Cleanup GPU: get rid of some extremely legacy draw code.

Basically this commit gets rid of most of the derived mesh immediate mode
drawing (cases such as subsurf excluded). Even when VBO is turned off
in user preferences, we still use vertex arrays, which are very similar to
VBOs but memory is client side. Vertex arrays are OpenGL 1.1 so compatibility
is not an issue here.

Reviewers: campbellbarton, sergey, jwilkins

Differential Revision: https://developer.blender.org/D919

2 files changed, 70 insertions, 79 deletions

diff --git a/source/blender/gpu/GPU_buffers.h b/source/blender/gpu/GPU_buffers.h
index ba461d5f8a2..e9b600a9267 100644
--- a/source/blender/gpu/GPU_buffers.h
+++ b/source/blender/gpu/GPU_buffers.h
@@ -54,6 +54,7 @@ typedef struct GPUBuffer {
 	int size;	/* in bytes */
 	void *pointer;	/* used with vertex arrays */
 	unsigned int id;	/* used with vertex buffer objects */
+	bool use_vbo;	/* true for VBOs, false for vertex arrays */
 } GPUBuffer;
 
 typedef struct GPUBufferMaterial {
@@ -85,6 +86,7 @@ typedef struct GPUDrawObject {
 	GPUBuffer *points;
 	GPUBuffer *normals;
 	GPUBuffer *uv;
+	GPUBuffer *uv_tex;
 	GPUBuffer *colors;
 	GPUBuffer *edges;
 	GPUBuffer *uvedges;
@@ -113,10 +115,6 @@ typedef struct GPUDrawObject {
 	/* caches of the original DerivedMesh values */
 	int totvert;
 	int totedge;
-
-	/* if there was a failure allocating some buffer, use old
-	 * rendering code */
-	bool legacy;
 } GPUDrawObject;
 
 /* used for GLSL materials */
@@ -129,7 +127,7 @@ typedef struct GPUAttrib {
 void GPU_global_buffer_pool_free(void);
 void GPU_global_buffer_pool_free_unused(void);
 
-GPUBuffer *GPU_buffer_alloc(int size);
+GPUBuffer *GPU_buffer_alloc(int size, bool force_vertex_arrays);
 void GPU_buffer_free(GPUBuffer *buffer);
 
 GPUDrawObject *GPU_drawobject_new(struct DerivedMesh *dm);
@@ -161,9 +159,6 @@ void GPU_buffer_draw_elements(GPUBuffer *elements, unsigned int mode, int start,
 /* called after drawing */
 void GPU_buffer_unbind(void);
 
-/* used to check whether to use the old (without buffers) code */
-bool GPU_buffer_legacy(struct DerivedMesh *dm);
-
 /* Buffers for non-DerivedMesh drawing */
 typedef struct GPU_PBVH_Buffers GPU_PBVH_Buffers;
 
diff --git a/source/blender/gpu/intern/gpu_buffers.c b/source/blender/gpu/intern/gpu_buffers.c
index b5a576b509c..54743247fea 100644
--- a/source/blender/gpu/intern/gpu_buffers.c
+++ b/source/blender/gpu/intern/gpu_buffers.c
@@ -62,6 +62,8 @@
 
 #include "bmesh.h"
 
+#include "gpu_extensions_private.h"
+
 typedef enum {
 	GPU_BUFFER_VERTEX_STATE = (1 << 0),
 	GPU_BUFFER_NORMAL_STATE = (1 << 1),
@@ -76,7 +78,6 @@ typedef enum {
 #define BUFFER_OFFSET(n) ((GLubyte *)NULL + (n))
 
 /* -1 - undefined, 0 - vertex arrays, 1 - VBOs */
-static int useVBOs = -1;
 static GPUBufferState GLStates = 0;
 static GPUAttrib attribData[MAX_GPU_ATTRIB_DATA] = { { -1, 0, 0 } };
 
@@ -111,10 +112,6 @@ static GPUBufferPool *gpu_buffer_pool_new(void)
 {
 	GPUBufferPool *pool;
 
