3D mapping for projective texture painting (only for draw brush). Useful

to draw with procedural textures on surface of object. 2D painting will
still paint as if tiled.

When we unify the paint systems, the texture sampling functions will
need to be changed. Sculpt uses a slightly different system that passes
both screen and 3d coordinates to the sampling function. This commit
however is not too disrupting for that however so it can go in now.

2 files changed, 49 insertions, 9 deletions

diff --git a/source/blender/blenkernel/BKE_brush.h b/source/blender/blenkernel/BKE_brush.h
index 248fe9c8968..b19a9c4d4eb 100644
--- a/source/blender/blenkernel/BKE_brush.h
+++ b/source/blender/blenkernel/BKE_brush.h
@@ -67,7 +67,8 @@ float BKE_brush_curve_strength_clamp(struct Brush *br, float p, const float len)
 float BKE_brush_curve_strength(struct Brush *br, float p, const float len); /* used for sculpt */
 
 /* sampling */
-void BKE_brush_sample_tex(const struct Scene *scene, struct Brush *brush, const float xy[2], float rgba[4], const int thread);
+void BKE_brush_sample_tex(const struct Scene *scene, struct Brush *brush, const float sampleco[3], float rgba[4], const int thread);
+void BKE_brush_sample_tex_2D(const struct Scene *scene, struct Brush *brush, const float xy[2], float rgba[4], const int thread);
 void BKE_brush_imbuf_new(const struct Scene *scene, struct Brush *brush, short flt, short texfalloff, int size,
                          struct ImBuf **imbuf, int use_color_correction);
 
diff --git a/source/blender/blenkernel/intern/brush.c b/source/blender/blenkernel/intern/brush.c
index e8275471b09..bb4f073a3d7 100644
--- a/source/blender/blenkernel/intern/brush.c
+++ b/source/blender/blenkernel/intern/brush.c
@@ -471,8 +471,46 @@ int BKE_brush_clone_image_delete(Brush *brush)
 	return 0;
 }
 
-/* Brush Sampling */
-void BKE_brush_sample_tex(const Scene *scene, Brush *brush, const float xy[2], float rgba[4], const int thread)
+/* Brush Sampling for 3d brushes. Currently used for texture painting only, but should be generalized */
+void BKE_brush_sample_tex(const Scene *scene, Brush *brush, const float sampleco[3], float rgba[4], const int thread)
+{
+	MTex *mtex = &brush->mtex;
+
+	if (mtex && mtex->tex) {
+		float co[3], tin, tr, tg, tb, ta;
+		int hasrgb;
+		const int radius = BKE_brush_size_get(scene, brush);
+
+		if (brush->mtex.brush_map_mode == MTEX_MAP_MODE_3D) {
+			copy_v3_v3(co, sampleco);
+		} else {
+			co[0] = sampleco[0] / radius;
+			co[1] = sampleco[1] / radius;
+			co[2] = 0.0f;
+		}
+
+		hasrgb = externtex(mtex, co, &tin, &tr, &tg, &tb, &ta, thread);
+
+		if (hasrgb) {
+			rgba[0] = tr;
+			rgba[1] = tg;
+			rgba[2] = tb;
+			rgba[3] = ta;
+		}
+		else {
+			rgba[0] = tin;
+			rgba[1] = tin;
+			rgba[2] = tin;
+			rgba[3] = 1.0f;
+		}
+	}
+	else {
+		rgba[0] = rgba[1] = rgba[2] = rgba[3] = 1.0f;
+	}
+}
+
+/* Brush Sampling for 2D brushes. when we unify the brush systems this will be necessarily a separate function */
+void BKE_brush_sample_tex_2D(const Scene *scene, Brush *brush, const float xy[2], float rgba[4], const int thread)
 {
 	MTex *mtex = &brush->mtex;
 
@@ -505,7 +543,8 @@ void BKE_brush_sample_tex(const Scene *scene, Brush *brush, const float xy[2], f
 	}
 }
 
-/* TODO, use define for 'texfall' arg */
+/* TODO, use define for 'texfall' arg
+ * NOTE: only used for 2d brushes currently! */
 void BKE_brush_imbuf_new(const Scene *scene, Brush *brush, short flt, short texfall, int bufsize, ImBuf **outbuf, int use_color_correction)
 {
 	ImBuf *ibuf;
@@ -544,10 +583,10 @@ void BKE_brush_imbuf_new(const Scene *scene, Brush *brush, short flt, short texf
 					dstf[3] = alpha * BKE_brush_curve_strength_clamp(brush, len_v2(xy), radius);
 				}
 				else if (texfall == 1) {
-					BKE_brush_sample_tex(scene, brush, xy, dstf, 0);
+					BKE_brush_sample_tex_2D(scene, brush, xy, dstf, 0);
 				}
 				else {
-					BKE_brush_sample_tex(scene, brush, xy, rgba, 0);
+					BKE_brush_sample_tex_2D(scene, brush, xy, rgba, 0);
 					mul_v3_v3v3(dstf, rgba, brush_rgb);
 					dstf[3] = rgba[3] * alpha * BKE_brush_curve_strength_clamp(brush, len_v2(xy), radius);
 				}
@@ -574,11 +613,11 @@ void BKE_brush_imbuf_new(const Scene *scene, Brush *brush, short flt, short texf
 					dst[3] = FTOCHAR(alpha_f);
 				}
 				else if (texfall == 1) {
-					BKE_brush_sample_tex(scene, brush, xy, rgba, 0);
+					BKE_brush_sample_tex_2D(scene, brush, xy, rgba, 0);
 					rgba_float_to_uchar(dst, rgba);
 				}
 				else if (texfall == 2) {
-					BKE_brush_sample_tex(scene, brush, xy, rgba, 0);
+					BKE_brush_sample_tex_2D(scene, brush, xy, rgba, 0);
 					mul_v3_v3(rgba, brush->rgb);
 					alpha_f = rgba[3] * alpha * BKE_brush_curve_strength_clamp(brush, len_v2(xy), radius);
 
@@ -587,7 +626,7 @@ void BKE_brush_imbuf_new(const Scene *scene, Brush *brush, short flt, short texf
 					dst[3] = FTOCHAR(alpha_f);
 				}
 				else {
-					BKE_brush_sample_tex(scene, brush, xy, rgba, 0);
+					BKE_brush_sample_tex_2D(scene, brush, xy, rgba, 0);
 					alpha_f = rgba[3] * alpha * BKE_brush_curve_strength_clamp(brush, len_v2(xy), radius);
 
 					dst[0] = crgb[0];