Clip invisible parts of image when drawing in 2D textures and GLSL Modes

This commit avoids draw of invisible parts of image in image editor,
making it faster to re-draw the image.

Especially handy when painting on a high-res image when zoomed-in.

3 files changed, 111 insertions, 18 deletions

diff --git a/source/blender/editors/include/BIF_glutil.h b/source/blender/editors/include/BIF_glutil.h
index e45e5f5e7ab..0ac5c17a552 100644
--- a/source/blender/editors/include/BIF_glutil.h
+++ b/source/blender/editors/include/BIF_glutil.h
@@ -143,6 +143,8 @@ void glaDrawPixelsSafe(float x, float y, int img_w, int img_h, int row_w, int fo
  */
 
 void glaDrawPixelsTex(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect);
+void glaDrawPixelsTex_clipping(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect,
+                               float clip_min_x, float clip_min_y, float clip_max_x, float clip_max_y);
 
 /**
  * glaDrawPixelsAuto - Switches between texture or pixel drawing using UserDef.
@@ -150,9 +152,13 @@ void glaDrawPixelsTex(float x, float y, int img_w, int img_h, int format, int ty
  * needs glaDefine2DArea to be set.
  */
 void glaDrawPixelsAuto(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect);
+void glaDrawPixelsAuto_clipping(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect,
+                                float clip_min_x, float clip_min_y, float clip_max_x, float clip_max_y);
 
 
 void glaDrawPixelsTexScaled(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect, float scaleX, float scaleY);
+void glaDrawPixelsTexScaled_clipping(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect, float scaleX, float scaleY,
+                                     float clip_min_x, float clip_min_y, float clip_max_x, float clip_max_y);
 
 /* 2D Drawing Assistance */
 
@@ -205,9 +211,21 @@ void bgl_get_mats(bglMats *mats);
 void glaDrawImBuf_glsl(struct ImBuf *ibuf, float x, float y, int zoomfilter,
                        struct ColorManagedViewSettings *view_settings,
                        struct ColorManagedDisplaySettings *display_settings);
+void glaDrawImBuf_glsl_clipping(struct ImBuf *ibuf, float x, float y, int zoomfilter,
+                                struct ColorManagedViewSettings *view_settings,
+                                struct ColorManagedDisplaySettings *display_settings,
+                                float clip_min_x, float clip_min_y,
+                                float clip_max_x, float clip_max_y);
+
 
 /* Draw imbuf on a screen, preferably using GLSL display transform */
 void glaDrawImBuf_glsl_ctx(const struct bContext *C, struct ImBuf *ibuf, float x, float y, int zoomfilter);
+void glaDrawImBuf_glsl_ctx_clipping(const struct bContext *C,
+                                    struct ImBuf *ibuf,
+                                    float x, float y,
+                                    int zoomfilter,
+                                    float clip_min_x, float clip_min_y,
+                                    float clip_max_x, float clip_max_y);
 
 void glaDrawBorderCorners(const struct rcti *border, float zoomx, float zoomy);
 
diff --git a/source/blender/editors/screen/glutil.c b/source/blender/editors/screen/glutil.c
index a1c330d9dff..cbf87062955 100644
--- a/source/blender/editors/screen/glutil.c
+++ b/source/blender/editors/screen/glutil.c
@@ -368,7 +368,11 @@ static int get_cached_work_texture(int *r_w, int *r_h)
 	return texid;
 }
 
-void glaDrawPixelsTexScaled(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect, float scaleX, float scaleY)
+void glaDrawPixelsTexScaled_clipping(float x, float y, int img_w, int img_h,
+                                     int format, int type, int zoomfilter, void *rect,
+                                     float scaleX, float scaleY,
+                                     float clip_min_x, float clip_min_y,
+                                     float clip_max_x, float clip_max_y)
 {
 	unsigned char *uc_rect = (unsigned char *) rect;
 	const float *f_rect = (float *)rect;
@@ -377,6 +381,7 @@ void glaDrawPixelsTexScaled(float x, float y, int img_w, int img_h, int format,
 	int seamless, offset_x, offset_y, nsubparts_x, nsubparts_y;
 	int texid = get_cached_work_texture(&tex_w, &tex_h);
 	int components;
+	const bool use_clipping = ((clip_min_x < clip_max_x) && (clip_min_y < clip_max_y));
 
