Revert "Fix part of T41406"

This reverts commit 7c7cb01aa5641414d9f0c39ab81df0f57205f362.

The smoothing weights will cause shifting in the image if not calculated
as they were in the branch. Solution for better performance will be to force-clip
kernel to a square of size two for projective painting.

4 files changed, 17 insertions, 14 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_image.c b/source/blender/editors/sculpt_paint/paint_image.c
index 5a4fda033d8..e9e1615b27d 100644
--- a/source/blender/editors/sculpt_paint/paint_image.c
+++ b/source/blender/editors/sculpt_paint/paint_image.c
@@ -515,10 +515,10 @@ BlurKernel *paint_new_blur_kernel(Brush *br)
 {
 	int i, j;
 	BlurKernel *kernel = MEM_mallocN(sizeof(BlurKernel), "blur kernel");
-	float pixel_len = br->blur_kernel_radius / 2.0f;
+	int pixel_len = br->blur_kernel_radius;
 	BlurKernelType type = br->blur_mode;
 
-	kernel->side = br->blur_kernel_radius + 1;
+	kernel->side = pixel_len * 2 + 1;
 	kernel->side_squared = kernel->side * kernel->side;
 	kernel->wdata = MEM_mallocN(sizeof(float) * kernel->side_squared, "blur kernel data");
 	kernel->pixel_len = pixel_len;
@@ -531,19 +531,26 @@ BlurKernel *paint_new_blur_kernel(Brush *br)
 
 		case KERNEL_GAUSSIAN:
 		{
-			float standard_dev = pixel_len / 3.0f; /* at standard deviation of 3.0 kernel is at about zero */
+			float standard_dev = pixel_len / 3.0; /* at standard deviation of 3.0 kernel is at about zero */
+			int i_term = pixel_len + 1;
 
 			/* make the necessary adjustment to the value for use in the normal distribution formula */
 			standard_dev = standard_dev * standard_dev * 2;
 
-			for (i = 0; i < kernel->side; i++) {
-				for (j = 0; j < kernel->side; j++) {
+			kernel->wdata[pixel_len + pixel_len * kernel->side] = 1.0;
+			/* fill in all four quadrants at once */
+			for (i = 0; i < i_term; i++) {
+				for (j = 0; j < pixel_len; j++) {
 					float idist = pixel_len - i;
 					float jdist = pixel_len - j;
 
 					float value = exp((idist * idist + jdist * jdist) / standard_dev);
 
-					kernel->wdata[i + j * kernel->side] = value;
+					kernel->wdata[i + j * kernel->side] =
+					kernel->wdata[(kernel->side - j - 1) + i * kernel->side] =
+					kernel->wdata[(kernel->side - i - 1) + (kernel->side - j - 1) * kernel->side] =
+					kernel->wdata[j + (kernel->side - i - 1) * kernel->side] =
+						value;
 				}
 			}
 
diff --git a/source/blender/editors/sculpt_paint/paint_image_2d.c b/source/blender/editors/sculpt_paint/paint_image_2d.c
index 14429eb8aca..1cba8a2cf23 100644
--- a/source/blender/editors/sculpt_paint/paint_image_2d.c
+++ b/source/blender/editors/sculpt_paint/paint_image_2d.c
@@ -877,10 +877,8 @@ static void paint_2d_lift_soften(ImagePaintState *s, ImBuf *ibuf, ImBuf *ibufb,
 
 			for (yk = 0; yk < kernel->side; yk++) {
 				for (xk = 0; xk < kernel->side; xk++) {
-					float x_offs = xk - kernel->pixel_len;
-					float y_offs = yk - kernel->pixel_len;
-					count += paint_2d_ibuf_add_if(ibuf, xi + signf(x_offs) * fabs(x_offs + 0.51f),
-					                               yi + signf(y_offs) * fabs(y_offs + 0.51f), outrgb, is_torus,
+					count += paint_2d_ibuf_add_if(ibuf, xi + xk - kernel->pixel_len,
+					                               yi + yk - kernel->pixel_len, outrgb, is_torus,
 					                               kernel->wdata[xk + yk * kernel->side]);
 				}
 			}
diff --git a/source/blender/editors/sculpt_paint/paint_image_proj.c b/source/blender/editors/sculpt_paint/paint_image_proj.c
index 72c226f825b..4b381c90119 100644
--- a/source/blender/editors/sculpt_paint/paint_image_proj.c
+++ b/source/blender/editors/sculpt_paint/paint_image_proj.c
@@ -3763,9 +3763,7 @@ static void do_projectpaint_soften_f(ProjPaintState *ps, ProjPixel *projPixel, f
 	for (yk = 0; yk < kernel->side; yk++) {
 		for (xk = 0; xk < kernel->side; xk++) {
 			float rgba_tmp[4];
-			float x_offs = xk - kernel->pixel_len;
-			float y_offs = yk - kernel->pixel_len;
-			float co_ofs[2] = {x_offs, y_offs};
+			float co_ofs[2] = {xk - kernel->pixel_len, yk - kernel->pixel_len};
 
 			add_v2_v2(co_ofs, projPixel->projCoSS);
 
diff --git a/source/blender/editors/sculpt_paint/paint_intern.h b/source/blender/editors/sculpt_paint/paint_intern.h
index 8d42bbb7800..d0cd59d7be6 100644
--- a/source/blender/editors/sculpt_paint/paint_intern.h
+++ b/source/blender/editors/sculpt_paint/paint_intern.h
@@ -288,7 +288,7 @@ typedef struct {
 	float *wdata; /* actual kernel */
 	int side; /* kernel side */
 	int side_squared; /* data side */
-	float pixel_len; /* pixels around center that kernel is wide */
+	int pixel_len; /* pixels around center that kernel is wide */
 } BlurKernel;
 
 enum BlurKernelType;