-	/* enable VBOs if supported */
-	if (useVBOs == -1)
-		useVBOs = (GLEW_ARB_vertex_buffer_object ? 1 : 0);
-
 	pool = MEM_callocN(sizeof(GPUBufferPool), "GPUBuffer_Pool");
 
 	pool->maxsize = MAX_FREE_GPU_BUFFERS;
@@ -158,7 +155,7 @@ static void gpu_buffer_pool_delete_last(GPUBufferPool *pool)
 		return;
 
 	/* delete the buffer's data */
-	if (useVBOs)
+	if (last->use_vbo)
 		glDeleteBuffersARB(1, &last->id);
 	else
 		MEM_freeN(last->pointer);
@@ -226,7 +223,7 @@ void GPU_global_buffer_pool_free_unused(void)
  *
  * Thread-unsafe version for internal usage only.
  */
-static GPUBuffer *gpu_buffer_alloc_intern(int size)
+static GPUBuffer *gpu_buffer_alloc_intern(int size, bool use_VBO)
 {
 	GPUBufferPool *pool;
 	GPUBuffer *buf;
@@ -251,6 +248,10 @@ static GPUBuffer *gpu_buffer_alloc_intern(int size)
 	for (i = 0; i < pool->totbuf; i++) {
 		bufsize = pool->buffers[i]->size;
 
+		/* only return a buffer that matches the VBO preference */
+		 if (pool->buffers[i]->use_vbo != use_VBO)
+			 continue;
+		
 		/* check for an exact size match */
 		if (bufsize == size) {
 			bestfit = i;
@@ -279,8 +280,9 @@ static GPUBuffer *gpu_buffer_alloc_intern(int size)
 	/* no acceptable buffer found in the pool, create a new one */
 	buf = MEM_callocN(sizeof(GPUBuffer), "GPUBuffer");
 	buf->size = size;
+	buf->use_vbo = use_VBO;
 
-	if (useVBOs == 1) {
+	if (use_VBO) {
 		/* create a new VBO and initialize it to the requested
 		 * size */
 		glGenBuffersARB(1, &buf->id);
@@ -307,9 +309,10 @@ static GPUBuffer *gpu_buffer_alloc_intern(int size)
 }
 
 /* Same as above, but safe for threading. */
-GPUBuffer *GPU_buffer_alloc(int size)
+GPUBuffer *GPU_buffer_alloc(int size, bool force_vertex_arrays)
 {
 	GPUBuffer *buffer;
+	bool use_VBOs = (GLEW_ARB_vertex_buffer_object) && !(U.gameflags & USER_DISABLE_VBO) && !force_vertex_arrays;
 
 	if (size == 0) {
 		/* Early out, no lock needed in this case. */
@@ -317,7 +320,7 @@ GPUBuffer *GPU_buffer_alloc(int size)
 	}
 
 	BLI_mutex_lock(&buffer_mutex);
-	buffer = gpu_buffer_alloc_intern(size);
+	buffer = gpu_buffer_alloc_intern(size, use_VBOs);
 	BLI_mutex_unlock(&buffer_mutex);
 
 	return buffer;
@@ -577,6 +580,7 @@ void GPU_drawobject_free(DerivedMesh *dm)
 	GPU_buffer_free(gdo->points);
 	GPU_buffer_free(gdo->normals);
 	GPU_buffer_free(gdo->uv);
+	GPU_buffer_free(gdo->uv_tex);
 	GPU_buffer_free(gdo->colors);
 	GPU_buffer_free(gdo->edges);
 	GPU_buffer_free(gdo->uvedges);
@@ -585,6 +589,22 @@ void GPU_drawobject_free(DerivedMesh *dm)
 	dm->drawObject = NULL;
 }
 
+static GPUBuffer *gpu_try_realloc(GPUBufferPool *pool, GPUBuffer *buffer, int size, bool use_VBOs)
+{
+	gpu_buffer_free_intern(buffer);
+	gpu_buffer_pool_delete_last(pool);
+	buffer = NULL;
+	
+	/* try freeing an entry from the pool
+	 * and reallocating the buffer */
+	if (pool->totbuf > 0) {
+		gpu_buffer_pool_delete_last(pool);
+		buffer = gpu_buffer_alloc_intern(size, use_VBOs);
+	}
+	
+	return buffer;
+}
+
 typedef void (*GPUBufferCopyFunc)(DerivedMesh *dm, float *varray, int *index,
                                   int *mat_orig_to_new, void *user_data);
 