 	/* Specify the color outside this function, and tex will modulate it.
 	 * This is useful for changing alpha without using glPixelTransferf()
@@ -443,11 +448,23 @@ void glaDrawPixelsTexScaled(float x, float y, int img_w, int img_h, int format,
 			int offset_top = (seamless && remainder_y > tex_h) ? 1 : 0;
 			float rast_x = x + subpart_x * offset_x * xzoom;
 			float rast_y = y + subpart_y * offset_y * yzoom;
-			
 			/* check if we already got these because we always get 2 more when doing seamless */
 			if (subpart_w <= seamless || subpart_h <= seamless)
 				continue;
-			
+
+			if (use_clipping) {
+				if (rast_x + (float)(subpart_w - offset_right) * xzoom * scaleX < clip_min_x ||
+				    rast_y + (float)(subpart_h - offset_top) * yzoom * scaleY < clip_min_y)
+				{
+					continue;
+				}
+				if (rast_x + (float)offset_left * xzoom > clip_max_x ||
+				    rast_y + (float)offset_bot * yzoom > clip_max_y)
+				{
+					continue;
+				}
+			}
+
 			if (type == GL_FLOAT) {
 				glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, subpart_w, subpart_h, format, GL_FLOAT, &f_rect[((size_t)subpart_y) * offset_y * img_w * components + subpart_x * offset_x * components]);
 				
@@ -497,9 +514,26 @@ void glaDrawPixelsTexScaled(float x, float y, int img_w, int img_h, int format,
 #endif
 }
 
+void glaDrawPixelsTexScaled(float x, float y, int img_w, int img_h,
+                            int format, int type, int zoomfilter, void *rect,
+                            float scaleX, float scaleY)
+{
+	glaDrawPixelsTexScaled_clipping(x, y, img_w, img_h, format, type, zoomfilter, rect,
+	                                scaleX, scaleY, 0.0f, 0.0f, 0.0f, 0.0f);
+}
+
 void glaDrawPixelsTex(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect)
 {
-	glaDrawPixelsTexScaled(x, y, img_w, img_h, format, type, zoomfilter, rect, 1.0f, 1.0f);
+	glaDrawPixelsTexScaled_clipping(x, y, img_w, img_h, format, type, zoomfilter, rect, 1.0f, 1.0f,
+	                                0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void glaDrawPixelsTex_clipping(float x, float y, int img_w, int img_h,
+                               int format, int type, int zoomfilter, void *rect,
+                               float clip_min_x, float clip_min_y, float clip_max_x, float clip_max_y)
+{
+	glaDrawPixelsTexScaled_clipping(x, y, img_w, img_h, format, type, zoomfilter, rect, 1.0f, 1.0f,
+	                                clip_min_x, clip_min_y, clip_max_x, clip_max_y);
 }
 
 void glaDrawPixelsSafe(float x, float y, int img_w, int img_h, int row_w, int format, int type, void *rect)
@@ -580,17 +614,27 @@ void glaDrawPixelsSafe(float x, float y, int img_w, int img_h, int row_w, int fo
 }
 
 /* uses either DrawPixelsSafe or DrawPixelsTex, based on user defined maximum */
-void glaDrawPixelsAuto(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect)
+void glaDrawPixelsAuto_clipping(float x, float y, int img_w, int img_h,
+                                int format, int type, int zoomfilter, void *rect,
+                                float clip_min_x, float clip_min_y,
+                                float clip_max_x, float clip_max_y)
 {
 	if (U.image_draw_method != IMAGE_DRAW_METHOD_DRAWPIXELS) {
 		glColor4f(1.0, 1.0, 1.0, 1.0);
-		glaDrawPixelsTex(x, y, img_w, img_h, format, type, zoomfilter, rect);
+		glaDrawPixelsTex_clipping(x, y, img_w, img_h, format, type, zoomfilter, rect,
+		                          clip_min_x, clip_min_y, clip_max_x, clip_max_y);
 	}
 	else {
 		glaDrawPixelsSafe(x, y, img_w, img_h, img_w, format, type, rect);
 	}
 }
 
+void glaDrawPixelsAuto(float x, float y, int img_w, int img_h, int format, int type, int zoomfilter, void *rect)
+{
+	glaDrawPixelsAuto_clipping(x, y, img_w, img_h, format, type, zoomfilter, rect,
+	                           0.0f, 0.0f, 0.0f, 0.0f);
+}
+
 /* 2D Drawing Assistance */
 
 void glaDefine2DArea(rcti *screen_rect)
@@ -822,9 +866,11 @@ void bglPolygonOffset(float viewdist, float dist)
 /* **** Color management helper functions for GLSL display/transform ***** */
 
