More usage of GLSL for color managed image drawing

Uses GLSL for drawing image in Image Editor space.

This requires change in image_buffer_rect_update, so
original float buffer is being updated as well. This
is unlikely be something bad, but will keep an eye
on this change.

Also no byte buffer allocation happens there, this
is so because byte buffer used for display only
and in case of GLSL display such allocation and
partial update is just waste of time.

Also switched OpenGL render from using CPU color
space linearization to GLSL color space transform.
Makes OpenGL rendering pretty much faster (but
still slower than in 2.60).

internal changes:

- Added functions to setup GLSL shader for color
  space conversion in colormanagement.c. Currently
  conversion form a colorspace defined by a role to
  linear space is implemented. Easy to extend to
  other cases.

- Added helper functions to glutil.c which does
  smarter image buffer draw (calling all needed OCIO
  stuff, editors now could draw image buffer with a
  single function call -- all the checks are done in
  glutil.c).

- Also added helper function for buffer linearization
  from a given role to glutil.c. Everyone now able to
  linearize buffer with a single call.

  This function will do nothing is GLSL routines fails
  or not supported.

  And one last this: this function uses offscreen
  drawing, could potentially give issues on some
  cards, also will keep an eye on this.

7 files changed, 138 insertions, 80 deletions

diff --git a/source/blender/editors/include/BIF_glutil.h b/source/blender/editors/include/BIF_glutil.h
index 5774a057eb5..650e4527196 100644
--- a/source/blender/editors/include/BIF_glutil.h
+++ b/source/blender/editors/include/BIF_glutil.h
@@ -33,6 +33,9 @@
 struct rcti;
 struct rctf;
 
+struct ImBuf;
+struct bContext;
+
 void fdrawbezier(float vec[4][3]);
 void fdrawline(float x1, float y1, float x2, float y2);
 void fdrawbox(float x1, float y1, float x2, float y2);
@@ -223,5 +226,13 @@ typedef struct bglMats {
 } bglMats;
 void bgl_get_mats(bglMats *mats);
 
+/* **** Color management helper functions for GLSL display/transform ***** */
+
+/* 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);
+
+/* Transform buffer from role to scene linear space using GLSL OCIO conversion */
+int glaBufferTransformFromRole_glsl(float *buffer, int width, int height, int role);
+
 #endif /* __BIF_GLUTIL_H__ */
 
diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index 365ac02d15b..de8accf0180 100644
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -140,15 +140,23 @@ void image_buffer_rect_update(Scene *scene, RenderResult *rr, ImBuf *ibuf, volat
 		}
 	}
 	if (rectf == NULL) return;
-
-	if (ibuf->rect == NULL)
-		imb_addrectImBuf(ibuf);
 	
 	rectf += 4 * (rr->rectx * ymin + xmin);
 
-	IMB_partial_display_buffer_update(ibuf, rectf, NULL, rr->rectx, rxmin, rymin,
-	                                  &scene->view_settings, &scene->display_settings,
-	                                  rxmin, rymin, rxmin + xmax, rymin + ymax, TRUE);
+	if (ibuf->rect) {
+		IMB_partial_display_buffer_update(ibuf, rectf, NULL, rr->rectx, rxmin, rymin,
+		                                  &scene->view_settings, &scene->display_settings,
+		                                  rxmin, rymin, rxmin + xmax, rymin + ymax, TRUE);
+	}
+
+	/* update float buffer as well, so fast GLSL display could use it
+	 *
+	 * TODO(sergey): not actually sure it is nice thing to modify something here
+	 *               but ibuf->rect used to be modified here
+	 */
+	IMB_buffer_float_from_float(ibuf->rect_float + 4 * (ibuf->x * rymin + rxmin), rectf,
+	                            4, IB_PROFILE_LINEAR_RGB, IB_PROFILE_LINEAR_RGB, FALSE,
+	                            xmax, ymax, ibuf->x, rr->rectx);
 }
 
