blender-archive/source/blender/editors/sculpt_paint/paint_cursor.c

/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software  Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2009 by Nicholas Bishop
 * All rights reserved.
 *
 * Contributor(s): Jason Wilkins, Tom Musgrove.
 *
 * ***** END GPL LICENSE BLOCK *****
 *
 */

/** \file blender/editors/sculpt_paint/paint_cursor.c
 *  \ingroup edsculpt
 */

#include "MEM_guardedalloc.h"

#include "BLI_math.h"
#include "BLI_rect.h"
#include "BLI_task.h"
#include "BLI_utildefines.h"

#include "DNA_brush_types.h"
#include "DNA_customdata_types.h"
#include "DNA_color_types.h"
#include "DNA_object_types.h"
#include "DNA_scene_types.h"
#include "DNA_screen_types.h"
#include "DNA_space_types.h"
#include "DNA_userdef_types.h"
#include "DNA_view3d_types.h"

#include "BKE_brush.h"
#include "BKE_context.h"
#include "BKE_curve.h"
#include "BKE_image.h"
#include "BKE_node.h"
#include "BKE_paint.h"
#include "BKE_colortools.h"

#include "WM_api.h"

#include "IMB_imbuf_types.h"

#include "ED_view3d.h"

#include "GPU_draw.h"
#include "GPU_immediate.h"
#include "GPU_immediate_util.h"
#include "GPU_matrix.h"
#include "GPU_state.h"

#include "UI_resources.h"

#include "paint_intern.h"
/* still needed for sculpt_stroke_get_location, should be
 * removed eventually (TODO) */
#include "sculpt_intern.h"

/* TODOs:
 *
 * Some of the cursor drawing code is doing non-draw stuff
 * (e.g. updating the brush rake angle). This should be cleaned up
 * still.
 *
 * There is also some ugliness with sculpt-specific code.
 */

typedef struct TexSnapshot {
	GLuint overlay_texture;
	int winx;
	int winy;
	int old_size;
	float old_zoom;
	bool old_col;
} TexSnapshot;

typedef struct CursorSnapshot {
	GLuint overlay_texture;
	int size;
	int zoom;
} CursorSnapshot;

static TexSnapshot primary_snap = {0};
static TexSnapshot secondary_snap  = {0};
static CursorSnapshot cursor_snap  = {0};

/* delete overlay cursor textures to preserve memory and invalidate all overlay flags */
void paint_cursor_delete_textures(void)
{
	if (primary_snap.overlay_texture)
		glDeleteTextures(1, &primary_snap.overlay_texture);
	if (secondary_snap.overlay_texture)
		glDeleteTextures(1, &secondary_snap.overlay_texture);
	if (cursor_snap.overlay_texture)
		glDeleteTextures(1, &cursor_snap.overlay_texture);

	memset(&primary_snap, 0, sizeof(TexSnapshot));
	memset(&secondary_snap, 0, sizeof(TexSnapshot));
	memset(&cursor_snap, 0, sizeof(CursorSnapshot));

	BKE_paint_invalidate_overlay_all();
}

static int same_tex_snap(TexSnapshot *snap, MTex *mtex, ViewContext *vc, bool col, float zoom)
{
	return (/* make brush smaller shouldn't cause a resample */
	        //(mtex->brush_map_mode != MTEX_MAP_MODE_VIEW ||
	        //(BKE_brush_size_get(vc->scene, brush) <= snap->BKE_brush_size_get)) &&

	        (mtex->brush_map_mode != MTEX_MAP_MODE_TILED ||
	         (vc->ar->winx == snap->winx &&
	          vc->ar->winy == snap->winy)) &&
	        (mtex->brush_map_mode == MTEX_MAP_MODE_STENCIL ||
	        snap->old_zoom == zoom) &&
	        snap->old_col == col
	        );
}

static void make_tex_snap(TexSnapshot *snap, ViewContext *vc, float zoom)
{
	snap->old_zoom = zoom;
	snap->winx = vc->ar->winx;
	snap->winy = vc->ar->winy;
}

typedef struct LoadTexData {
	Brush *br;
	ViewContext *vc;

	MTex *mtex;
	GLubyte *buffer;
	bool col;

	struct ImagePool *pool;
	int size;
	float rotation;
	float radius;
} LoadTexData;

static void load_tex_task_cb_ex(
        void *__restrict userdata,
        const int j,
        const ParallelRangeTLS *__restrict tls)
{
	LoadTexData *data = userdata;
	Brush *br = data->br;
	ViewContext *vc = data->vc;

