diff --git a/intern/glew-mx/intern/gl-deprecated.h b/intern/glew-mx/intern/gl-deprecated.h
index b6524cd5197..d101591fea3 100644
--- a/intern/glew-mx/intern/gl-deprecated.h
+++ b/intern/glew-mx/intern/gl-deprecated.h
@@ -824,10 +824,12 @@
 #define GL_SOURCE0_ALPHA DO_NOT_USE_GL_SOURCE0_ALPHA
 #undef GL_SOURCE0_RGB
 #define GL_SOURCE0_RGB DO_NOT_USE_GL_SOURCE0_RGB
-#undef GL_SOURCE1_ALPHA
-#define GL_SOURCE1_ALPHA DO_NOT_USE_GL_SOURCE1_ALPHA
-#undef GL_SOURCE1_RGB
-#define GL_SOURCE1_RGB DO_NOT_USE_GL_SOURCE1_RGB
+#if 0 /* Those are reused as new valid enum! GL_SRC1_COLOR etc... */
+#  undef GL_SOURCE1_ALPHA
+#  define GL_SOURCE1_ALPHA DO_NOT_USE_GL_SOURCE1_ALPHA
+#  undef GL_SOURCE1_RGB
+#  define GL_SOURCE1_RGB DO_NOT_USE_GL_SOURCE1_RGB
+#endif
 #undef GL_SOURCE2_ALPHA
 #define GL_SOURCE2_ALPHA DO_NOT_USE_GL_SOURCE2_ALPHA
 #undef GL_SOURCE2_RGB
diff --git a/source/blender/gpu/intern/gpu_context.cc b/source/blender/gpu/intern/gpu_context.cc
index da12a58ba87..ef02ec24a00 100644
--- a/source/blender/gpu/intern/gpu_context.cc
+++ b/source/blender/gpu/intern/gpu_context.cc
@@ -70,7 +70,7 @@ GPUContext::GPUContext()
 GPUContext::~GPUContext()
 {
   GPU_matrix_state_discard(matrix_state);
-  delete state_stack;
+  delete state_manager;
 }
 
 bool GPUContext::is_active_on_thread(void)
diff --git a/source/blender/gpu/intern/gpu_context_private.hh b/source/blender/gpu/intern/gpu_context_private.hh
index 04785187e8b..b774d6b0995 100644
--- a/source/blender/gpu/intern/gpu_context_private.hh
+++ b/source/blender/gpu/intern/gpu_context_private.hh
@@ -46,7 +46,7 @@ struct GPUContext {
   GPUShader *shader = NULL;
   GPUFrameBuffer *current_fbo = NULL;
   GPUMatrixState *matrix_state = NULL;
-  blender::gpu::GPUStateStack *state_stack = NULL;
+  blender::gpu::GPUStateManager *state_manager = NULL;
 
  protected:
   /** Thread on which this context is active. */
diff --git a/source/blender/gpu/intern/gpu_state.cc b/source/blender/gpu/intern/gpu_state.cc
index 8a9724e967f..bd581f06462 100644
--- a/source/blender/gpu/intern/gpu_state.cc
+++ b/source/blender/gpu/intern/gpu_state.cc
@@ -38,15 +38,12 @@
 
 #include "gpu_state_private.hh"
 
-/* TODO remove */
-#include "gl_state.hh"
-
 using namespace blender::gpu;
 
 #define SET_STATE(_prefix, _state, _value) \
   do { \
-    GPUStateStack *stack = GPU_context_active_get()->state_stack; \
-    auto &state_object = stack->_prefix##stack_top_get(); \
+    GPUStateManager *stack = GPU_context_active_get()->state_manager; \
+    auto &state_object = stack->_prefix##state; \
     state_object._state = _value; \
     /* TODO remove this and only push state at draw time. */ \
     stack->set_##_prefix##state(state_object); \
@@ -107,8 +104,8 @@ void GPU_write_mask(eGPUWriteMask mask)
 
 void GPU_color_mask(bool r, bool g, bool b, bool a)
 {
-  GPUStateStack *stack = GPU_context_active_get()->state_stack;
-  auto &state = stack->stack_top_get();
+  GPUStateManager *stack = GPU_context_active_get()->state_manager;
+  auto &state = stack->state;
   eGPUWriteMask write_mask = state.write_mask;
   SET_FLAG_FROM_TEST(write_mask, r, GPU_WRITE_RED);
   SET_FLAG_FROM_TEST(write_mask, g, GPU_WRITE_GREEN);
@@ -121,8 +118,8 @@ void GPU_color_mask(bool r, bool g, bool b, bool a)
 
