GPUVertBuf: GL Backend Isolation

Part of the Vulkan port T68990

This makes a few changes in how the data is being handled by the
backend to allow more flexibility in the future.

The overall code logic is left unchanged.

5 files changed, 75 insertions, 21 deletions

diff --git a/source/blender/gpu/opengl/gl_shader.cc b/source/blender/gpu/opengl/gl_shader.cc
index 1d74400bc4c..9136a1d9714 100644
--- a/source/blender/gpu/opengl/gl_shader.cc
+++ b/source/blender/gpu/opengl/gl_shader.cc
@@ -270,9 +270,9 @@ bool GLShader::transform_feedback_enable(GPUVertBuf *buf_)
 
   GLVertBuf *buf = static_cast<GLVertBuf *>(unwrap(buf_));
 
-  BLI_assert(buf->vbo_id != 0);
+  BLI_assert(buf->vbo_id_ != 0);
 
-  glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, buf->vbo_id);
+  glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, buf->vbo_id_);
 
   switch (transform_feedback_type_) {
     case GPU_SHADER_TFB_POINTS:
diff --git a/source/blender/gpu/opengl/gl_texture.cc b/source/blender/gpu/opengl/gl_texture.cc
index 6151a2fc73e..6cff97215e8 100644
--- a/source/blender/gpu/opengl/gl_texture.cc
+++ b/source/blender/gpu/opengl/gl_texture.cc
@@ -120,10 +120,10 @@ bool GLTexture::init_internal(GPUVertBuf *vbo)
   GLenum internal_format = to_gl_internal_format(format_);
 
   if (GLEW_ARB_direct_state_access) {
-    glTextureBuffer(tex_id_, internal_format, gl_vbo->vbo_id);
+    glTextureBuffer(tex_id_, internal_format, gl_vbo->vbo_id_);
   }
   else {
-    glTexBuffer(target_, internal_format, gl_vbo->vbo_id);
+    glTexBuffer(target_, internal_format, gl_vbo->vbo_id_);
   }
 
 #ifndef __APPLE__
diff --git a/source/blender/gpu/opengl/gl_vertex_array.cc b/source/blender/gpu/opengl/gl_vertex_array.cc
index 463dc18cc60..4e49828d39d 100644
--- a/source/blender/gpu/opengl/gl_vertex_array.cc
+++ b/source/blender/gpu/opengl/gl_vertex_array.cc
@@ -122,7 +122,7 @@ void GLVertArray::update_bindings(const GLuint vao,
   for (int v = GPU_BATCH_VBO_MAX_LEN - 1; v > -1; v--) {
     GLVertBuf *vbo = batch->verts_(v);
     if (vbo) {
-      GPU_vertbuf_use(batch->verts[v]);
+      vbo->bind();
       attr_mask &= ~vbo_bind(interface, &vbo->format, 0, vbo->vertex_len, false);
     }
   }
@@ -130,7 +130,7 @@ void GLVertArray::update_bindings(const GLuint vao,
   for (int v = GPU_BATCH_INST_VBO_MAX_LEN - 1; v > -1; v--) {
     GLVertBuf *vbo = batch->inst_(v);
     if (vbo) {
-      GPU_vertbuf_use(batch->inst[v]);
+      vbo->bind();
       attr_mask &= ~vbo_bind(interface, &vbo->format, base_instance, vbo->vertex_len, true);
     }
   }
diff --git a/source/blender/gpu/opengl/gl_vertex_buffer.cc b/source/blender/gpu/opengl/gl_vertex_buffer.cc
index ee9e0a0b0c9..66ff1f36cef 100644
--- a/source/blender/gpu/opengl/gl_vertex_buffer.cc
+++ b/source/blender/gpu/opengl/gl_vertex_buffer.cc
@@ -27,30 +27,83 @@
 
 namespace blender::gpu {
 
-void GLVertBuf::bind(void)
+void GLVertBuf::acquire_data(void)
 {
+  /* Discard previous data if any. */
+  MEM_SAFE_FREE(data);
+  data = (uchar *)MEM_mallocN(sizeof(uchar) * this->size_alloc_get(), __func__);
 }
 
-void GLVertBuf::upload_data(void)
+void GLVertBuf::resize_data(void)
 {
+  data = (uchar *)MEM_reallocN(data, sizeof(uchar) * this->size_alloc_get());
 }
 
