ -61,8 +61,6 @@ class GLSharedOrphanLists {
 class GLContext : public GPUContext {
   /* TODO(fclem) these needs to become private. */
  public:
-  /** Default VAO for procedural draw calls. */
-  GLuint default_vao_;
   /** VBO for missing vertex attrib binding. Avoid undefined behavior on some implementation. */
   GLuint default_attr_vbo_;
   /**