	MTex *mtex = data->mtex;
	GLubyte *buffer = data->buffer;
	const bool col = data->col;

	struct ImagePool *pool = data->pool;
	const int size = data->size;
	const float rotation = data->rotation;
	const float radius = data->radius;

	bool convert_to_linear = false;
	struct ColorSpace *colorspace = NULL;

	if (mtex->tex && mtex->tex->type == TEX_IMAGE && mtex->tex->ima) {
		ImBuf *tex_ibuf = BKE_image_pool_acquire_ibuf(mtex->tex->ima, &mtex->tex->iuser, pool);
		/* For consistency, sampling always returns color in linear space */
		if (tex_ibuf && tex_ibuf->rect_float == NULL) {
			convert_to_linear = true;
			colorspace = tex_ibuf->rect_colorspace;
		}
		BKE_image_pool_release_ibuf(mtex->tex->ima, tex_ibuf, pool);
	}

	for (int i = 0; i < size; i++) {
		// largely duplicated from tex_strength

		int index = j * size + i;

		float x = (float)i / size;
		float y = (float)j / size;
		float len;

		if (mtex->brush_map_mode == MTEX_MAP_MODE_TILED) {
			x *= vc->ar->winx / radius;
			y *= vc->ar->winy / radius;
		}
		else {
			x = (x - 0.5f) * 2.0f;
			y = (y - 0.5f) * 2.0f;
		}

		len = sqrtf(x * x + y * y);

		if (ELEM(mtex->brush_map_mode, MTEX_MAP_MODE_TILED, MTEX_MAP_MODE_STENCIL) || len <= 1.0f) {
			/* it is probably worth optimizing for those cases where the texture is not rotated by skipping the calls to
			 * atan2, sqrtf, sin, and cos. */
			if (mtex->tex && (rotation > 0.001f || rotation < -0.001f)) {
				const float angle = atan2f(y, x) + rotation;

				x = len * cosf(angle);
				y = len * sinf(angle);
			}

			if (col) {
				float rgba[4];

				paint_get_tex_pixel_col(mtex, x, y, rgba, pool, tls->thread_id, convert_to_linear, colorspace);

				buffer[index * 4]     = rgba[0] * 255;
				buffer[index * 4 + 1] = rgba[1] * 255;
				buffer[index * 4 + 2] = rgba[2] * 255;
				buffer[index * 4 + 3] = rgba[3] * 255;
			}
			else {
				float avg = paint_get_tex_pixel(mtex, x, y, pool, tls->thread_id);

				avg += br->texture_sample_bias;

				/* clamp to avoid precision overflow */
				CLAMP(avg, 0.0f, 1.0f);
				buffer[index] = 255 - (GLubyte)(255 * avg);
			}
		}
		else {
			if (col) {
				buffer[index * 4]     = 0;
				buffer[index * 4 + 1] = 0;
				buffer[index * 4 + 2] = 0;
				buffer[index * 4 + 3] = 0;
			}
			else {
				buffer[index] = 0;
			}
		}
	}
}

static int load_tex(Brush *br, ViewContext *vc, float zoom, bool col, bool primary)
{
	bool init;
	TexSnapshot *target;

	MTex *mtex = (primary) ? &br->mtex : &br->mask_mtex;
	eOverlayControlFlags overlay_flags = BKE_paint_get_overlay_flags();
	GLubyte *buffer = NULL;

	int size;
	bool refresh;
	eOverlayControlFlags invalid = (
	        (primary) ?
	        (overlay_flags & PAINT_OVERLAY_INVALID_TEXTURE_PRIMARY) :
	        (overlay_flags & PAINT_OVERLAY_INVALID_TEXTURE_SECONDARY));
	target = (primary) ? &primary_snap : &secondary_snap;

	refresh =
	    !target->overlay_texture ||
	    (invalid != 0) ||
	    !same_tex_snap(target, mtex, vc, col, zoom);

	init = (target->overlay_texture != 0);

	if (refresh) {
		struct ImagePool *pool = NULL;
		/* stencil is rotated later */
		const float rotation = (mtex->brush_map_mode != MTEX_MAP_MODE_STENCIL) ? -mtex->rot : 0.0f;
		const float radius = BKE_brush_size_get(vc->scene, br) * zoom;

		make_tex_snap(target, vc, zoom);

		if (mtex->brush_map_mode == MTEX_MAP_MODE_VIEW) {
			int s = BKE_brush_size_get(vc->scene, br);
			int r = 1;

			for (s >>= 1; s > 0; s >>= 1)
				r++;

			size = (1 << r);

			if (size < 256)
				size = 256;

			if (size < target->old_size)
				size = target->old_size;
		}
		else {
			size = 512;
		}

		if (target->old_size != size) {
			if (target->overlay_texture) {
				glDeleteTextures(1, &target->overlay_texture);
				target->overlay_texture = 0;
			}

			init = false;

			target->old_size = size;
		}
		if (col)
			buffer = MEM_mallocN(sizeof(GLubyte) * size * size * 4, "load_tex");
		else
			buffer = MEM_mallocN(sizeof(GLubyte) * size * size, "load_tex");

		pool = BKE_image_pool_new();

		if (mtex->tex && mtex->tex->nodetree) {
			/* has internal flag to detect it only does it once */
			ntreeTexBeginExecTree(mtex->tex->nodetree);
		}

		LoadTexData data = {
		    .br = br, .vc = vc, .mtex = mtex, .buffer = buffer, .col = col,
		    .pool = pool, .size = size, .rotation = rotation, .radius = radius,
		};