 void GPU_depth_mask(bool depth)
 {
-  GPUStateStack *stack = GPU_context_active_get()->state_stack;
-  auto &state = stack->stack_top_get();
+  GPUStateManager *stack = GPU_context_active_get()->state_manager;
+  auto &state = stack->state;
   eGPUWriteMask write_mask = state.write_mask;
   SET_FLAG_FROM_TEST(write_mask, depth, GPU_WRITE_DEPTH);
   state.write_mask = write_mask;
@@ -143,8 +140,8 @@ void GPU_clip_distances(int distances_enabled)
 
 void GPU_depth_range(float near, float far)
 {
-  GPUStateStack *stack = GPU_context_active_get()->state_stack;
-  auto &state = stack->mutable_stack_top_get();
+  GPUStateManager *stack = GPU_context_active_get()->state_manager;
+  auto &state = stack->mutable_state;
   copy_v2_fl2(state.depth_range, near, far);
   /* TODO remove this and only push state at draw time. */
   stack->set_mutable_state(state);
@@ -166,8 +163,8 @@ void GPU_point_size(float size)
 /* TODO remove and use program point size everywhere */
 void GPU_program_point_size(bool enable)
 {
-  GPUStateStack *stack = GPU_context_active_get()->state_stack;
-  auto &state = stack->mutable_stack_top_get();
+  GPUStateManager *stack = GPU_context_active_get()->state_manager;
+  auto &state = stack->mutable_state;
   /* Set point size sign negative to disable. */
   state.point_size = fabsf(state.point_size) * (enable ? 1 : -1);
   /* TODO remove this and only push state at draw time. */
@@ -176,8 +173,8 @@ void GPU_program_point_size(bool enable)
 
 void GPU_scissor_test(bool enable)
 {
-  GPUStateStack *stack = GPU_context_active_get()->state_stack;
-  auto &state = stack->mutable_stack_top_get();
+  GPUStateManager *stack = GPU_context_active_get()->state_manager;
+  auto &state = stack->mutable_state;
   /* Set point size sign negative to disable. */
   state.scissor_rect[2] = abs(state.scissor_rect[2]) * (enable ? 1 : -1);
   /* TODO remove this and only push state at draw time. */
@@ -186,8 +183,8 @@ void GPU_scissor_test(bool enable)
 
 void GPU_scissor(int x, int y, int width, int height)
 {
-  GPUStateStack *stack = GPU_context_active_get()->state_stack;
-  auto &state = stack->mutable_stack_top_get();
+  GPUStateManager *stack = GPU_context_active_get()->state_manager;
+  auto &state = stack->mutable_state;
   int scissor_rect[4] = {x, y, width, height};
   copy_v4_v4_int(state.scissor_rect, scissor_rect);
   /* TODO remove this and only push state at draw time. */
@@ -196,8 +193,8 @@ void GPU_scissor(int x, int y, int width, int height)
 
 void GPU_viewport(int x, int y, int width, int height)
 {
-  GPUStateStack *stack = GPU_context_active_get()->state_stack;
-  auto &state = stack->mutable_stack_top_get();
+  GPUStateManager *stack = GPU_context_active_get()->state_manager;
+  auto &state = stack->mutable_state;
   int viewport_rect[4] = {x, y, width, height};
   copy_v4_v4_int(state.viewport_rect, viewport_rect);
   /* TODO remove this and only push state at draw time. */
@@ -212,31 +209,31 @@ void GPU_viewport(int x, int y, int width, int height)
 
 eGPUBlend GPU_blend_get()
 {
-  GPUState &state = GPU_context_active_get()->state_stack->stack_top_get();
+  GPUState &state = GPU_context_active_get()->state_manager->state;
   return state.blend;
 }
 
 eGPUWriteMask GPU_write_mask_get()
 {
-  GPUState &state = GPU_context_active_get()->state_stack->stack_top_get();
+  GPUState &state = GPU_context_active_get()->state_manager->state;
   return state.write_mask;
 }
 
 bool GPU_depth_test_enabled()
 {
-  GPUState &state = GPU_context_active_get()->state_stack->stack_top_get();
+  GPUState &state = GPU_context_active_get()->state_manager->state;
   return state.depth_test != GPU_DEPTH_NONE;
 }
 
 void GPU_scissor_get(int coords[4])
 {
-  GPUStateMutable &state = GPU_context_active_get()->state_stack->mutable_stack_top_get();
+  GPUStateMutable &state = GPU_context_active_get()->state_manager->mutable_state;
   copy_v4_v4_int(coords, state.scissor_rect);
 }
 
