GPUTexture: GL Backend Isolation

This is a massive cleanup needed for vulkan support T68990. It provides:

- More meaningful enums with conversion functions.
- Less hacky supports of arrays and cubemaps (all considered layered).
- More inline with the stateless design of vulkan and modern GL.
- Methods Fallbacks are using framebuffer functions that are wrapped
  instead of implementing inside the texture module.

What is not in there:
- API change.
- Samplers support (breaks a few effects).

# Conflicts:
#	source/blender/gpu/GPU_texture.h

1 files changed, 22 insertions, 0 deletions

diff --git a/source/blender/gpu/opengl/gl_state.hh b/source/blender/gpu/opengl/gl_state.hh
index c25e384fcd7..2befad690f0 100644
--- a/source/blender/gpu/opengl/gl_state.hh
+++ b/source/blender/gpu/opengl/gl_state.hh
@@ -20,6 +20,8 @@
  * \ingroup gpu
  */
 
+#pragma once
+
 #include "MEM_guardedalloc.h"
 
 #include "BLI_utildefines.h"
@@ -32,6 +34,7 @@ namespace blender {
 namespace gpu {
 
 class GLFrameBuffer;
+class GLTexture;
 
 /**
  * State manager keeping track of the draw state and applying it before drawing.
@@ -49,11 +52,28 @@ class GLStateManager : public GPUStateManager {
   /** Limits. */
   float line_width_range_[2];
 
+  /** Texture state:
+   * We keep the full stack of textures and sampler bounds to use multi bind, and to be able to
+   * edit and restore texture binds on the fly without querying the context.
+   * Also this allows us to keep track of textures bounds to many texture units.
+   * Keep the targets to know what target to set to 0 for unbinding (legacy).
+   * Init first target to GL_TEXTURE_2D for texture_bind_temp to work.
+   */
+  GLuint targets_[64] = {GL_TEXTURE_2D};
+  GLuint textures_[64] = {0};
+  GLuint samplers_[64] = {0};
+  uint64_t dirty_texture_binds_ = 0;
+
  public:
   GLStateManager();
 
   void apply_state(void) override;
 
+  void texture_bind(Texture *tex, eGPUSamplerState sampler, int unit) override;
+  void texture_bind_temp(GLTexture *tex);
+  void texture_unbind(Texture *tex) override;
+  void texture_unbind_all(void) override;
+
  private:
   static void set_write_mask(const eGPUWriteMask value);
   static void set_depth_test(const eGPUDepthTest value);
@@ -70,6 +90,8 @@ class GLStateManager : public GPUStateManager {
   void set_state(const GPUState &state);
   void set_mutable_state(const GPUStateMutable &state);
 
+  void texture_bind_apply(void);
+
   MEM_CXX_CLASS_ALLOC_FUNCS("GLStateManager")
 };