Matcap support in 3D Viewport.

Full log is here:
http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.66/Usability#Matcap_in_3D_viewport

Implementation notes:

- Matcaps are an extension of Solid draw mode, and don't show in other drawmodes.
  (It's mostly intended to aid modeling/sculpt)

- By design, Matcaps are a UI feature, and only stored locally for the UI itself, and
  won't affect rendering or materials.

- Currently a set of 16 (GPL licensed) Matcaps have been compiled into Blender. 
  It doesn't take memory or cpu time, until you use it.

- Brush Icons and Matcaps use same code now, and only get generated/allocated on
  actually using it (instead of on startup).

- The current set might get new or different images still, based on user feedback.

- Matcap images are 512x512 pixels, so each image takes 1 Mb memory. Unused matcaps get 
  freed immediately. The Matcap icon previews (128x128 pixels) stay in memory.

- Loading own matcap image files will be added later. That needs design and code work 
  to get it stable and memory-friendly.

- The GLSL code uses the ID PreviewImage for matcaps. I tested it using the existing
  Material previews, which has its limits... especially for textured previews the
  normal-mapped matcap won't look good.

8 files changed, 224 insertions, 55 deletions

diff --git a/source/blender/gpu/GPU_extensions.h b/source/blender/gpu/GPU_extensions.h
index 7eaa4084e61..66a7c917a55 100644
--- a/source/blender/gpu/GPU_extensions.h
+++ b/source/blender/gpu/GPU_extensions.h
@@ -38,7 +38,8 @@ extern "C" {
 
 struct Image;
 struct ImageUser;
-
+struct PreviewImage;
+	
 struct GPUTexture;
 typedef struct GPUTexture GPUTexture;
 
@@ -112,6 +113,8 @@ GPUTexture *GPU_texture_create_depth(int w, int h, char err_out[256]);
 GPUTexture *GPU_texture_create_vsm_shadow_map(int size, char err_out[256]);
 GPUTexture *GPU_texture_from_blender(struct Image *ima,
 	struct ImageUser *iuser, int isdata, double time, int mipmap);
+GPUTexture *GPU_texture_from_preview(struct PreviewImage *prv, int mipmap);
+
 void GPU_texture_free(GPUTexture *tex);
 
 void GPU_texture_ref(GPUTexture *tex);
diff --git a/source/blender/gpu/GPU_material.h b/source/blender/gpu/GPU_material.h
index 22cfdab6043..17d3ce3cd73 100644
--- a/source/blender/gpu/GPU_material.h
+++ b/source/blender/gpu/GPU_material.h
@@ -54,6 +54,7 @@ struct GPUNodeStack;
 struct GPUMaterial;
 struct GPUTexture;
 struct GPULamp;
+struct PreviewImage;
 
 typedef struct GPUNode GPUNode;
 typedef struct GPUNodeLink GPUNodeLink;
@@ -108,6 +109,7 @@ GPUNodeLink *GPU_attribute(int type, const char *name);
 GPUNodeLink *GPU_uniform(float *num);
 GPUNodeLink *GPU_dynamic_uniform(float *num, int dynamictype, void *data);
 GPUNodeLink *GPU_image(struct Image *ima, struct ImageUser *iuser, int isdata);
+GPUNodeLink *GPU_image_preview(struct PreviewImage *prv);
 GPUNodeLink *GPU_texture(int size, float *pixels);
 GPUNodeLink *GPU_dynamic_texture(struct GPUTexture *tex, int dynamictype, void *data);
 GPUNodeLink *GPU_builtin(GPUBuiltin builtin);
@@ -122,6 +124,7 @@ GPUBlendMode GPU_material_alpha_blend(GPUMaterial *material, float obcol[4]);
 /* High level functions to create and use GPU materials */
 