 /* ****************************** render invoking ***************** */
diff --git a/source/blender/editors/render/render_opengl.c b/source/blender/editors/render/render_opengl.c
index f47d737beca..9d443fab552 100644
--- a/source/blender/editors/render/render_opengl.c
+++ b/source/blender/editors/render/render_opengl.c
@@ -69,6 +69,8 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
+#include "BIF_gl.h"
+#include "BIF_glutil.h"
 
 #include "GPU_extensions.h"
 
@@ -261,11 +263,14 @@ static void screen_opengl_render_apply(OGLRender *oglrender)
 	 */
 
 	if (!oglrender->is_sequencer) {
-		/* sequencer has got tricker ocnversion happened above */
-
-		IMB_buffer_float_from_float(rr->rectf, rr->rectf,
-		                            4, IB_PROFILE_LINEAR_RGB, IB_PROFILE_SRGB, TRUE,
-		                            oglrender->sizex, oglrender->sizey, oglrender->sizex, oglrender->sizex);
+		/* sequencer has got trickier conversion happened above
+		 * also assume opengl's space matches byte buffer color space
+		 */
+		if (!glaBufferTransformFromRole_glsl(rr->rectf, oglrender->sizex, oglrender->sizey, COLOR_ROLE_DEFAULT_BYTE)) {
+			IMB_buffer_float_from_float(rr->rectf, rr->rectf,
+			                            4, IB_PROFILE_LINEAR_RGB, IB_PROFILE_SRGB, TRUE,
+			                            oglrender->sizex, oglrender->sizey, oglrender->sizex, oglrender->sizex);
+		}
 	}
 
 	/* rr->rectf is now filled with image data */
diff --git a/source/blender/editors/screen/CMakeLists.txt b/source/blender/editors/screen/CMakeLists.txt
index 33373354aa4..c9c4c253e28 100644
--- a/source/blender/editors/screen/CMakeLists.txt
+++ b/source/blender/editors/screen/CMakeLists.txt
@@ -25,6 +25,7 @@ set(INC
 	../../blenlib
 	../../blenloader
 	../../bmesh
+	../../gpu
 	../../imbuf
 	../../makesdna
 	../../makesrna
diff --git a/source/blender/editors/screen/glutil.c b/source/blender/editors/screen/glutil.c
index 89315e041de..fecb3c58a2d 100644
--- a/source/blender/editors/screen/glutil.c
+++ b/source/blender/editors/screen/glutil.c
@@ -43,10 +43,16 @@
 
 #include "BKE_blender.h"
 #include "BKE_colortools.h"
+#include "BKE_context.h"
 
 #include "BIF_gl.h"
 #include "BIF_glutil.h"
 
