More painting fixes:

* 2D image painting with textures that contained alpha did not work correctly,
  had been broken for a while.

* 2D image panels texture (mask) panels showed wrong buttons for texture overlay.

* Texture map mode 3D now also uses masking, like Tiled and Stencil the texture
  does not move along with the brush so it works fine.

* 2D image paint View mapping did not work correct, especially noticeable with
  Rake rotation.

* Masking is now disabled for the smear tool, this can't really work because
  the original image is constantly changing and gave artifacts.

1 files changed, 33 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/math_color_blend_inline.c b/source/blender/blenlib/intern/math_color_blend_inline.c
index 121750fe919..52947fcee08 100644
--- a/source/blender/blenlib/intern/math_color_blend_inline.c
+++ b/source/blender/blenlib/intern/math_color_blend_inline.c
@@ -242,6 +242,28 @@ MINLINE void blend_color_add_alpha_byte(unsigned char dst[4], const unsigned cha
 	}
 }
 
+MINLINE void blend_color_interpolate_byte(unsigned char dst[4], const unsigned char src1[4], const unsigned char src2[4], float ft)
+{
+	/* do color interpolation, but in premultiplied space so that RGB colors
+	 * from zero alpha regions have no influence */
+	const int t = (int)(255 * ft);
+	const int mt = 255 - t;
+	int tmp = (mt * src1[3] + t * src2[3]);
+
+	if (tmp > 0) {
+		dst[0] = divide_round_i(mt * src1[0] * src1[3] + t * src2[0] * src2[3], tmp);
+		dst[1] = divide_round_i(mt * src1[1] * src1[3] + t * src2[1] * src2[3], tmp);
+		dst[2] = divide_round_i(mt * src1[2] * src1[3] + t * src2[2] * src2[3], tmp);
+		dst[3] = divide_round_i(tmp, 255);
+	}
+	else {
+		dst[0] = src1[0];
+		dst[1] = src1[1];
+		dst[2] = src1[2];
+		dst[3] = src1[3];
+	}
+}
+
 /* premultiplied alpha float blending modes */
 
 MINLINE void blend_color_mix_float(float dst[4], const float src1[4], const float src2[4])
@@ -420,4 +442,15 @@ MINLINE void blend_color_add_alpha_float(float dst[4], const float src1[4], cons
 	}
 }
 
+MINLINE void blend_color_interpolate_float(float dst[4], const float src1[4], const float src2[4], float t)
+{
+	/* interpolation, colors are premultiplied so it goes fine */
+	float mt = 1.0f - t;
+
+	dst[0] = mt * src1[0] + t * src2[0];
+	dst[1] = mt * src1[1] + t * src2[1];
+	dst[2] = mt * src1[2] + t * src2[2];
+	dst[3] = mt * src1[3] + t * src2[3];
+}
+
 #endif /* __MATH_COLOR_BLEND_INLINE_C__ */