@@ -598,7 +618,7 @@ static GPUBuffer *gpu_buffer_setup(DerivedMesh *dm, GPUDrawObject *object,
 	int *mat_orig_to_new;
 	int *cur_index_per_mat;
 	int i;
-	bool success;
+	bool use_VBOs = (GLEW_ARB_vertex_buffer_object == 1) && !(U.gameflags & USER_DISABLE_VBO);
 	GLboolean uploaded;
 
 	pool = gpu_get_global_buffer_pool();
@@ -606,11 +626,7 @@ static GPUBuffer *gpu_buffer_setup(DerivedMesh *dm, GPUDrawObject *object,
 	BLI_mutex_lock(&buffer_mutex);
 
 	/* alloc a GPUBuffer; fall back to legacy mode on failure */
-	if (!(buffer = gpu_buffer_alloc_intern(size)))
-		dm->drawObject->legacy = 1;
-
-	/* nothing to do for legacy mode */
-	if (dm->drawObject->legacy) {
+	if (!(buffer = gpu_buffer_alloc_intern(size, use_VBOs))) {
 		BLI_mutex_unlock(&buffer_mutex);
 		return NULL;
 	}
@@ -628,8 +644,8 @@ static GPUBuffer *gpu_buffer_setup(DerivedMesh *dm, GPUDrawObject *object,
 		mat_orig_to_new[object->materials[i].mat_nr] = i;
 	}
 
-	if (useVBOs) {
-		success = 0;
+	if (use_VBOs) {
+		bool success = false;
 
 		while (!success) {
 			/* bind the buffer and discard previous data,
@@ -639,32 +655,22 @@ static GPUBuffer *gpu_buffer_setup(DerivedMesh *dm, GPUDrawObject *object,
 
 			/* attempt to map the buffer */
 			if (!(varray = glMapBufferARB(target, GL_WRITE_ONLY_ARB))) {
-				/* failed to map the buffer; delete it */
-				gpu_buffer_free_intern(buffer);
-				gpu_buffer_pool_delete_last(pool);
-				buffer = NULL;
-
-				/* try freeing an entry from the pool
-				 * and reallocating the buffer */
-				if (pool->totbuf > 0) {
-					gpu_buffer_pool_delete_last(pool);
-					buffer = gpu_buffer_alloc_intern(size);
-				}
-
+				 buffer = gpu_try_realloc(pool, buffer, size, true);
+				 
 				/* allocation still failed; fall back
 				 * to legacy mode */
 				if (!buffer) {
-					dm->drawObject->legacy = 1;
-					success = 1;
+					use_VBOs = false;
+					success = true;
 				}
 			}
 			else {
-				success = 1;
+				success = true;
 			}
 		}
 
 		/* check legacy fallback didn't happen */
-		if (dm->drawObject->legacy == 0) {
+		if (use_VBOs) {
 			uploaded = GL_FALSE;
 			/* attempt to upload the data to the VBO */
 			while (uploaded == GL_FALSE) {
@@ -677,15 +683,16 @@ static GPUBuffer *gpu_buffer_setup(DerivedMesh *dm, GPUDrawObject *object,
 		}
 		glBindBufferARB(target, 0);
 	}
-	else {
+	if (!use_VBOs) {
 		/* VBO not supported, use vertex array fallback */
-		if (buffer->pointer) {
+		if (!buffer || !buffer->pointer) {
+			buffer = gpu_try_realloc(pool, buffer, size, false);
+		}
+		
+		if (buffer) {
 			varray = buffer->pointer;
 			(*copy_f)(dm, varray, cur_index_per_mat, mat_orig_to_new, user);
 		}
-		else {
-			dm->drawObject->legacy = 1;
-		}
 	}
 