+#include "GPU_extensions.h"
+
+#include "IMB_colormanagement.h"
+#include "IMB_imbuf_types.h"
+
 #ifndef GL_CLAMP_TO_EDGE
 #define GL_CLAMP_TO_EDGE                        0x812F
 #endif
@@ -983,3 +989,89 @@ void bglFlush(void)
 #endif
 }
 #endif
+
+/* **** Color management helper functions for GLSL display/transform ***** */
+
+/* Draw given image buffer on a screen using GLSL for display transform */
+void glaDrawImBuf_glsl_ctx(const bContext *C, ImBuf *ibuf, float x, float y, int zoomfilter)
+{
+	bool need_fallback = true;
+
+	/* Bytes and dithering are not supported on GLSL yet */
+	if (ibuf->rect_float && ibuf->dither == 0.0f) {
+		if (IMB_colormanagement_setup_glsl_draw_from_ctx(C)) {
+			glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
+			glColor4f(1.0, 1.0, 1.0, 1.0);
+
+			glaDrawPixelsTex(x, y, ibuf->x, ibuf->y, GL_FLOAT, zoomfilter, ibuf->rect_float);
+
+			IMB_colormanagement_finish_glsl_draw();
+
+			need_fallback = false;
+		}
+	}
+
+	if (need_fallback) {
+		unsigned char *display_buffer;
+		void *cache_handle;
+
+		display_buffer = IMB_display_buffer_acquire_ctx(C, ibuf, &cache_handle);
+
+		if (display_buffer)
+			glaDrawPixelsAuto(x, y, ibuf->x, ibuf->y, GL_UNSIGNED_BYTE, zoomfilter, display_buffer);
+
+		IMB_display_buffer_release(cache_handle);
+	}
+}
+
+/* Transform buffer from role to scene linear space using GLSL OCIO conversion
+ *
+ * See IMB_colormanagement_setup_transform_from_role_glsl description for
+ * some more details
+ */
+int glaBufferTransformFromRole_glsl(float *buffer, int width, int height, int role)
+{
+	GPUOffScreen *ofs;
+	char err_out[256];
+	rcti display_rect;
+
+	ofs = GPU_offscreen_create(width, height, err_out);
+
+	if (!ofs)
+		return FALSE;
+
+	GPU_offscreen_bind(ofs);
+
+	if (!IMB_colormanagement_setup_transform_from_role_glsl(role)) {
+		GPU_offscreen_unbind(ofs);
+		GPU_offscreen_free(ofs);
+		return FALSE;
+	}
+
+	BLI_rcti_init(&display_rect, 0, width, 0, height);
+
+	glMatrixMode(GL_PROJECTION);
+	glPushMatrix();
+	glMatrixMode(GL_MODELVIEW);
+	glPushMatrix();
+
+	glaDefine2DArea(&display_rect);
+	glLoadIdentity();
+
+	glaDrawPixelsTex(0, 0, width, height, GL_FLOAT, GL_NEAREST, buffer);
+
+	glMatrixMode(GL_PROJECTION);
+	glPopMatrix();
+	glMatrixMode(GL_MODELVIEW);
+	glPopMatrix();
+
+	GPU_offscreen_read_pixels(ofs, GL_FLOAT, buffer);
+
+	IMB_colormanagement_finish_glsl_transform();
+
+	/* unbind */
+	GPU_offscreen_unbind(ofs);
+	GPU_offscreen_free(ofs);
+
+	return TRUE;
+}
diff --git a/source/blender/editors/space_clip/clip_draw.c b/source/blender/editors/space_clip/clip_draw.c
index cbca2f0c46e..774220764e7 100644
--- a/source/blender/editors/space_clip/clip_draw.c
+++ b/source/blender/editors/space_clip/clip_draw.c
@@ -248,53 +248,6 @@ static void draw_movieclip_notes(SpaceClip *sc, ARegion *ar)
 		ED_region_info_draw(ar, str, block, 0.6f);
 }
 
-static void draw_movieclip_buffer_glsl(SpaceClip *sc, ImBuf *ibuf, int x, int y,
-                                       float zoomx, float zoomy)
-{
-	MovieClip *clip = ED_space_clip_get_clip(sc);
-	int filter = GL_LINEAR;
-
-	glPushMatrix();
-	glTranslatef(x, y, 0.0f);
-	glScalef(zoomx, zoomy, 1.0f);
-
-	glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
-
-	glColor4f(1.0, 1.0, 1.0, 1.0);
-
-	/* non-scaled proxy shouldn;t use diltering */
-	if ((clip->flag & MCLIP_USE_PROXY) == 0 ||
-	    ELEM(sc->user.render_size, MCLIP_PROXY_RENDER_SIZE_FULL, MCLIP_PROXY_RENDER_SIZE_100))
-	{
-		filter = GL_NEAREST;
-	}
-
-	glaDrawPixelsTex(0, 0, ibuf->x, ibuf->y, GL_FLOAT, filter, ibuf->rect_float);
-
-	glPopMatrix();
-}
-
-static void draw_movieclip_buffer_fallback(const bContext *C, ImBuf *ibuf, int x, int y,
-                                           int width, int height, float zoomx, float zoomy)
-{
-	unsigned char *display_buffer;
-	void *cache_handle;
-
-	display_buffer = IMB_display_buffer_acquire_ctx(C, ibuf, &cache_handle);
-
-	if (display_buffer) {
-		/* set zoom */
-		glPixelZoom(zoomx * width / ibuf->x, zoomy * height / ibuf->y);
-
-		glaDrawPixelsAuto(x, y, ibuf->x, ibuf->y, GL_UNSIGNED_BYTE, GL_NEAREST, display_buffer);
-
-		/* reset zoom */
-		glPixelZoom(1.0f, 1.0f);
-	}
-
-	IMB_display_buffer_release(cache_handle);
-}
-
 static void draw_movieclip_buffer(const bContext *C, SpaceClip *sc, ARegion *ar, ImBuf *ibuf,
                                   int width, int height, float zoomx, float zoomy)
 {
@@ -308,7 +261,8 @@ static void draw_movieclip_buffer(const bContext *C, SpaceClip *sc, ARegion *ar,
 		glRectf(x, y, x + zoomx * width, y + zoomy * height);
 	}
 	else {
-		bool need_fallback = true;
+		MovieClip *clip = ED_space_clip_get_clip(sc);
+		int filter = GL_LINEAR;
 