 GPUMaterial *GPU_material_from_blender(struct Scene *scene, struct Material *ma);
+GPUMaterial *GPU_material_matcap(struct Scene *scene, struct Material *ma);
 void GPU_material_free(struct Material *ma);
 
 void GPU_materials_free(void);
diff --git a/source/blender/gpu/intern/gpu_codegen.c b/source/blender/gpu/intern/gpu_codegen.c
index 4432627ee7e..b27a4be9f21 100644
--- a/source/blender/gpu/intern/gpu_codegen.c
+++ b/source/blender/gpu/intern/gpu_codegen.c
@@ -68,6 +68,9 @@ static char *glsl_material_library = NULL;
 static const char* GPU_DATATYPE_STR[17] = {"", "float", "vec2", "vec3", "vec4",
 	NULL, NULL, NULL, NULL, "mat3", NULL, NULL, NULL, NULL, NULL, NULL, "mat4"};
 
+#define LINK_IMAGE_BLENDER	1
+#define LINK_IMAGE_PREVIEW	2
+
 /* GLSL code parsing for finding function definitions.
  * These are stored in a hash for lookup when creating a material. */
 
@@ -339,7 +342,7 @@ static int codegen_input_has_texture(GPUInput *input)
 {
 	if (input->link)
 		return 0;
-	else if (input->ima)
+	else if (input->ima || input->prv)
 		return 1;
 	else
 		return input->tex != NULL;
@@ -411,6 +414,17 @@ static void codegen_set_unique_ids(ListBase *nodes)
 					else
 						input->texid = GET_INT_FROM_POINTER(BLI_ghash_lookup(bindhash, input->ima));
 				}
+				else if (input->prv) {
+					/* input is texture from preview render, assign only one texid per
+					 * buffer to avoid sampling the same texture twice */
+					if (!BLI_ghash_haskey(bindhash, input->prv)) {
+						input->texid = texid++;
+						input->bindtex = 1;
+						BLI_ghash_insert(bindhash, input->prv, SET_INT_IN_POINTER(input->texid));
+					}
+					else
+						input->texid = GET_INT_FROM_POINTER(BLI_ghash_lookup(bindhash, input->prv));
+				}
 				else {
 					if (!BLI_ghash_haskey(bindhash, input->tex)) {
 						/* input is user created texture, check tex pointer */
@@ -718,7 +732,7 @@ static void GPU_nodes_extract_dynamic_inputs(GPUPass *pass, ListBase *nodes)
 				continue;
 			}
 
-			if (input->ima || input->tex)
+			if (input->ima || input->tex || input->prv)
 				BLI_snprintf(input->shadername, sizeof(input->shadername), "samp%d", input->texid);
 			else
 				BLI_snprintf(input->shadername, sizeof(input->shadername), "unf%d", input->id);
@@ -726,7 +740,7 @@ static void GPU_nodes_extract_dynamic_inputs(GPUPass *pass, ListBase *nodes)
 			/* pass non-dynamic uniforms to opengl */
 			extract = 0;
 
-			if (input->ima || input->tex) {
+			if (input->ima || input->tex || input->prv) {
 				if (input->bindtex)
 					extract = 1;
 			}
@@ -762,11 +776,14 @@ void GPU_pass_bind(GPUPass *pass, double time, int mipmap)
 	for (input=inputs->first; input; input=input->next) {
 		if (input->ima)
 			input->tex = GPU_texture_from_blender(input->ima, input->iuser, input->image_isdata, time, mipmap);
+		else if (input->prv)
+			input->tex = GPU_texture_from_preview(input->prv, mipmap);
 
 		if (input->tex && input->bindtex) {
 			GPU_texture_bind(input->tex, input->texid);
 			GPU_shader_uniform_texture(shader, input->shaderloc, input->tex);
 		}
+			
 	}
 }
 
@@ -781,7 +798,7 @@ void GPU_pass_update_uniforms(GPUPass *pass)
 
 	/* pass dynamic inputs to opengl, others were removed */
 	for (input=inputs->first; input; input=input->next)
-		if (!(input->ima || input->tex))
+		if (!(input->ima || input->tex || input->prv))
 			GPU_shader_uniform_vector(shader, input->shaderloc, input->type, 1,
 				input->dynamicvec);
 }
@@ -799,7 +816,7 @@ void GPU_pass_unbind(GPUPass *pass)
 		if (input->tex && input->bindtex)
 			GPU_texture_unbind(input->tex);
 