		ParallelRangeSettings settings;
		BLI_parallel_range_settings_defaults(&settings);
		BLI_task_parallel_range(0, size, &data, load_tex_task_cb_ex, &settings);

		if (mtex->tex && mtex->tex->nodetree)
			ntreeTexEndExecTree(mtex->tex->nodetree->execdata);

		if (pool)
			BKE_image_pool_free(pool);

		if (!target->overlay_texture)
			glGenTextures(1, &target->overlay_texture);
	}
	else {
		size = target->old_size;
	}

	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, target->overlay_texture);

	if (refresh) {
		GLenum format = col ? GL_RGBA : GL_RED;
		GLenum internalformat = col ? GL_RGBA8 : GL_R8;

		if (!init || (target->old_col != col)) {
			glTexImage2D(GL_TEXTURE_2D, 0, internalformat, size, size, 0, format, GL_UNSIGNED_BYTE, buffer);
		}
		else {
			glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, size, size, format, GL_UNSIGNED_BYTE, buffer);
		}

		if (buffer)
			MEM_freeN(buffer);

		target->old_col = col;
	}

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	if (mtex->brush_map_mode == MTEX_MAP_MODE_VIEW) {
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
	}

	BKE_paint_reset_overlay_invalid(invalid);

	return 1;
}

static void load_tex_cursor_task_cb(
        void *__restrict userdata,
        const int j,
        const ParallelRangeTLS *__restrict UNUSED(tls))
{
	LoadTexData *data = userdata;
	Brush *br = data->br;

	GLubyte *buffer = data->buffer;

	const int size = data->size;

	for (int i = 0; i < size; i++) {
		// largely duplicated from tex_strength

		const int index = j * size + i;
		const float x = (((float)i / size) - 0.5f) * 2.0f;
		const float y = (((float)j / size) - 0.5f) * 2.0f;
		const float len = sqrtf(x * x + y * y);

		if (len <= 1.0f) {
			float avg = BKE_brush_curve_strength_clamped(br, len, 1.0f);  /* Falloff curve */

			buffer[index] = 255 - (GLubyte)(255 * avg);
		}
		else {
			buffer[index] = 0;
		}
	}
}

static int load_tex_cursor(Brush *br, ViewContext *vc, float zoom)
{
	bool init;

	eOverlayControlFlags overlay_flags = BKE_paint_get_overlay_flags();
	GLubyte *buffer = NULL;

	int size;
	const bool refresh =
	    !cursor_snap.overlay_texture ||
	    (overlay_flags & PAINT_OVERLAY_INVALID_CURVE) ||
	    cursor_snap.zoom != zoom;

	init = (cursor_snap.overlay_texture != 0);

	if (refresh) {
		int s, r;

		cursor_snap.zoom = zoom;

		s = BKE_brush_size_get(vc->scene, br);
		r = 1;

		for (s >>= 1; s > 0; s >>= 1)
			r++;

		size = (1 << r);

		if (size < 256)
			size = 256;

		if (size < cursor_snap.size)
			size = cursor_snap.size;

		if (cursor_snap.size != size) {
			if (cursor_snap.overlay_texture) {
				glDeleteTextures(1, &cursor_snap.overlay_texture);
				cursor_snap.overlay_texture = 0;
			}

			init = false;

			cursor_snap.size = size;
		}
		buffer = MEM_mallocN(sizeof(GLubyte) * size * size, "load_tex");

		curvemapping_initialize(br->curve);

		LoadTexData data = {
		    .br = br, .buffer = buffer, .size = size,
		};

		ParallelRangeSettings settings;
		BLI_parallel_range_settings_defaults(&settings);
		BLI_task_parallel_range(0, size, &data, load_tex_cursor_task_cb, &settings);

		if (!cursor_snap.overlay_texture)
			glGenTextures(1, &cursor_snap.overlay_texture);
	}
	else {
		size = cursor_snap.size;
	}

	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, cursor_snap.overlay_texture);

	if (refresh) {
		if (!init) {
			glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, size, size, 0, GL_RED, GL_UNSIGNED_BYTE, buffer);
		}
		else {
			glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, size, size, GL_RED, GL_UNSIGNED_BYTE, buffer);
		}

		if (buffer)
			MEM_freeN(buffer);
	}

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);

	BKE_paint_reset_overlay_invalid(PAINT_OVERLAY_INVALID_CURVE);

	return 1;
}



static int project_brush_radius(
        ViewContext *vc,
        float radius,
        const float location[3])
{
	float view[3], nonortho[3], ortho[3], offset[3], p1[2], p2[2];

	ED_view3d_global_to_vector(vc->rv3d, location, view);

	/* create a vector that is not orthogonal to view */

	if (fabsf(view[0]) < 0.1f) {
		nonortho[0] = view[0] + 1.0f;
		nonortho[1] = view[1];
		nonortho[2] = view[2];
	}
	else if (fabsf(view[1]) < 0.1f) {
		nonortho[0] = view[0];
		nonortho[1] = view[1] + 1.0f;
		nonortho[2] = view[2];
	}
	else {
		nonortho[0] = view[0];
		nonortho[1] = view[1];
		nonortho[2] = view[2] + 1.0f;
	}

	/* get a vector in the plane of the view */
	cross_v3_v3v3(ortho, nonortho, view);
	normalize_v3(ortho);