 void GPU_viewport_size_get_f(float coords[4])
 {
-  GPUStateMutable &state = GPU_context_active_get()->state_stack->mutable_stack_top_get();
+  GPUStateMutable &state = GPU_context_active_get()->state_manager->mutable_state;
   for (int i = 0; i < 4; i++) {
     coords[i] = state.viewport_rect[i];
   }
@@ -244,13 +241,13 @@ void GPU_viewport_size_get_f(float coords[4])
 
 void GPU_viewport_size_get_i(int coords[4])
 {
-  GPUStateMutable &state = GPU_context_active_get()->state_stack->mutable_stack_top_get();
+  GPUStateMutable &state = GPU_context_active_get()->state_manager->mutable_state;
   copy_v4_v4_int(coords, state.viewport_rect);
 }
 
 bool GPU_depth_mask_get(void)
 {
-  GPUState &state = GPU_context_active_get()->state_stack->stack_top_get();
+  GPUState &state = GPU_context_active_get()->state_manager->state;
   return (state.write_mask & GPU_WRITE_DEPTH) != 0;
 }
 
@@ -262,34 +259,6 @@ bool GPU_mipmap_enabled(void)
 
 /** \} */
 
-/* -------------------------------------------------------------------- */
-/** \name GPUStateStack
- * \{ */
-
-void GPUStateStack::push_stack(void)
-{
-  stack[stack_top + 1] = stack[stack_top];
-  stack_top++;
-}
-
-void GPUStateStack::pop_stack(void)
-{
-  stack_top--;
-}
-
-void GPUStateStack::push_mutable_stack(void)
-{
-  mutable_stack[mutable_stack_top + 1] = mutable_stack[mutable_stack_top];
-  mutable_stack_top++;
-}
-
-void GPUStateStack::pop_mutable_stack(void)
-{
-  mutable_stack_top--;
-}
-
-/** \} */
-
 /* -------------------------------------------------------------------- */
 /** \name Context Utils
  * \{ */
diff --git a/source/blender/gpu/intern/gpu_state_private.hh b/source/blender/gpu/intern/gpu_state_private.hh
index 31840724ec0..4326c3a73e5 100644
--- a/source/blender/gpu/intern/gpu_state_private.hh
+++ b/source/blender/gpu/intern/gpu_state_private.hh
@@ -79,6 +79,8 @@ inline GPUState operator^(const GPUState &a, const GPUState &b)
 /* Mutable state that does not require pipeline change. */
 union GPUStateMutable {
   struct {
+    /* Viewport State */
+    /** TODO put inside GPUFramebuffer. */
     /** Offset + Extent of the drawable region inside the framebuffer. */
     int viewport_rect[4];
     /** Offset + Extent of the scissor region inside the framebuffer. */
@@ -126,41 +128,17 @@ inline GPUStateMutable operator^(const GPUStateMutable &a, const GPUStateMutable
   return r;
 }
 
-#define GPU_STATE_STACK_LEN 4
-
-class GPUStateStack {
- private:
-  /** Stack of state for quick temporary modification of the state. */
-  GPUState stack[GPU_STATE_STACK_LEN];
-  GPUStateMutable mutable_stack[GPU_STATE_STACK_LEN];
-  int stack_top = 0;
-  int mutable_stack_top = 0;
+class GPUStateManager {
+ public:
+  GPUState state;
+  GPUStateMutable mutable_state;
 
  public:
-  virtual ~GPUStateStack(){};
+  virtual ~GPUStateManager(){};
 
-  virtual void set_state(GPUState &state) = 0;
-  virtual void set_mutable_state(GPUStateMutable &state) = 0;
-
-  void push_stack(void);
-  void pop_stack(void);
-
-  void push_mutable_stack(void);
-  void pop_mutable_stack(void);
-
-  inline GPUState &stack_top_get(void);
-  inline GPUStateMutable &mutable_stack_top_get(void);
+  virtual void set_state(const GPUState &state) = 0;
+  virtual void set_mutable_state(const GPUStateMutable &state) = 0;
 };
 
-inline GPUState &GPUStateStack::stack_top_get(void)
-{
-  return stack[stack_top];
-}
-
-inline GPUStateMutable &GPUStateStack::mutable_stack_top_get(void)
-{
-  return mutable_stack[mutable_stack_top];
-}
-
 }  // namespace gpu
 }  // namespace blender
diff --git a/source/blender/gpu/opengl/gl_context.cc b/source/blender/gpu/opengl/gl_context.cc
index 168799fb3d6..11f313f639b 100644
--- a/source/blender/gpu/opengl/gl_context.cc
+++ b/source/blender/gpu/opengl/gl_context.cc
@@ -57,7 +57,7 @@ GLContext::GLContext(void *ghost_window, GLSharedOrphanLists &shared_orphan_list
   glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
   glBindBuffer(GL_ARRAY_BUFFER, 0);
 