-		if (input->ima)
+		if (input->ima || input->prv)
 			input->tex = NULL;
 	}
 	
@@ -915,9 +932,13 @@ static void gpu_node_input_link(GPUNode *node, GPUNodeLink *link, int type)
 		input->type = GPU_VEC4;
 		input->source = GPU_SOURCE_TEX;
 
-		input->ima = link->ptr1;
-		input->iuser = link->ptr2;
-		input->image_isdata = link->image_isdata;
+		if (link->image == LINK_IMAGE_PREVIEW)
+			input->prv = link->ptr1;
+		else {
+			input->ima = link->ptr1;
+			input->iuser = link->ptr2;
+			input->image_isdata = link->image_isdata;
+		}
 		input->textarget = GL_TEXTURE_2D;
 		input->textype = GPU_TEX2D;
 		MEM_freeN(link);
@@ -1117,7 +1138,7 @@ GPUNodeLink *GPU_image(Image *ima, ImageUser *iuser, int isdata)
 {
 	GPUNodeLink *link = GPU_node_link_create(0);
 
-	link->image= 1;
+	link->image= LINK_IMAGE_BLENDER;
 	link->ptr1= ima;
 	link->ptr2= iuser;
 	link->image_isdata= isdata;
@@ -1125,6 +1146,17 @@ GPUNodeLink *GPU_image(Image *ima, ImageUser *iuser, int isdata)
 	return link;
 }
 
+GPUNodeLink *GPU_image_preview(PreviewImage *prv)
+{
+	GPUNodeLink *link = GPU_node_link_create(0);
+	
+	link->image= LINK_IMAGE_PREVIEW;
+	link->ptr1= prv;
+	
+	return link;
+}
+
+
 GPUNodeLink *GPU_texture(int size, float *pixels)
 {
 	GPUNodeLink *link = GPU_node_link_create(0);
diff --git a/source/blender/gpu/intern/gpu_codegen.h b/source/blender/gpu/intern/gpu_codegen.h
index f61f34908c5..2e4cfe2e37c 100644
--- a/source/blender/gpu/intern/gpu_codegen.h
+++ b/source/blender/gpu/intern/gpu_codegen.h
@@ -43,6 +43,7 @@ struct GPUOutput;
 struct GPUNode;
 struct GPUVertexAttribs;
 struct GPUFrameBuffer;
+struct PreviewImage;
 
 #define MAX_FUNCTION_NAME	64
 #define MAX_PARAMETER		32
@@ -138,6 +139,7 @@ typedef struct GPUInput {
 
 	struct Image *ima;		/* image */
 	struct ImageUser *iuser;/* image user */
+	struct PreviewImage *prv;	/* preview images & icons */
 	int image_isdata;		/* image does not contain color data */
 	float *dynamicvec;		/* vector data in case it is dynamic */
 	int dynamictype;		/* origin of the dynamic uniform (GPUDynamicType) */
diff --git a/source/blender/gpu/intern/gpu_draw.c b/source/blender/gpu/intern/gpu_draw.c
index 254899e6e07..90a92dbcddc 100644
--- a/source/blender/gpu/intern/gpu_draw.c
+++ b/source/blender/gpu/intern/gpu_draw.c
@@ -664,6 +664,7 @@ int GPU_verify_image(Image *ima, ImageUser *iuser, int tftile, int compare, int
 	return *bind;
 }
 
+/* Image *ima can be NULL */
 void GPU_create_gl_tex(unsigned int *bind, unsigned int *pix, float * frect, int rectw, int recth, int mipmap, int use_high_bit_depth, Image *ima)
 {
 	unsigned int *scalerect = NULL;
@@ -723,7 +724,8 @@ void GPU_create_gl_tex(unsigned int *bind, unsigned int *pix, float * frect, int
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, gpu_get_mipmap_filter(0));
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, gpu_get_mipmap_filter(1));
 