	/* make a point on the surface of the brush tangent to the view */
	mul_v3_fl(ortho, radius);
	add_v3_v3v3(offset, location, ortho);

	/* project the center of the brush, and the tangent point to the view onto the screen */
	if ((ED_view3d_project_float_global(vc->ar, location, p1, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK) &&
	    (ED_view3d_project_float_global(vc->ar, offset,   p2, V3D_PROJ_TEST_NOP) == V3D_PROJ_RET_OK))
	{
		/* the distance between these points is the size of the projected brush in pixels */
		return len_v2v2(p1, p2);
	}
	else {
		BLI_assert(0);  /* assert because the code that sets up the vectors should disallow this */
		return 0;
	}
}

static bool sculpt_get_brush_geometry(
        bContext *C, ViewContext *vc,
        int x, int y, int *pixel_radius,
        float location[3], UnifiedPaintSettings *ups)
{
	Scene *scene = CTX_data_scene(C);
	Paint *paint = BKE_paint_get_active_from_context(C);
	float mouse[2];
	bool hit = false;

	mouse[0] = x;
	mouse[1] = y;

	if (vc->obact->sculpt && vc->obact->sculpt->pbvh) {
		if (!ups->stroke_active) {
			hit = sculpt_stroke_get_location(C, location, mouse);
		}
		else {
			hit = ups->last_hit;
			copy_v3_v3(location, ups->last_location);
		}
	}

	if (hit) {
		Brush *brush = BKE_paint_brush(paint);

		*pixel_radius = project_brush_radius(
		        vc, BKE_brush_unprojected_radius_get(scene, brush), location);

		if (*pixel_radius == 0)
			*pixel_radius = BKE_brush_size_get(scene, brush);

		mul_m4_v3(vc->obact->obmat, location);
	}
	else {
		Sculpt *sd    = CTX_data_tool_settings(C)->sculpt;
		Brush *brush = BKE_paint_brush(&sd->paint);

		*pixel_radius = BKE_brush_size_get(scene, brush);
	}

	return hit;
}

/* Draw an overlay that shows what effect the brush's texture will
 * have on brush strength */
static void paint_draw_tex_overlay(
        UnifiedPaintSettings *ups, Brush *brush,
        ViewContext *vc, int x, int y, float zoom, bool col, bool primary)
{
	rctf quad;
	/* check for overlay mode */

	MTex *mtex = (primary) ? &brush->mtex : &brush->mask_mtex;
	bool valid = (
	        (primary) ?
	        (brush->overlay_flags & BRUSH_OVERLAY_PRIMARY) != 0 :
	        (brush->overlay_flags & BRUSH_OVERLAY_SECONDARY) != 0);
	int overlay_alpha = (primary) ? brush->texture_overlay_alpha : brush->mask_overlay_alpha;

	if (!(mtex->tex) || !((mtex->brush_map_mode == MTEX_MAP_MODE_STENCIL) ||
	    (valid &&
	    ELEM(mtex->brush_map_mode, MTEX_MAP_MODE_VIEW, MTEX_MAP_MODE_TILED))))
	{
		return;
	}

	if (load_tex(brush, vc, zoom, col, primary)) {
		GPU_blend(true);

		glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
		glDepthMask(GL_FALSE);
		glDepthFunc(GL_ALWAYS);

		if (mtex->brush_map_mode == MTEX_MAP_MODE_VIEW) {
			GPU_matrix_push();

			/* brush rotation */
			GPU_matrix_translate_2f(x, y);
			GPU_matrix_rotate_2d(-RAD2DEGF(primary ? ups->brush_rotation : ups->brush_rotation_sec));
			GPU_matrix_translate_2f(-x, -y);

			/* scale based on tablet pressure */
			if (primary && ups->stroke_active && BKE_brush_use_size_pressure(vc->scene, brush)) {
				const float scale = ups->size_pressure_value;
				GPU_matrix_translate_2f(x, y);
				GPU_matrix_scale_2f(scale, scale);
				GPU_matrix_translate_2f(-x, -y);
			}

			if (ups->draw_anchored) {
				quad.xmin = ups->anchored_initial_mouse[0] - ups->anchored_size;
				quad.ymin = ups->anchored_initial_mouse[1] - ups->anchored_size;
				quad.xmax = ups->anchored_initial_mouse[0] + ups->anchored_size;
				quad.ymax = ups->anchored_initial_mouse[1] + ups->anchored_size;
			}
			else {
				const int radius = BKE_brush_size_get(vc->scene, brush) * zoom;
				quad.xmin = x - radius;
				quad.ymin = y - radius;
				quad.xmax = x + radius;
				quad.ymax = y + radius;
			}
		}
		else if (mtex->brush_map_mode == MTEX_MAP_MODE_TILED) {
			quad.xmin = 0;
			quad.ymin = 0;
			quad.xmax = BLI_rcti_size_x(&vc->ar->winrct);
			quad.ymax = BLI_rcti_size_y(&vc->ar->winrct);
		}
		/* Stencil code goes here */
		else {
			if (primary) {
				quad.xmin = -brush->stencil_dimension[0];
				quad.ymin = -brush->stencil_dimension[1];
				quad.xmax = brush->stencil_dimension[0];
				quad.ymax = brush->stencil_dimension[1];
			}
			else {
				quad.xmin = -brush->mask_stencil_dimension[0];
				quad.ymin = -brush->mask_stencil_dimension[1];
				quad.xmax = brush->mask_stencil_dimension[0];
				quad.ymax = brush->mask_stencil_dimension[1];
			}
			GPU_matrix_push();
			if (primary)
				GPU_matrix_translate_2fv(brush->stencil_pos);
			else
				GPU_matrix_translate_2fv(brush->mask_stencil_pos);
			GPU_matrix_rotate_2d(RAD2DEGF(mtex->rot));
		}