 	MEM_freeN(cur_index_per_mat);
@@ -1019,7 +1026,7 @@ static GPUBuffer **gpu_drawobject_buffer_from_type(GPUDrawObject *gdo, GPUBuffer
 		case GPU_BUFFER_UV:
 			return &gdo->uv;
 		case GPU_BUFFER_UV_TEXPAINT:
-			return &gdo->uv;
+			return &gdo->uv_tex;
 		case GPU_BUFFER_EDGE:
 			return &gdo->edges;
 		case GPU_BUFFER_UVEDGE:
@@ -1105,7 +1112,7 @@ void GPU_vertex_setup(DerivedMesh *dm)
 		return;
 
 	glEnableClientState(GL_VERTEX_ARRAY);
-	if (useVBOs) {
+	if (dm->drawObject->points->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->points->id);
 		glVertexPointer(3, GL_FLOAT, 0, 0);
 	}
@@ -1122,7 +1129,7 @@ void GPU_normal_setup(DerivedMesh *dm)
 		return;
 
 	glEnableClientState(GL_NORMAL_ARRAY);
-	if (useVBOs) {
+	if (dm->drawObject->normals->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->normals->id);
 		glNormalPointer(GL_FLOAT, 0, 0);
 	}
@@ -1139,7 +1146,7 @@ void GPU_uv_setup(DerivedMesh *dm)
 		return;
 
 	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
-	if (useVBOs) {
+	if (dm->drawObject->uv->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->uv->id);
 		glTexCoordPointer(2, GL_FLOAT, 0, 0);
 	}
@@ -1156,8 +1163,8 @@ void GPU_texpaint_uv_setup(DerivedMesh *dm)
 		return;
 
 	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
-	if (useVBOs) {
-		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->uv->id);
+	if (dm->drawObject->uv_tex->use_vbo) {
+		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->uv_tex->id);
 		glTexCoordPointer(2, GL_FLOAT, 4 * sizeof(float), 0);
 		glClientActiveTexture(GL_TEXTURE2);
 		glEnableClientState(GL_TEXTURE_COORD_ARRAY);
@@ -1165,10 +1172,10 @@ void GPU_texpaint_uv_setup(DerivedMesh *dm)
 		glClientActiveTexture(GL_TEXTURE0);
 	}
 	else {
-		glTexCoordPointer(2, GL_FLOAT, 4 * sizeof(float), dm->drawObject->uv->pointer);
+		glTexCoordPointer(2, GL_FLOAT, 4 * sizeof(float), dm->drawObject->uv_tex->pointer);
 		glClientActiveTexture(GL_TEXTURE2);
 		glEnableClientState(GL_TEXTURE_COORD_ARRAY);
-		glTexCoordPointer(2, GL_FLOAT, 4 * sizeof(float), (char *)dm->drawObject->uv->pointer + 2 * sizeof(float));
+		glTexCoordPointer(2, GL_FLOAT, 4 * sizeof(float), (char *)dm->drawObject->uv_tex->pointer + 2 * sizeof(float));
 		glClientActiveTexture(GL_TEXTURE0);
 	}
 
@@ -1202,7 +1209,7 @@ void GPU_color_setup(DerivedMesh *dm, int colType)
 		return;
 
 	glEnableClientState(GL_COLOR_ARRAY);
-	if (useVBOs) {
+	if (dm->drawObject->colors->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->colors->id);
 		glColorPointer(3, GL_UNSIGNED_BYTE, 0, 0);
 	}
@@ -1222,7 +1229,7 @@ void GPU_edge_setup(DerivedMesh *dm)
 		return;
 
 	glEnableClientState(GL_VERTEX_ARRAY);
-	if (useVBOs) {
+	if (dm->drawObject->edges->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->points->id);
 		glVertexPointer(3, GL_FLOAT, 0, 0);
 	}
@@ -1232,7 +1239,7 @@ void GPU_edge_setup(DerivedMesh *dm)
 	
 	GLStates |= GPU_BUFFER_VERTEX_STATE;
 
-	if (useVBOs)
+	if (dm->drawObject->edges->use_vbo)
 		glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, dm->drawObject->edges->id);
 