-		ima->tpageflag |= IMA_MIPMAP_COMPLETE;
+		if (ima)
+			ima->tpageflag |= IMA_MIPMAP_COMPLETE;
 	}
 
 	if (GLEW_EXT_texture_filter_anisotropic)
@@ -1283,10 +1285,9 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 	GPUMaterial *gpumat;
 	GPUBlendMode alphablend;
 	int a;
-
 	int gamma = BKE_scene_check_color_management_enabled(scene);
-
 	int new_shading_nodes = BKE_scene_use_new_shading_nodes(scene);
+	int use_matcap = (v3d->flag2 & V3D_SHOW_SOLID_MATCAP); /* assumes v3d->defmaterial->preview is set */
 	
 	/* initialize state */
 	memset(&GMS, 0, sizeof(GMS));
@@ -1298,7 +1299,7 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 
 	GMS.gob = ob;
 	GMS.gscene = scene;
-	GMS.totmat= ob->totcol+1; /* materials start from 1, default material is 0 */
+	GMS.totmat= use_matcap? 1 : ob->totcol+1; /* materials start from 1, default material is 0 */
 	GMS.glay= (v3d->localvd)? v3d->localvd->lay: v3d->lay; /* keep lamps visible in local view */
 	GMS.gviewmat= rv3d->viewmat;
 	GMS.gviewinv= rv3d->viewinv;
@@ -1324,59 +1325,72 @@ void GPU_begin_object_materials(View3D *v3d, RegionView3D *rv3d, Scene *scene, O
 		GMS.alphablend= GMS.alphablend_fixed;
 	}
 
-	/* no materials assigned? */
-	if (ob->totcol==0) {
-		gpu_material_to_fixed(&GMS.matbuf[0], &defmaterial, 0, ob, new_shading_nodes);
-
+	/* viewport material, setup in space_view3d, defaults to matcap using ma->preview now */
+	if (use_matcap) {
+		GMS.gmatbuf[0] = v3d->defmaterial;
+		GPU_material_matcap(scene, v3d->defmaterial);
+		
 		/* do material 1 too, for displists! */
 		memcpy(&GMS.matbuf[1], &GMS.matbuf[0], sizeof(GPUMaterialFixed));
-
-		if (glsl) {
-			GMS.gmatbuf[0]= &defmaterial;
-			GPU_material_from_blender(GMS.gscene, &defmaterial);
-		}
-
+	
 		GMS.alphablend[0]= GPU_BLEND_SOLID;
 	}
+	else {
 	
-	/* setup materials */
-	for (a=1; a<=ob->totcol; a++) {
-		/* find a suitable material */
-		ma= give_current_material(ob, a);
-		if (!glsl && !new_shading_nodes) ma= gpu_active_node_material(ma);
-		if (ma==NULL) ma= &defmaterial;
-
-		/* create glsl material if requested */
-		gpumat = (glsl)? GPU_material_from_blender(GMS.gscene, ma): NULL;
-
-		if (gpumat) {
-			/* do glsl only if creating it succeed, else fallback */
-			GMS.gmatbuf[a]= ma;
-			alphablend = GPU_material_alpha_blend(gpumat, ob->col);
-		}
-		else {
-			/* fixed function opengl materials */
-			gpu_material_to_fixed(&GMS.matbuf[a], ma, gamma, ob, new_shading_nodes);
+		/* no materials assigned? */
+		if (ob->totcol==0) {
+			gpu_material_to_fixed(&GMS.matbuf[0], &defmaterial, 0, ob, new_shading_nodes);
+
+			/* do material 1 too, for displists! */
+			memcpy(&GMS.matbuf[1], &GMS.matbuf[0], sizeof(GPUMaterialFixed));
 