		/* set quad color. Colored overlay does not get blending */
		GPUVertFormat *format = immVertexFormat();
		uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
		uint texCoord = GPU_vertformat_attr_add(format, "texCoord", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);

		if (col) {
			immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_COLOR);
			immUniformColor4f(1.0f, 1.0f, 1.0f, overlay_alpha * 0.01f);
		}
		else {
			GPU_blend_set_func(GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
			immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_ALPHA_COLOR);
			immUniformColor3fvAlpha(U.sculpt_paint_overlay_col, overlay_alpha * 0.01f);
		}

		/* draw textured quad */
		immUniform1i("image", 0);

		immBegin(GPU_PRIM_TRI_FAN, 4);
		immAttr2f(texCoord, 0.0f, 0.0f);
		immVertex2f(pos, quad.xmin, quad.ymin);
		immAttr2f(texCoord, 1.0f, 0.0f);
		immVertex2f(pos, quad.xmax, quad.ymin);
		immAttr2f(texCoord, 1.0f, 1.0f);
		immVertex2f(pos, quad.xmax, quad.ymax);
		immAttr2f(texCoord, 0.0f, 1.0f);
		immVertex2f(pos, quad.xmin, quad.ymax);
		immEnd();

		immUnbindProgram();
		GPU_blend_set_func(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA);

		if (ELEM(mtex->brush_map_mode, MTEX_MAP_MODE_STENCIL, MTEX_MAP_MODE_VIEW)) {
			GPU_matrix_pop();
		}
	}
}

/* Draw an overlay that shows what effect the brush's texture will
 * have on brush strength */
static void paint_draw_cursor_overlay(
        UnifiedPaintSettings *ups, Brush *brush,
        ViewContext *vc, int x, int y, float zoom)
{
	rctf quad;
	/* check for overlay mode */

	if (!(brush->overlay_flags & BRUSH_OVERLAY_CURSOR)) {
		return;
	}

	if (load_tex_cursor(brush, vc, zoom)) {
		bool do_pop = false;
		float center[2];
		GPU_blend(true);

		glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
		glDepthMask(GL_FALSE);
		glDepthFunc(GL_ALWAYS);

		if (ups->draw_anchored) {
			copy_v2_v2(center, ups->anchored_initial_mouse);
			quad.xmin = ups->anchored_initial_mouse[0] - ups->anchored_size;
			quad.ymin = ups->anchored_initial_mouse[1] - ups->anchored_size;
			quad.xmax = ups->anchored_initial_mouse[0] + ups->anchored_size;
			quad.ymax = ups->anchored_initial_mouse[1] + ups->anchored_size;
		}
		else {
			const int radius = BKE_brush_size_get(vc->scene, brush) * zoom;
			center[0] = x;
			center[1] = y;

			quad.xmin = x - radius;
			quad.ymin = y - radius;
			quad.xmax = x + radius;
			quad.ymax = y + radius;
		}

		/* scale based on tablet pressure */
		if (ups->stroke_active && BKE_brush_use_size_pressure(vc->scene, brush)) {
			do_pop = true;
			GPU_matrix_push();
			GPU_matrix_translate_2fv(center);
			GPU_matrix_scale_1f(ups->size_pressure_value);
			GPU_matrix_translate_2f(-center[0], -center[1]);
		}

		GPUVertFormat *format = immVertexFormat();
		uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
		uint texCoord = GPU_vertformat_attr_add(format, "texCoord", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);

		GPU_blend_set_func(GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
		immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_ALPHA_COLOR);

		immUniformColor3fvAlpha(U.sculpt_paint_overlay_col, brush->cursor_overlay_alpha * 0.01f);

		/* draw textured quad */

		/* draw textured quad */
		immUniform1i("image", 0);

		immBegin(GPU_PRIM_TRI_FAN, 4);
		immAttr2f(texCoord, 0.0f, 0.0f);
		immVertex2f(pos, quad.xmin, quad.ymin);
		immAttr2f(texCoord, 1.0f, 0.0f);
		immVertex2f(pos, quad.xmax, quad.ymin);
		immAttr2f(texCoord, 1.0f, 1.0f);
		immVertex2f(pos, quad.xmax, quad.ymax);
		immAttr2f(texCoord, 0.0f, 1.0f);
		immVertex2f(pos, quad.xmin, quad.ymax);
		immEnd();

		immUnbindProgram();