-  state_stack = new GLStateStack();
+  state_manager = new GLStateManager();
 }
 
 GLContext::~GLContext()
diff --git a/source/blender/gpu/opengl/gl_state.cc b/source/blender/gpu/opengl/gl_state.cc
index 32bc66c4dda..f4360f51527 100644
--- a/source/blender/gpu/opengl/gl_state.cc
+++ b/source/blender/gpu/opengl/gl_state.cc
@@ -21,23 +21,20 @@
  */
 
 #include "BLI_math_base.h"
-#include "BLI_utildefines.h"
-
-#include "BKE_global.h"
 
 #include "GPU_extensions.h"
-#include "GPU_glew.h"
-#include "GPU_state.h"
+
+#include "glew-mx.h"
 
 #include "gl_state.hh"
 
 using namespace blender::gpu;
 
 /* -------------------------------------------------------------------- */
-/** \name GLStateStack
+/** \name GLStateManager
  * \{ */
 
-void GLStateStack::set_state(GPUState &state)
+void GLStateManager::set_state(const GPUState &state)
 {
   GPUState changed = state ^ current_;
 
@@ -52,7 +49,7 @@ void GLStateStack::set_state(GPUState &state)
   }
   if (changed.stencil_test != 0 || changed.stencil_op != 0) {
     set_stencil_test(state.stencil_test, state.stencil_op);
-    set_stencil_mask(state.stencil_test, mutable_stack_top_get());
+    set_stencil_mask(state.stencil_test, mutable_state);
   }
   if (changed.clip_distances != 0) {
     set_clip_distances(state.clip_distances, current_.clip_distances);
@@ -94,11 +91,14 @@ void GLStateStack::set_state(GPUState &state)
   current_ = state;
 }
 
-void GLStateStack::set_mutable_state(GPUStateMutable &state)
+void GLStateManager::set_mutable_state(const GPUStateMutable &state)
 {
   GPUStateMutable changed = state ^ current_mutable_;
 
-  glViewport(UNPACK4(state.viewport_rect));
+  if ((changed.viewport_rect[0] != 0) || (changed.viewport_rect[1] != 0) ||
+      (changed.viewport_rect[2] != 0) || (changed.viewport_rect[3] != 0)) {
+    glViewport(UNPACK4(state.viewport_rect));
+  }
 
   if ((changed.scissor_rect[0] != 0) || (changed.scissor_rect[1] != 0) ||
       (changed.scissor_rect[2] != 0) || (changed.scissor_rect[3] != 0)) {
@@ -113,12 +113,14 @@ void GLStateStack::set_mutable_state(GPUStateMutable &state)
   }
 
   /* TODO remove, should be uniform. */
-  if (state.point_size > 0.0f) {
-    glEnable(GL_PROGRAM_POINT_SIZE);
-    glPointSize(state.point_size);
-  }
-  else {
-    glDisable(GL_PROGRAM_POINT_SIZE);
+  if (changed.point_size != 0) {
+    if (state.point_size > 0.0f) {
+      glEnable(GL_PROGRAM_POINT_SIZE);
+      glPointSize(state.point_size);
+    }
+    else {
+      glDisable(GL_PROGRAM_POINT_SIZE);
+    }
   }
 
   if (changed.line_width != 0) {
@@ -145,7 +147,7 @@ void GLStateStack::set_mutable_state(GPUStateMutable &state)
 /** \name State set functions
  * \{ */
 
-void GLStateStack::set_write_mask(const eGPUWriteMask value)
+void GLStateManager::set_write_mask(const eGPUWriteMask value)
 {
   glDepthMask((value & GPU_WRITE_DEPTH) != 0);
   glColorMask((value & GPU_WRITE_RED) != 0,
@@ -154,7 +156,7 @@ void GLStateStack::set_write_mask(const eGPUWriteMask value)
               (value & GPU_WRITE_ALPHA) != 0);
 }
 
-void GLStateStack::set_depth_test(const eGPUDepthTest value)
+void GLStateManager::set_depth_test(const eGPUDepthTest value)
 {
   GLenum func;
   switch (value) {
@@ -188,7 +190,7 @@ void GLStateStack::set_depth_test(const eGPUDepthTest value)
   }
 }
 