-			if (GMS.use_alpha_pass) {
-				GMS.matbuf[a].diff[3]= ma->alpha;
-				alphablend = (ma->alpha == 1.0f)? GPU_BLEND_SOLID: GPU_BLEND_ALPHA;
+			if (glsl) {
+				GMS.gmatbuf[0]= &defmaterial;
+				GPU_material_from_blender(GMS.gscene, &defmaterial);
+			}
+
+			GMS.alphablend[0]= GPU_BLEND_SOLID;
+		}
+		
+		/* setup materials */
+		for (a=1; a<=ob->totcol; a++) {
+			/* find a suitable material */
+			ma= give_current_material(ob, a);
+			if (!glsl && !new_shading_nodes) ma= gpu_active_node_material(ma);
+			if (ma==NULL) ma= &defmaterial;
+
+			/* create glsl material if requested */
+			gpumat = (glsl)? GPU_material_from_blender(GMS.gscene, ma): NULL;
+
+			if (gpumat) {
+				/* do glsl only if creating it succeed, else fallback */
+				GMS.gmatbuf[a]= ma;
+				alphablend = GPU_material_alpha_blend(gpumat, ob->col);
 			}
 			else {
-				GMS.matbuf[a].diff[3]= 1.0f;
-				alphablend = GPU_BLEND_SOLID;
+				/* fixed function opengl materials */
+				gpu_material_to_fixed(&GMS.matbuf[a], ma, gamma, ob, new_shading_nodes);
+
+				if (GMS.use_alpha_pass) {
+					GMS.matbuf[a].diff[3]= ma->alpha;
+					alphablend = (ma->alpha == 1.0f)? GPU_BLEND_SOLID: GPU_BLEND_ALPHA;
+				}
+				else {
+					GMS.matbuf[a].diff[3]= 1.0f;
+					alphablend = GPU_BLEND_SOLID;
+				}
 			}
-		}
 
-		/* setting 'do_alpha_after = TRUE' indicates this object needs to be
-		 * drawn in a second alpha pass for improved blending */
-		if (do_alpha_after && !GMS.is_alpha_pass)
-			if (ELEM3(alphablend, GPU_BLEND_ALPHA, GPU_BLEND_ADD, GPU_BLEND_ALPHA_SORT))
-				*do_alpha_after = TRUE;
+			/* setting 'do_alpha_after = TRUE' indicates this object needs to be
+			 * drawn in a second alpha pass for improved blending */
+			if (do_alpha_after && !GMS.is_alpha_pass)
+				if (ELEM3(alphablend, GPU_BLEND_ALPHA, GPU_BLEND_ADD, GPU_BLEND_ALPHA_SORT))
+					*do_alpha_after = TRUE;
 
-		GMS.alphablend[a]= alphablend;
+			GMS.alphablend[a]= alphablend;
+		}
 	}
-
+	
 	/* let's start with a clean state */
 	GPU_disable_material();
 }
diff --git a/source/blender/gpu/intern/gpu_extensions.c b/source/blender/gpu/intern/gpu_extensions.c
index bc859d0ec07..0ef60aaf978 100644
--- a/source/blender/gpu/intern/gpu_extensions.c
+++ b/source/blender/gpu/intern/gpu_extensions.c
@@ -539,6 +539,7 @@ GPUTexture *GPU_texture_from_blender(Image *ima, ImageUser *iuser, int isdata, d
 	glGetIntegerv(GL_TEXTURE_BINDING_2D, &lastbindcode);
 
 	GPU_update_image_time(ima, time);
+	/* this binds a texture, so that's why to restore it with lastbindcode */
 	bindcode = GPU_verify_image(ima, iuser, 0, 0, mipmap, isdata);
 
 	if (ima->gputexture) {
@@ -579,6 +580,59 @@ GPUTexture *GPU_texture_from_blender(Image *ima, ImageUser *iuser, int isdata, d
 	return tex;
 }
 