 	GLStates |= GPU_BUFFER_ELEMENT_STATE;
@@ -1244,7 +1251,7 @@ void GPU_uvedge_setup(DerivedMesh *dm)
 		return;
 
 	glEnableClientState(GL_VERTEX_ARRAY);
-	if (useVBOs) {
+	if (dm->drawObject->uvedges->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, dm->drawObject->uvedges->id);
 		glVertexPointer(2, GL_FLOAT, 0, 0);
 	}
@@ -1300,7 +1307,7 @@ void GPU_interleaved_attrib_setup(GPUBuffer *buffer, GPUAttrib data[], int numda
 	}
 	elementsize = GPU_attrib_element_size(data, numdata);
 
-	if (useVBOs) {
+	if (buffer->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, buffer->id);
 		for (i = 0; i < numdata; i++) {
 			glEnableVertexAttribArrayARB(data[i].index);
@@ -1343,7 +1350,8 @@ void GPU_buffer_unbind(void)
 	if (GLStates & GPU_BUFFER_COLOR_STATE)
 		glDisableClientState(GL_COLOR_ARRAY);
 	if (GLStates & GPU_BUFFER_ELEMENT_STATE) {
-		if (useVBOs) {
+		/* not guaranteed we used VBOs but in that case it's just a no-op */
+		if (GLEW_ARB_vertex_buffer_object) {
 			glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, 0);
 		}
 	}
@@ -1359,7 +1367,8 @@ void GPU_buffer_unbind(void)
 			break;
 	}
 
-	if (useVBOs)
+	/* not guaranteed we used VBOs but in that case it's just a no-op */
+	if (GLEW_ARB_vertex_buffer_object)
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0);
 }
 
@@ -1377,19 +1386,6 @@ void GPU_color_switch(int mode)
 	}
 }
 
-/* return 1 if drawing should be done using old immediate-mode
- * code, 0 otherwise */
-bool GPU_buffer_legacy(DerivedMesh *dm)
-{
-	int test = (U.gameflags & USER_DISABLE_VBO);
-	if (test)
-		return 1;
-
-	if (dm->drawObject == NULL)
-		dm->drawObject = GPU_drawobject_new(dm);
-	return dm->drawObject->legacy;
-}
-
 void *GPU_buffer_lock(GPUBuffer *buffer)
 {
 	float *varray;
@@ -1397,7 +1393,7 @@ void *GPU_buffer_lock(GPUBuffer *buffer)
 	if (!buffer)
 		return 0;
 
-	if (useVBOs) {
+	if (buffer->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, buffer->id);
 		varray = glMapBufferARB(GL_ARRAY_BUFFER_ARB, GL_WRITE_ONLY_ARB);
 		return varray;
@@ -1414,7 +1410,7 @@ void *GPU_buffer_lock_stream(GPUBuffer *buffer)
 	if (!buffer)
 		return 0;
 
-	if (useVBOs) {
+	if (buffer->use_vbo) {
 		glBindBufferARB(GL_ARRAY_BUFFER_ARB, buffer->id);
 		/* discard previous data, avoid stalling gpu */
 		glBufferDataARB(GL_ARRAY_BUFFER_ARB, buffer->size, 0, GL_STREAM_DRAW_ARB);
@@ -1428,7 +1424,7 @@ void *GPU_buffer_lock_stream(GPUBuffer *buffer)
 
 void GPU_buffer_unlock(GPUBuffer *buffer)
 {
-	if (useVBOs) {
+	if (buffer->use_vbo) {
 		if (buffer) {
 			/* note: this operation can fail, could return
 			 * an error code from this function? */
@@ -1442,7 +1438,7 @@ void GPU_buffer_unlock(GPUBuffer *buffer)
 void GPU_buffer_draw_elements(GPUBuffer *elements, unsigned int mode, int start, int count)
 {
 	glDrawElements(mode, count, GL_UNSIGNED_INT,
-	               (useVBOs ?
+	               (elements->use_vbo ?
 	                (void *)(start * sizeof(unsigned int)) :
 	                ((int *)elements->pointer) + start));
 }