 /* Draw given image buffer on a screen using GLSL for display transform */
-void glaDrawImBuf_glsl(ImBuf *ibuf, float x, float y, int zoomfilter,
-                       ColorManagedViewSettings *view_settings,
-                       ColorManagedDisplaySettings *display_settings)
+void glaDrawImBuf_glsl_clipping(ImBuf *ibuf, float x, float y, int zoomfilter,
+                                ColorManagedViewSettings *view_settings,
+                                ColorManagedDisplaySettings *display_settings,
+                                float clip_min_x, float clip_min_y,
+                                float clip_max_x, float clip_max_y)
 {
 	bool force_fallback = false;
 	bool need_fallback = true;
@@ -874,14 +920,16 @@ void glaDrawImBuf_glsl(ImBuf *ibuf, float x, float y, int zoomfilter,
 					BLI_assert(!"Incompatible number of channels for GLSL display");
 
 				if (format != 0) {
-					glaDrawPixelsTex(x, y, ibuf->x, ibuf->y, format, GL_FLOAT,
-					                 zoomfilter, ibuf->rect_float);
+					glaDrawPixelsTex_clipping(x, y, ibuf->x, ibuf->y, format, GL_FLOAT,
+					                          zoomfilter, ibuf->rect_float,
+					                          clip_min_x, clip_min_y, clip_max_x, clip_max_y);
 				}
 			}
 			else if (ibuf->rect) {
 				/* ibuf->rect is always RGBA */
-				glaDrawPixelsTex(x, y, ibuf->x, ibuf->y, GL_RGBA, GL_UNSIGNED_BYTE,
-				                 zoomfilter, ibuf->rect);
+				glaDrawPixelsTex_clipping(x, y, ibuf->x, ibuf->y, GL_RGBA, GL_UNSIGNED_BYTE,
+				                          zoomfilter, ibuf->rect,
+				                          clip_min_x, clip_min_y, clip_max_x, clip_max_y);
 			}
 
 			IMB_colormanagement_finish_glsl_draw();
@@ -897,21 +945,43 @@ void glaDrawImBuf_glsl(ImBuf *ibuf, float x, float y, int zoomfilter,
 
 		display_buffer = IMB_display_buffer_acquire(ibuf, view_settings, display_settings, &cache_handle);
 
-		if (display_buffer)
-			glaDrawPixelsAuto(x, y, ibuf->x, ibuf->y, GL_RGBA, GL_UNSIGNED_BYTE, zoomfilter, display_buffer);
+		if (display_buffer) {
+			glaDrawPixelsAuto_clipping(x, y, ibuf->x, ibuf->y, GL_RGBA, GL_UNSIGNED_BYTE,
+			                           zoomfilter, display_buffer,
+			                           clip_min_x, clip_min_y, clip_max_x, clip_max_y);
+		}
 
 		IMB_display_buffer_release(cache_handle);
 	}
 }
 
-void glaDrawImBuf_glsl_ctx(const bContext *C, ImBuf *ibuf, float x, float y, int zoomfilter)
+void glaDrawImBuf_glsl(ImBuf *ibuf, float x, float y, int zoomfilter,
+                       ColorManagedViewSettings *view_settings,
+                       ColorManagedDisplaySettings *display_settings)
+{
+	glaDrawImBuf_glsl_clipping(ibuf, x, y, zoomfilter, view_settings, display_settings,
+	                           0.0f, 0.0f, 0.0f, 0.0f);
+}
+
+void glaDrawImBuf_glsl_ctx_clipping(const bContext *C,
+                                    ImBuf *ibuf,
+                                    float x, float y,
+                                    int zoomfilter,
+                                    float clip_min_x, float clip_min_y,
+                                    float clip_max_x, float clip_max_y)
 {
 	ColorManagedViewSettings *view_settings;
 	ColorManagedDisplaySettings *display_settings;
 
 	IMB_colormanagement_display_settings_from_ctx(C, &view_settings, &display_settings);
 
-	glaDrawImBuf_glsl(ibuf, x, y, zoomfilter, view_settings, display_settings);
+	glaDrawImBuf_glsl_clipping(ibuf, x, y, zoomfilter, view_settings, display_settings,
+	                           clip_min_x, clip_min_y, clip_max_x, clip_max_y);
+}
+
+void glaDrawImBuf_glsl_ctx(const bContext *C, ImBuf *ibuf, float x, float y, int zoomfilter)
+{
+	glaDrawImBuf_glsl_ctx_clipping(C, ibuf, x, y, zoomfilter, 0.0f, 0.0f, 0.0f, 0.0f);
 }
 
 void cpack(unsigned int x)
diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index 0ddbb1153c0..aff0a4c3d44 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -526,7 +526,12 @@ static void draw_image_buffer(const bContext *C, SpaceImage *sima, ARegion *ar,
 		}
 
 		if ((sima->flag & (SI_SHOW_R | SI_SHOW_G | SI_SHOW_B)) == 0) {
-			glaDrawImBuf_glsl_ctx(C, ibuf, x, y, GL_NEAREST);
+			int clip_max_x, clip_max_y;
+			UI_view2d_view_to_region(&ar->v2d,
+			                         ar->v2d.cur.xmax, ar->v2d.cur.ymax,
+			                         &clip_max_x, &clip_max_y);
+			glaDrawImBuf_glsl_ctx_clipping(C, ibuf, x, y, GL_NEAREST,
+			                               0, 0, clip_max_x, clip_max_y);
 		}
 		else {
 			unsigned char *display_buffer;