 		/* checkerboard for case alpha */
 		if (ibuf->planes == 32) {
@@ -318,19 +272,14 @@ static void draw_movieclip_buffer(const bContext *C, SpaceClip *sc, ARegion *ar,
 			fdrawcheckerboard(x, y, x + zoomx * ibuf->x, y + zoomy * ibuf->y);
 		}
 
-		/* GLSL display transform for byte buffers is not supported yet */
-		if (ibuf->rect_float && IMB_coloemanagement_setup_glsl_draw_from_ctx(C)) {
-			draw_movieclip_buffer_glsl(sc, ibuf, x, y, zoomx, zoomy);
-
-			IMB_coloemanagement_finish_glsl_draw();
-
-			need_fallback = false;
-		}
+		/* non-scaled proxy shouldn't use filtering */
+		if ((clip->flag & MCLIP_USE_PROXY) == 0 ||
+		    ELEM(sc->user.render_size, MCLIP_PROXY_RENDER_SIZE_FULL, MCLIP_PROXY_RENDER_SIZE_100))
+			{
+				filter = GL_NEAREST;
+			}
 
-		/* if GLSL display failed, fallback to regular glaDrawPixelsAuto method */
-		if (need_fallback) {
-			draw_movieclip_buffer_fallback(C, ibuf, x, y, width, height, zoomx, zoomy);
-		}
+		glaDrawImBuf_glsl_ctx(C, ibuf, x, y, GL_NEAREST);
 
 		if (ibuf->planes == 32)
 			glDisable(GL_BLEND);
diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index f27a99ac44b..7fc83809b60 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -505,9 +505,6 @@ static void draw_image_buffer(const bContext *C, SpaceImage *sima, ARegion *ar,
 			sima_draw_zbuffloat_pixels(scene, x, y, ibuf->x, ibuf->y, ibuf->rect_float);
 	}
 	else {
-		unsigned char *display_buffer;
-		void *cache_handle;
-
 		if (sima->flag & SI_USE_ALPHA) {
 			glEnable(GL_BLEND);
 			glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
@@ -515,12 +512,7 @@ static void draw_image_buffer(const bContext *C, SpaceImage *sima, ARegion *ar,
 			fdrawcheckerboard(x, y, x + ibuf->x * zoomx, y + ibuf->y * zoomy);
 		}
 
-		display_buffer = IMB_display_buffer_acquire_ctx(C, ibuf, &cache_handle);
-
-		if (display_buffer)
-			glaDrawPixelsAuto(x, y, ibuf->x, ibuf->y, GL_UNSIGNED_BYTE, GL_NEAREST, display_buffer);
-
-		IMB_display_buffer_release(cache_handle);
+		glaDrawImBuf_glsl_ctx(C, ibuf, x, y, GL_NEAREST);
 
 		if (sima->flag & SI_USE_ALPHA)
 			glDisable(GL_BLEND);