[Bf-blender-cvs] [4d45ea99e0e] greasepencil-object: Fix blur shift when add more samples

[Antonio Vazquez]

Commit: 4d45ea99e0e693ecb6918350417519fb36d5b6b5
Author: Antonio Vazquez
Date:   Fri Mar 30 16:38:50 2018 +0200
Branches: greasepencil-object
https://developer.blender.org/rB4d45ea99e0e693ecb6918350417519fb36d5b6b5

Fix blur shift when add more samples

The image was moved to top when increase the sample number. This was due the shader was bluring both axis at the same time.

===================================================================

M	source/blender/draw/engines/gpencil/gpencil_engine.c

===================================================================

diff --git a/source/blender/draw/engines/gpencil/gpencil_engine.c b/source/blender/draw/engines/gpencil/gpencil_engine.c
index 1234539f97e..c525816ef9f 100644
--- a/source/blender/draw/engines/gpencil/gpencil_engine.c
+++ b/source/blender/draw/engines/gpencil/gpencil_engine.c
@@ -644,20 +644,34 @@ static void gpencil_vfx_passes(int ob_idx, void *vedata, tGPencilObjectCache *ca
 			samples++;
 		}
 
+		/* save radius to avoid shift when apply several times the same effect */
+		float bx = stl->vfx[ob_idx].vfx_blur.radius[0];
+		float by = stl->vfx[ob_idx].vfx_blur.radius[1];
+
 		for (int b = 0; b < samples; b++) {
-			/* make a pin-pong change of framebuffer to acumulate */
+			/* make a pin-pong change of framebuffer to acumulate 
+			 * first horizontal blur and next a vertical blur.
+			 * if we try to make both at the same time, the image is shifted to top
+			 */
 			if (b % 2 == 0) {
 				GPU_framebuffer_bind(fbl->vfx_fb_b);
+				/* clean only firt time */
 				if (b == 0) {
 					GPU_framebuffer_clear_color_depth(fbl->vfx_fb_b, clearcol, 1.0f);
 				}
 				e_data.input_depth_tx = e_data.vfx_depth_tx_a;
 				e_data.input_color_tx = e_data.vfx_color_tx_a;
+				/* horizontal */
+				stl->vfx[ob_idx].vfx_blur.radius[0] = bx;
+				stl->vfx[ob_idx].vfx_blur.radius[1] = 0;
 			}
 			else {
 				e_data.input_depth_tx = e_data.vfx_depth_tx_b;
 				e_data.input_color_tx = e_data.vfx_color_tx_b;
 				GPU_framebuffer_bind(fbl->vfx_fb_a);
+				/* vertical */
+				stl->vfx[ob_idx].vfx_blur.radius[0] = 0;
+				stl->vfx[ob_idx].vfx_blur.radius[1] = by;
 			}
 			DRW_draw_pass_subset(psl->vfx_blur_pass,
 				cache->vfx_blur_sh,