-uchar *GLVertBuf::acquire_data(void)
+void GLVertBuf::release_data(void)
 {
-  return nullptr;
+  if (vbo_id_ != 0) {
+    GLBackend::get()->buf_free(vbo_id_);
+    vbo_id_ = 0;
+    memory_usage -= vbo_size_;
+  }
+
+  MEM_SAFE_FREE(data);
 }
 
-uchar *GLVertBuf::resize_data(void)
+void GLVertBuf::duplicate_data(VertBuf *dst_)
 {
-  return nullptr;
+  BLI_assert(GPU_context_active_get() != NULL);
+  GLVertBuf *src = this;
+  GLVertBuf *dst = static_cast<GLVertBuf *>(dst_);
+
+  if (src->vbo_id_ != 0) {
+    dst->vbo_size_ = src->size_used_get();
+
+    glGenBuffers(1, &dst->vbo_id_);
+    glBindBuffer(GL_COPY_WRITE_BUFFER, dst->vbo_id_);
+    glBufferData(GL_COPY_WRITE_BUFFER, dst->vbo_size_, NULL, to_gl(dst->usage_));
+
+    glBindBuffer(GL_COPY_READ_BUFFER, src->vbo_id_);
+
+    glCopyBufferSubData(GL_COPY_READ_BUFFER, GL_COPY_WRITE_BUFFER, 0, 0, dst->vbo_size_);
+
+    memory_usage += dst->vbo_size_;
+  }
+
+  if (data != nullptr) {
+    dst->data = (uchar *)MEM_dupallocN(src->data);
+  }
 }
 
-void GLVertBuf::release_data(void)
+void GLVertBuf::upload_data(void)
 {
+  this->bind();
 }
 
-void GLVertBuf::duplicate_data(VertBuf *)
+void GLVertBuf::bind(void)
 {
+  BLI_assert(GPU_context_active_get() != NULL);
+
+  if (vbo_id_ == 0) {
+    glGenBuffers(1, &vbo_id_);
+  }
+
+  glBindBuffer(GL_ARRAY_BUFFER, vbo_id_);
+
+  if (flag & GPU_VERTBUF_DATA_DIRTY) {
+    vbo_size_ = this->size_used_get();
+    /* Orphan the vbo to avoid sync then upload data. */
+    glBufferData(GL_ARRAY_BUFFER, vbo_size_, NULL, to_gl(usage_));
+    glBufferSubData(GL_ARRAY_BUFFER, 0, vbo_size_, data);
+
+    memory_usage += vbo_size_;
+
+    if (usage_ == GPU_USAGE_STATIC) {
+      MEM_SAFE_FREE(data);
+    }
+    flag &= ~GPU_VERTBUF_DATA_DIRTY;
+    flag |= GPU_VERTBUF_DATA_UPLOADED;
+  }
 }
 
 }  // namespace blender::gpu
\ No newline at end of file
diff --git a/source/blender/gpu/opengl/gl_vertex_buffer.hh b/source/blender/gpu/opengl/gl_vertex_buffer.hh
index 76c5e86a1c7..eee5222f467 100644
--- a/source/blender/gpu/opengl/gl_vertex_buffer.hh
+++ b/source/blender/gpu/opengl/gl_vertex_buffer.hh
@@ -37,19 +37,20 @@ class GLVertBuf : public VertBuf {
   friend class GLShader;  /* For transform feedback. */
 
  private:
-  // GLuint vbo_id_ = 0;
+  /** OpenGL buffer handle. Init on first upload. Immutable after that. */
+  GLuint vbo_id_ = 0;
   /** Size on the GPU. */
-  // size_t vbo_size_ = 0;
+  size_t vbo_size_ = 0;
 
  public:
   void bind(void);
 
  protected:
-  uchar *acquire_data(void);
-  uchar *resize_data(void);
-  void release_data(void);
-  void upload_data(void);
-  void duplicate_data(VertBuf *dst);
+  void acquire_data(void) override;
+  void resize_data(void) override;
+  void release_data(void) override;
+  void upload_data(void) override;
+  void duplicate_data(VertBuf *dst) override;
 
   MEM_CXX_CLASS_ALLOC_FUNCS("GLVertBuf");
 };