		GPU_blend_set_func(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA);

		if (do_pop)
			GPU_matrix_pop();
	}
}

static void paint_draw_alpha_overlay(
        UnifiedPaintSettings *ups, Brush *brush,
        ViewContext *vc, int x, int y, float zoom, ePaintMode mode)
{
	/* color means that primary brush texture is colured and
	 * secondary is used for alpha/mask control */
	bool col = ELEM(mode, PAINT_MODE_TEXTURE_3D, PAINT_MODE_TEXTURE_2D, PAINT_MODE_VERTEX) ? true : false;
	eOverlayControlFlags flags = BKE_paint_get_overlay_flags();
	gpuPushAttrib(GPU_DEPTH_BUFFER_BIT | GPU_BLEND_BIT);

	/* Translate to region. */
	GPU_matrix_push();
	GPU_matrix_translate_2f(vc->ar->winrct.xmin, vc->ar->winrct.ymin);
	x -= vc->ar->winrct.xmin;
	y -= vc->ar->winrct.ymin;

	/* coloured overlay should be drawn separately */
	if (col) {
		if (!(flags & PAINT_OVERLAY_OVERRIDE_PRIMARY))
			paint_draw_tex_overlay(ups, brush, vc, x, y, zoom, true, true);
		if (!(flags & PAINT_OVERLAY_OVERRIDE_SECONDARY))
			paint_draw_tex_overlay(ups, brush, vc, x, y, zoom, false, false);
		if (!(flags & PAINT_OVERLAY_OVERRIDE_CURSOR))
			paint_draw_cursor_overlay(ups, brush, vc, x, y, zoom);
	}
	else {
		if (!(flags & PAINT_OVERLAY_OVERRIDE_PRIMARY) && (mode != PAINT_MODE_WEIGHT))
			paint_draw_tex_overlay(ups, brush, vc, x, y, zoom, false, true);
		if (!(flags & PAINT_OVERLAY_OVERRIDE_CURSOR))
			paint_draw_cursor_overlay(ups, brush, vc, x, y, zoom);
	}

	GPU_matrix_pop();
	gpuPopAttrib();
}


BLI_INLINE void draw_tri_point(
        unsigned int pos, float sel_col[4], float pivot_col[4],
        float *co, float width, bool selected)
{
	immUniformColor4fv(selected ? sel_col : pivot_col);

	GPU_line_width(3.0f);

	float w = width / 2.0f;
	float tri[3][2] = {
		{co[0], co[1] + w},
		{co[0] - w, co[1] - w},
		{co[0] + w, co[1] - w},
	};

	immBegin(GPU_PRIM_LINE_LOOP, 3);
	immVertex2fv(pos, tri[0]);
	immVertex2fv(pos, tri[1]);
	immVertex2fv(pos, tri[2]);
	immEnd();

	immUniformColor4f(1.0f, 1.0f, 1.0f, 0.5f);
	GPU_line_width(1.0f);

	immBegin(GPU_PRIM_LINE_LOOP, 3);
	immVertex2fv(pos, tri[0]);
	immVertex2fv(pos, tri[1]);
	immVertex2fv(pos, tri[2]);
	immEnd();
}

BLI_INLINE void draw_rect_point(
        unsigned int pos, float sel_col[4], float handle_col[4],
        float *co, float width, bool selected)
{
	immUniformColor4fv(selected ? sel_col : handle_col);

	GPU_line_width(3.0f);

	float w = width / 2.0f;
	float minx = co[0] - w;
	float miny = co[1] - w;
	float maxx = co[0] + w;
	float maxy = co[1] + w;

	imm_draw_box_wire_2d(pos, minx, miny, maxx, maxy);

	immUniformColor4f(1.0f, 1.0f, 1.0f, 0.5f);
	GPU_line_width(1.0f);

	imm_draw_box_wire_2d(pos, minx, miny, maxx, maxy);
}


BLI_INLINE void draw_bezier_handle_lines(unsigned int pos, float sel_col[4], BezTriple *bez)
{
	immUniformColor4f(0.0f, 0.0f, 0.0f, 0.5f);
	GPU_line_width(3.0f);

	immBegin(GPU_PRIM_LINE_STRIP, 3);
	immVertex2fv(pos, bez->vec[0]);
	immVertex2fv(pos, bez->vec[1]);
	immVertex2fv(pos, bez->vec[2]);
	immEnd();

	GPU_line_width(1.0f);

	if (bez->f1 || bez->f2) {
		immUniformColor4fv(sel_col);
	}
	else {
		immUniformColor4f(1.0f, 1.0f, 1.0f, 0.5f);
	}
	immBegin(GPU_PRIM_LINES, 2);
	immVertex2fv(pos, bez->vec[0]);
	immVertex2fv(pos, bez->vec[1]);
	immEnd();

	if (bez->f3 || bez->f2) {
		immUniformColor4fv(sel_col);
	}
	else {
		immUniformColor4f(1.0f, 1.0f, 1.0f, 0.5f);
	}
	immBegin(GPU_PRIM_LINES, 2);
	immVertex2fv(pos, bez->vec[1]);
	immVertex2fv(pos, bez->vec[2]);
	immEnd();
}

static void paint_draw_curve_cursor(Brush *brush, ViewContext *vc)
{
	GPU_matrix_push();
	GPU_matrix_translate_2f(vc->ar->winrct.xmin, vc->ar->winrct.ymin);

	if (brush->paint_curve && brush->paint_curve->points) {
		int i;
		PaintCurve *pc = brush->paint_curve;
		PaintCurvePoint *cp = pc->points;

