Python GPU: Add reference of PyObject GPU object to the GPU object itself

Instead of creating different python wrappers for the same GPU object,
return the same `PyObject` created earlier.

This also allows for more secure access to existing GPU objects.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D11044

source/blender/gpu/GPU_common.h

@@ -24,6 +24,7 @@
 #pragma once
 
 #define PROGRAM_NO_OPTI 0
+#define USE_PY_REFERENCES 1
 
 #if defined(NDEBUG)
 #  define TRUST_NO_ONE 0

source/blender/gpu/GPU_framebuffer.h

@@ -209,6 +209,11 @@ void GPU_framebuffer_recursive_downsample(GPUFrameBuffer *fb,
                                           void (*callback)(void *userData, int level),
                                           void *userData);
 
+#if USE_PY_REFERENCES
+void **GPU_framebuffer_py_reference_get(GPUFrameBuffer *gpu_fb);
+void GPU_framebuffer_py_reference_set(GPUFrameBuffer *gpu_fb, void **py_ref);
+#endif
+
 void GPU_framebuffer_push(GPUFrameBuffer *fb);
 GPUFrameBuffer *GPU_framebuffer_pop(void);
 uint GPU_framebuffer_stack_level_get(void);

source/blender/gpu/GPU_texture.h

@@ -269,6 +269,12 @@ bool GPU_texture_cube(const GPUTexture *tex);
 bool GPU_texture_depth(const GPUTexture *tex);
 bool GPU_texture_stencil(const GPUTexture *tex);
 bool GPU_texture_integer(const GPUTexture *tex);
+
+#if USE_PY_REFERENCES
+void **GPU_texture_py_reference_get(GPUTexture *tex);
+void GPU_texture_py_reference_set(GPUTexture *tex, void **py_ref);
+#endif
+
 int GPU_texture_opengl_bindcode(const GPUTexture *tex);
 
 void GPU_texture_get_mipmap_size(GPUTexture *tex, int lvl, int *size);

source/blender/gpu/intern/gpu_framebuffer.cc

@@ -71,6 +71,12 @@ FrameBuffer::~FrameBuffer()
       reinterpret_cast<Texture *>(attachment.tex)->detach_from(this);
     }
   }
+
+#if USE_PY_REFERENCES
+  if (this->py_ref) {
+    *this->py_ref = nullptr;
+  }
+#endif
 }
 
 /** \} */
@@ -473,6 +479,19 @@ void GPU_framebuffer_recursive_downsample(GPUFrameBuffer *gpu_fb,
   unwrap(gpu_fb)->recursive_downsample(max_lvl, callback, userData);
 }
 
+#if USE_PY_REFERENCES
+void **GPU_framebuffer_py_reference_get(GPUFrameBuffer *gpu_fb)
+{
+  return unwrap(gpu_fb)->py_ref;
+}
+
+void GPU_framebuffer_py_reference_set(GPUFrameBuffer *gpu_fb, void **py_ref)
+{
+  BLI_assert(ref == nullptr || unwrap(gpu_fb)->py_ref == nullptr);
+  unwrap(gpu_fb)->py_ref = py_ref;
+}
+#endif
+
 /** \} */
 
 /* -------------------------------------------------------------------- */

source/blender/gpu/intern/gpu_framebuffer_private.hh

@@ -100,6 +100,15 @@ class FrameBuffer {
   bool scissor_test_ = false;
   bool dirty_state_ = true;
 
+#if USE_PY_REFERENCES
+ public:
+  /**
+   * Reference of a pointer that needs to be cleaned when deallocating the frame-buffer.
+   * Points to #BPyGPUFrameBuffer.fb
+   */
+  void **py_ref = nullptr;
+#endif
+
  public:
   FrameBuffer(const char *name);
   virtual ~FrameBuffer();

source/blender/gpu/intern/gpu_texture.cc

@@ -60,6 +60,12 @@ Texture::~Texture()
       fb_[i]->attachment_remove(fb_attachment_[i]);
     }
   }
+
+#if USE_PY_REFERENCES
+  if (this->py_ref) {
+    *this->py_ref = nullptr;
+  }
+#endif
 }
 
 bool Texture::init_1D(int w, int layers, eGPUTextureFormat format)
@@ -581,6 +587,19 @@ bool GPU_texture_array(const GPUTexture *tex)
   return (reinterpret_cast<const Texture *>(tex)->type_get() & GPU_TEXTURE_ARRAY) != 0;
 }
 
+#if USE_PY_REFERENCES
+void **GPU_texture_py_reference_get(GPUTexture *tex)
+{
+  return unwrap(tex)->py_ref;
+}
+
+void GPU_texture_py_reference_set(GPUTexture *tex, void **py_ref)
+{
+  BLI_assert(py_ref == nullptr || unwrap(tex)->py_ref == nullptr);
+  unwrap(tex)->py_ref = py_ref;
+}
+#endif
+
 /* TODO remove */
 int GPU_texture_opengl_bindcode(const GPUTexture *tex)
 {

source/blender/gpu/intern/gpu_texture_private.hh

@@ -80,6 +80,13 @@ class Texture {
   int refcount = 1;
   /** Width & Height (of source data), optional. */
   int src_w = 0, src_h = 0;
+#if USE_PY_REFERENCES
+  /**
+   * Reference of a pointer that needs to be cleaned when deallocating the texture.
+   * Points to #BPyGPUTexture.tex
+   */
+  void **py_ref = nullptr;
+#endif
 
  protected:
   /* ---- Texture format (immutable after init). ---- */