+GPUTexture *GPU_texture_from_preview(PreviewImage *prv, int mipmap)
+{
+	GPUTexture *tex = prv->gputexture[0];
+	GLint w, h, lastbindcode;
+	GLuint bindcode = 0;
+	
+	glGetIntegerv(GL_TEXTURE_BINDING_2D, &lastbindcode);
+	
+	if (tex)
+		bindcode = tex->bindcode;
+	
+	/* this binds a texture, so that's why to restore it */
+	if (bindcode == 0) {
+		GPU_create_gl_tex(&bindcode, prv->rect[0], NULL, prv->w[0], prv->h[0], mipmap, 0, NULL);
+	}
+	if (tex) {
+		tex->bindcode = bindcode;
+		glBindTexture(GL_TEXTURE_2D, lastbindcode);
+		return tex;
+	}
+
+	/* error binding anything */
+	if (!bindcode) {
+		glBindTexture(GL_TEXTURE_2D, lastbindcode);
+		return NULL;
+	}
+	
+	tex = MEM_callocN(sizeof(GPUTexture), "GPUTexture");
+	tex->bindcode = bindcode;
+	tex->number = -1;
+	tex->refcount = 1;
+	tex->target = GL_TEXTURE_2D;
+	
+	prv->gputexture[0]= tex;
+	
+	if (!glIsTexture(tex->bindcode)) {
+		GPU_print_error("Blender Texture");
+	}
+	else {
+		glBindTexture(GL_TEXTURE_2D, tex->bindcode);
+		glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &w);
+		glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, &h);
+		
+		tex->w = w;
+		tex->h = h;
+	}
+	
+	glBindTexture(GL_TEXTURE_2D, lastbindcode);
+	
+	return tex;
+
+}
+
 GPUTexture *GPU_texture_create_1D(int w, float *fpixels, char err_out[256])
 {
 	GPUTexture *tex = GPU_texture_create_nD(w, 1, 1, fpixels, 0, err_out);
diff --git a/source/blender/gpu/intern/gpu_material.c b/source/blender/gpu/intern/gpu_material.c
index f6403e9359d..9731d7a6b3a 100644
--- a/source/blender/gpu/intern/gpu_material.c
+++ b/source/blender/gpu/intern/gpu_material.c
@@ -1506,6 +1506,52 @@ static GPUNodeLink *gpu_material_diffuse_bsdf(GPUMaterial *mat, Material *ma)
 	return outlink;
 }
 
+static GPUNodeLink *gpu_material_preview_matcap(GPUMaterial *mat, Material *ma)
+{
+	GPUNodeLink *outlink;
+	
+	GPU_link(mat, "material_preview_matcap", GPU_uniform(&ma->r), GPU_image_preview(ma->preview), GPU_builtin(GPU_VIEW_NORMAL), &outlink);
+	
+	return outlink;
+}
+
+/* new solid draw mode with glsl matcaps */
+GPUMaterial *GPU_material_matcap(Scene *scene, Material *ma)
+{
+	GPUMaterial *mat;
+	GPUNodeLink *outlink;
+	LinkData *link;
+	
+	for (link=ma->gpumaterial.first; link; link=link->next)
+		if (((GPUMaterial*)link->data)->scene == scene)
+			return link->data;
+	
+	/* allocate material */
+	mat = GPU_material_construct_begin(ma);
+	mat->scene = scene;
+	
+	if (ma->preview && ma->preview->rect[0]) {
+		outlink = gpu_material_preview_matcap(mat, ma);
+	}
+	else {
+		outlink = gpu_material_diffuse_bsdf(mat, ma);
+	}
+		
+	GPU_material_output_link(mat, outlink);
+
+	GPU_material_construct_end(mat);
+	
+	/* note that even if building the shader fails in some way, we still keep
+	 * it to avoid trying to compile again and again, and simple do not use
+	 * the actual shader on drawing */
+	
+	link = MEM_callocN(sizeof(LinkData), "GPUMaterialLink");
+	link->data = mat;
+	BLI_addtail(&ma->gpumaterial, link);
+	
+	return mat;
+}
+
 GPUMaterial *GPU_material_from_blender(Scene *scene, Material *ma)
 {
 	GPUMaterial *mat;
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index e89be91c89a..45e7831d20d 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -2256,3 +2256,18 @@ void node_output_material(vec4 surface, vec4 volume, float displacement, out vec
 	result = surface;
 }
 
+/* ********************** matcap style render ******************** */
+
+void material_preview_matcap(vec4 color, sampler2D ima, vec3 N, out vec4 result)
+{
+	vec2 tex;
+
+	if (N.z < 0.0) {
+		N.z = 0.0;
+		N = normalize(N);
+	}
+
+	tex.x = 0.5 + 0.49 * N.x;
+	tex.y = 0.5 + 0.49 * N.y;
+	result = texture2D(ima, tex);
+}