		GPU_line_smooth(true);
		GPU_blend(true);

		/* draw the bezier handles and the curve segment between the current and next point */
		uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);

		immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

		float selec_col[4], handle_col[4], pivot_col[4];
		UI_GetThemeColor4fv(TH_VERTEX_SELECT, selec_col);
		UI_GetThemeColor4fv(TH_PAINT_CURVE_HANDLE, handle_col);
		UI_GetThemeColor4fv(TH_PAINT_CURVE_PIVOT, pivot_col);

		for (i = 0; i < pc->tot_points - 1; i++, cp++) {
			int j;
			PaintCurvePoint *cp_next = cp + 1;
			float data[(PAINT_CURVE_NUM_SEGMENTS + 1) * 2];
			/* use color coding to distinguish handles vs curve segments  */
			draw_bezier_handle_lines(pos, selec_col, &cp->bez);
			draw_tri_point(pos, selec_col, pivot_col, &cp->bez.vec[1][0], 10.0f, cp->bez.f2);
			draw_rect_point(pos, selec_col, handle_col, &cp->bez.vec[0][0], 8.0f, cp->bez.f1 || cp->bez.f2);
			draw_rect_point(pos, selec_col, handle_col, &cp->bez.vec[2][0], 8.0f, cp->bez.f3 || cp->bez.f2);

			for (j = 0; j < 2; j++)
				BKE_curve_forward_diff_bezier(
				        cp->bez.vec[1][j],
				        cp->bez.vec[2][j],
				        cp_next->bez.vec[0][j],
				        cp_next->bez.vec[1][j],
				        data + j, PAINT_CURVE_NUM_SEGMENTS, sizeof(float[2]));

			float (*v)[2] = (float(*)[2])data;

			immUniformColor4f(0.0f, 0.0f, 0.0f, 0.5f);
			GPU_line_width(3.0f);
			immBegin(GPU_PRIM_LINE_STRIP, PAINT_CURVE_NUM_SEGMENTS + 1);
			for (j = 0; j <= PAINT_CURVE_NUM_SEGMENTS; j++) {
				immVertex2fv(pos, v[j]);
			}
			immEnd();

			immUniformColor4f(0.9f, 0.9f, 1.0f, 0.5f);
			GPU_line_width(1.0f);
			immBegin(GPU_PRIM_LINE_STRIP, PAINT_CURVE_NUM_SEGMENTS + 1);
			for (j = 0; j <= PAINT_CURVE_NUM_SEGMENTS; j++) {
				immVertex2fv(pos, v[j]);
			}
			immEnd();
		}

		/* draw last line segment */
		draw_bezier_handle_lines(pos, selec_col, &cp->bez);
		draw_tri_point(pos, selec_col, pivot_col, &cp->bez.vec[1][0], 10.0f, cp->bez.f2);
		draw_rect_point(pos, selec_col, handle_col, &cp->bez.vec[0][0], 8.0f, cp->bez.f1 || cp->bez.f2);
		draw_rect_point(pos, selec_col, handle_col, &cp->bez.vec[2][0], 8.0f, cp->bez.f3 || cp->bez.f2);

		GPU_blend(false);
		GPU_line_smooth(false);

		immUnbindProgram();
	}
	GPU_matrix_pop();
}

/* Special actions taken when paint cursor goes over mesh */
/* TODO: sculpt only for now */
static void paint_cursor_on_hit(
        UnifiedPaintSettings *ups, Brush *brush, ViewContext *vc,
        const float location[3])
{
	float unprojected_radius, projected_radius;

	/* update the brush's cached 3D radius */
	if (!BKE_brush_use_locked_size(vc->scene, brush)) {
		/* get 2D brush radius */
		if (ups->draw_anchored)
			projected_radius = ups->anchored_size;
		else {
			if (brush->flag & BRUSH_ANCHORED)
				projected_radius = 8;
			else
				projected_radius = BKE_brush_size_get(vc->scene, brush);
		}

		/* convert brush radius from 2D to 3D */
		unprojected_radius = paint_calc_object_space_radius(
		        vc, location, projected_radius);

		/* scale 3D brush radius by pressure */
		if (ups->stroke_active && BKE_brush_use_size_pressure(vc->scene, brush))
			unprojected_radius *= ups->size_pressure_value;

