UPBGE: Use GPUBuffer in RAS_InstancingBuffer.

Using GPUBuffer allow to reuse existing and frequently maintained code
from the viewport. The only issue encountered was for resize the VBO.
The GPUBuffer is not able to be resized, but reallocated instead.
The reallocation is not a problems as the viewport use a pool of all
freed GPUbuffers and reuse it in some case.
The reallocation is done in RAS_InstancingBuffer::Realloc(). None
performance decrease was noticed.

source/gameengine/Rasterizer/CMakeLists.txt

@@ -32,6 +32,7 @@ set(INC
 	../../blender/makesdna
 	../../blender/blenlib
 	../../blender/blenkernel
+	../../blender/gpu
 	../../blender/imbuf
 	../../../intern/glew-mx
 	../../../intern/guardedalloc

source/gameengine/Rasterizer/RAS_DisplayArrayBucket.cpp

@@ -282,7 +282,7 @@ void RAS_DisplayArrayBucket::RenderMeshSlotsInstancing(const MT_Transform& camer
 	UpdateActiveMeshSlots(rasty);
 
 	// Bind the instancing buffer to work on it.
-	m_instancingBuffer->Bind();
+	m_instancingBuffer->Realloc(nummeshslots);
 
 	/* If the material use the transparency we must sort all mesh slots depending on the distance.
 	 * This code share the code used in RAS_BucketManager to do the sort.
@@ -309,6 +309,8 @@ void RAS_DisplayArrayBucket::RenderMeshSlotsInstancing(const MT_Transform& camer
 		m_instancingBuffer->Update(rasty, material->GetDrawingMode(), m_activeMeshSlots);
 	}
 
+	m_instancingBuffer->Bind();
+
 	// Bind all vertex attributs for the used material and the given buffer offset.
 	if (rasty->GetOverrideShader() == RAS_IRasterizer::RAS_OVERRIDE_SHADER_NONE) {
 		material->ActivateInstancing(

source/gameengine/Rasterizer/RAS_InstancingBuffer.cpp

@@ -29,40 +29,53 @@
 #include "RAS_InstancingBuffer.h"
 #include "RAS_IRasterizer.h"
 #include "RAS_MeshUser.h"
-#include "glew-mx.h"
+
+extern "C" {
+	// To avoid include BKE_DerivedMesh.h.
+	typedef int (*DMSetMaterial)(int mat_nr, void *attribs);
+	#include "GPU_buffers.h"
+}
 
 RAS_InstancingBuffer::RAS_InstancingBuffer()
-	:m_matrixOffset(NULL),
+	:m_vbo(NULL),
+	m_matrixOffset(NULL),
 	m_positionOffset(NULL),
 	m_colorOffset(NULL),
 	m_stride(sizeof(RAS_InstancingBuffer::InstancingObject))
 {
-	glGenBuffersARB(1, &m_vbo);
-
 	m_matrixOffset = (void *)((InstancingObject *)NULL)->matrix;
 	m_positionOffset = (void *)((InstancingObject *)NULL)->position;
 	m_colorOffset = (void *)((InstancingObject *)NULL)->color;
 }
 
 RAS_InstancingBuffer::~RAS_InstancingBuffer()
 {
-	glDeleteBuffersARB(1, &m_vbo);
+	if (m_vbo) {
+		GPU_buffer_free(m_vbo);
+	}
+}
+
+void RAS_InstancingBuffer::Realloc(unsigned int size)
+{
+	if (m_vbo) {
+		GPU_buffer_free(m_vbo);
+	}
+	m_vbo = GPU_buffer_alloc(m_stride * size);
 }
 
 void RAS_InstancingBuffer::Bind()
 {
-	glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
+	GPU_buffer_bind(m_vbo, GPU_BINDING_ARRAY);
 }
 
 void RAS_InstancingBuffer::Unbind()
 {
-	glBindBuffer(GL_ARRAY_BUFFER, 0);
+	GPU_buffer_unbind(m_vbo, GPU_BINDING_ARRAY);
 }
 
 void RAS_InstancingBuffer::Update(RAS_IRasterizer *rasty, int drawingmode, RAS_MeshSlotList &meshSlots)
 {
-	glBufferData(GL_ARRAY_BUFFER, sizeof(InstancingObject) * meshSlots.size(), 0, GL_DYNAMIC_DRAW);
-	InstancingObject *buffer = (InstancingObject *)glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
+	InstancingObject *buffer = (InstancingObject *)GPU_buffer_lock_stream(m_vbo, GPU_BINDING_ARRAY);
 
 	for (unsigned int i = 0, size = meshSlots.size(); i < size; ++i) {
 		RAS_MeshSlot *ms = meshSlots[i];
@@ -90,5 +103,5 @@ void RAS_InstancingBuffer::Update(RAS_IRasterizer *rasty, int drawingmode, RAS_M
 		data.color[3] = color[3] * 255.0f;
 	}
 
-	glUnmapBuffer(GL_ARRAY_BUFFER);
+	GPU_buffer_unlock(m_vbo, GPU_BINDING_ARRAY);
 }

source/gameengine/Rasterizer/RAS_InstancingBuffer.h

@@ -33,10 +33,12 @@
 
 class RAS_IRasterizer;
 
+struct GPUBuffer;
+
 class RAS_InstancingBuffer
 {
-	/// The OpenGL VBO identificator.
-	unsigned int m_vbo;
+	/// The OpenGL VBO.
+	GPUBuffer *m_vbo;
 	/// The matrix offset in the VBO.
 	void *m_matrixOffset;
 	/// The position offset in the VBO.
@@ -58,6 +60,8 @@ class RAS_InstancingBuffer
 	RAS_InstancingBuffer();
 	virtual ~RAS_InstancingBuffer();
 
+	/// Realloc the VBO.
+	void Realloc(unsigned int size);
 	/// Bind the VBO before work on it.
 	void Bind();
 	/// Unbind the VBO after work on it.