-void GLStateStack::set_stencil_test(const eGPUStencilTest test, const eGPUStencilOp operation)
+void GLStateManager::set_stencil_test(const eGPUStencilTest test, const eGPUStencilOp operation)
 {
   switch (operation) {
     case GPU_STENCIL_OP_REPLACE:
@@ -215,7 +217,7 @@ void GLStateStack::set_stencil_test(const eGPUStencilTest test, const eGPUStenci
   }
 }
 
-void GLStateStack::set_stencil_mask(const eGPUStencilTest test, const GPUStateMutable state)
+void GLStateManager::set_stencil_mask(const eGPUStencilTest test, const GPUStateMutable state)
 {
   GLenum func;
   switch (test) {
@@ -239,7 +241,7 @@ void GLStateStack::set_stencil_mask(const eGPUStencilTest test, const GPUStateMu
   glStencilFunc(func, state.stencil_reference, state.stencil_compare_mask);
 }
 
-void GLStateStack::set_clip_distances(const int new_dist_len, const int old_dist_len)
+void GLStateManager::set_clip_distances(const int new_dist_len, const int old_dist_len)
 {
   for (int i = 0; i < new_dist_len; i++) {
     glEnable(GL_CLIP_DISTANCE0 + i);
@@ -249,7 +251,7 @@ void GLStateStack::set_clip_distances(const int new_dist_len, const int old_dist
   }
 }
 
-void GLStateStack::set_logic_op(const bool enable)
+void GLStateManager::set_logic_op(const bool enable)
 {
   if (enable) {
     glEnable(GL_COLOR_LOGIC_OP);
@@ -260,12 +262,12 @@ void GLStateStack::set_logic_op(const bool enable)
   }
 }
 
-void GLStateStack::set_facing(const bool invert)
+void GLStateManager::set_facing(const bool invert)
 {
   glFrontFace((invert) ? GL_CW : GL_CCW);
 }
 
-void GLStateStack::set_backface_culling(const eGPUFaceCullTest test)
+void GLStateManager::set_backface_culling(const eGPUFaceCullTest test)
 {
   if (test != GPU_CULL_NONE) {
     glDisable(GL_CULL_FACE);
@@ -276,14 +278,14 @@ void GLStateStack::set_backface_culling(const eGPUFaceCullTest test)
   }
 }
 
-void GLStateStack::set_provoking_vert(const eGPUProvokingVertex vert)
+void GLStateManager::set_provoking_vert(const eGPUProvokingVertex vert)
 {
   GLenum value = (vert == GPU_VERTEX_FIRST) ? GL_FIRST_VERTEX_CONVENTION :
                                               GL_LAST_VERTEX_CONVENTION;
   glProvokingVertex(value);
 }
 
-void GLStateStack::set_shadow_bias(const bool enable)
+void GLStateManager::set_shadow_bias(const bool enable)
 {
   if (enable) {
     glEnable(GL_POLYGON_OFFSET_FILL);
@@ -297,7 +299,7 @@ void GLStateStack::set_shadow_bias(const bool enable)
   }
 }
 
-void GLStateStack::set_blend(const eGPUBlend value)
+void GLStateManager::set_blend(const eGPUBlend value)
 {
   /**
    * Factors to the equation.
diff --git a/source/blender/gpu/opengl/gl_state.hh b/source/blender/gpu/opengl/gl_state.hh
index 577e8f9eb1c..5b8e687425d 100644
--- a/source/blender/gpu/opengl/gl_state.hh
+++ b/source/blender/gpu/opengl/gl_state.hh
@@ -31,18 +31,17 @@
 namespace blender {
 namespace gpu {
 
-class GLStateStack : public GPUStateStack {
+class GLStateManager : public GPUStateManager {
  private:
   /** Current state of the GL implementation. Avoids resetting the whole state for every change. */
   GPUState current_;
   GPUStateMutable current_mutable_;
 
  public:
-  void set_state(GPUState &state) override;
-  void set_mutable_state(GPUStateMutable &state) override;
+  void set_state(const GPUState &state) override;
+  void set_mutable_state(const GPUStateMutable &state) override;
 
- public:
-  /* TODO to become private */
+ private:
   static void set_write_mask(const eGPUWriteMask value);
   static void set_depth_test(const eGPUDepthTest value);
   static void set_stencil_test(const eGPUStencilTest test, const eGPUStencilOp operation);
@@ -55,7 +54,7 @@ class GLStateStack : public GPUStateStack {
   static void set_shadow_bias(const bool enable);
   static void set_blend(const eGPUBlend value);
 
-  MEM_CXX_CLASS_ALLOC_FUNCS("GLStateStack")
+  MEM_CXX_CLASS_ALLOC_FUNCS("GLStateManager")
 };
 
 }  // namespace gpu