		/* set cached value in either Brush or UnifiedPaintSettings */
		BKE_brush_unprojected_radius_set(vc->scene, brush, unprojected_radius);
	}
}

static bool ommit_cursor_drawing(Paint *paint, ePaintMode mode, Brush *brush)
{
	if (paint->flags & PAINT_SHOW_BRUSH) {
		if (ELEM(mode, PAINT_MODE_TEXTURE_2D, PAINT_MODE_TEXTURE_3D) && brush->imagepaint_tool == PAINT_TOOL_FILL) {
			return true;
		}
		return false;
	}
	return true;
}

static void paint_draw_cursor(bContext *C, int x, int y, void *UNUSED(unused))
{
	Scene *scene = CTX_data_scene(C);
	ARegion *ar = CTX_wm_region(C);
	UnifiedPaintSettings *ups = &scene->toolsettings->unified_paint_settings;
	Paint *paint = BKE_paint_get_active_from_context(C);
	Brush *brush = BKE_paint_brush(paint);
	ePaintMode mode = BKE_paintmode_get_active_from_context(C);

	/* check that brush drawing is enabled */
	if (ommit_cursor_drawing(paint, mode, brush))
		return;

	/* can't use stroke vc here because this will be called during
	 * mouse over too, not just during a stroke */
	ViewContext vc;
	ED_view3d_viewcontext_init(C, &vc);

	if (vc.rv3d && (vc.rv3d->rflag & RV3D_NAVIGATING)) {
		return;
	}

	/* skip everything and draw brush here */
	if (brush->flag & BRUSH_CURVE) {
		paint_draw_curve_cursor(brush, &vc);
		return;
	}

	float zoomx, zoomy;
	get_imapaint_zoom(C, &zoomx, &zoomy);
	zoomx = max_ff(zoomx, zoomy);

	/* set various defaults */
	const float *outline_col = brush->add_col;
	const float outline_alpha = 0.5f;
	float translation[2] = { x, y };
	float final_radius = (BKE_brush_size_get(scene, brush) * zoomx);

	/* don't calculate rake angles while a stroke is active because the rake variables are global
	 * and we may get interference with the stroke itself.
	 * For line strokes, such interference is visible */
	if (!ups->stroke_active) {
		paint_calculate_rake_rotation(ups, brush, translation);
	}

	/* draw overlay */
	paint_draw_alpha_overlay(ups, brush, &vc, x, y, zoomx, mode);

	/* TODO: as sculpt and other paint modes are unified, this
	 * special mode of drawing will go away */
	if ((mode == PAINT_MODE_SCULPT) && vc.obact->sculpt) {
		float location[3];
		int pixel_radius;

		/* test if brush is over the mesh */
		bool hit = sculpt_get_brush_geometry(C, &vc, x, y, &pixel_radius, location, ups);

		if (BKE_brush_use_locked_size(scene, brush))
			BKE_brush_size_set(scene, brush, pixel_radius);

		/* check if brush is subtracting, use different color then */
		/* TODO: no way currently to know state of pen flip or
		 * invert key modifier without starting a stroke */
		if (((ups->draw_inverted == 0) ^ ((brush->flag & BRUSH_DIR_IN) == 0)) &&
		    BKE_brush_sculpt_has_secondary_color(brush))
		{
			outline_col = brush->sub_col;
		}

		/* only do if brush is over the mesh */
		if (hit)
			paint_cursor_on_hit(ups, brush, &vc, location);
	}

	if (ups->draw_anchored) {
		final_radius = ups->anchored_size;
		copy_v2_fl2(translation,
		            ups->anchored_initial_mouse[0] + ar->winrct.xmin,
		            ups->anchored_initial_mouse[1] + ar->winrct.ymin);
	}

	/* make lines pretty */
	GPU_line_width(1.0f);
	GPU_blend(true); /* TODO: also set blend mode? */
	GPU_line_smooth(true);

	uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
	immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);

	/* set brush color */
	immUniformColor3fvAlpha(outline_col, outline_alpha);

	/* draw brush outline */
	if (ups->stroke_active && BKE_brush_use_size_pressure(scene, brush)) {
		/* inner at full alpha */
		imm_draw_circle_wire_2d(pos, translation[0], translation[1], final_radius * ups->size_pressure_value, 40);
		/* outer at half alpha */
		immUniformColor3fvAlpha(outline_col, outline_alpha * 0.5f);
	}
	imm_draw_circle_wire_2d(pos, translation[0], translation[1], final_radius, 40);

	immUnbindProgram();

	/* restore GL state */
	GPU_blend(false);
	GPU_line_smooth(false);
}

/* Public API */

void paint_cursor_start(bContext *C, bool (*poll)(bContext *C))
{
	Paint *p = BKE_paint_get_active_from_context(C);

	if (p && !p->paint_cursor) {
		p->paint_cursor = WM_paint_cursor_activate(
		        CTX_wm_manager(C),
		        SPACE_TYPE_ANY, RGN_TYPE_ANY,
		        poll,
		        paint_draw_cursor,
		        NULL);
	}

	/* invalidate the paint cursors */
	BKE_paint_invalidate_overlay_all();
}

void paint_cursor_start_explicit(Paint *p, wmWindowManager *wm, bool (*poll)(bContext *C))
{
	if (p && !p->paint_cursor) {
		p->paint_cursor = WM_paint_cursor_activate(
		        wm,
		        SPACE_TYPE_ANY, RGN_TYPE_ANY,
		        poll,
		        paint_draw_cursor,
		        NULL);
	}
}