UVEdit: Add back uv angle stretch aspect correction

This is now done in shader so that the batches are shared across ImageUV
areas.

5 files changed, 62 insertions, 13 deletions

diff --git a/source/blender/draw/intern/draw_cache_impl_mesh.c b/source/blender/draw/intern/draw_cache_impl_mesh.c
index 524e802e80d..0bac64df567 100644
--- a/source/blender/draw/intern/draw_cache_impl_mesh.c
+++ b/source/blender/draw/intern/draw_cache_impl_mesh.c
@@ -4771,7 +4771,7 @@ BLI_INLINE float edit_uv_get_stretch_area(float area, float uvarea)
 
 /* Compute face's normalized contour vectors. */
 BLI_INLINE void edit_uv_preprocess_stretch_angle(
-        float (*auv)[2], float (*av)[3], const int cd_loop_uv_offset, BMFace *efa, float asp[2])
+        float (*auv)[2], float (*av)[3], const int cd_loop_uv_offset, BMFace *efa)
 {
 	BMLoop *l;
 	BMIter liter;
@@ -4781,7 +4781,6 @@ BLI_INLINE void edit_uv_preprocess_stretch_angle(
 		MLoopUV *luv_prev = BM_ELEM_CD_GET_VOID_P(l->prev, cd_loop_uv_offset);
 
 		sub_v2_v2v2(auv[i], luv_prev->uv, luv->uv);
-		mul_v2_v2(auv[i], asp);
 		normalize_v2(auv[i]);
 
 		sub_v3_v3v3(av[i], l->prev->v->co, l->v->co);
@@ -4789,6 +4788,7 @@ BLI_INLINE void edit_uv_preprocess_stretch_angle(
 	}
 }
 
+#if 0 /* here for reference, this is done in shader now. */
 BLI_INLINE float edit_uv_get_loop_stretch_angle(
         const float auv0[2], const float auv1[2], const float av0[3], const float av1[3])
 {
@@ -4797,6 +4797,7 @@ BLI_INLINE float edit_uv_get_loop_stretch_angle(
 	float stretch = fabsf(uvang - ang) / (float)M_PI;
 	return 1.0f - pow2f(1.0f - stretch);
 }
+#endif
 
 #define VERTEX_SELECT (1 << 0)
 #define VERTEX_PINNED (1 << 1)
@@ -4823,7 +4824,7 @@ BLI_INLINE uchar edit_uv_get_loop_flag(BMLoop *l, const int cd_loop_uv_offset, S
 }
 
 static struct EditUVFormatIndex {
-	uint uvs, area, angle, flag, fdots_uvs, fdots_flag;
+	uint uvs, area, angle, uv_adj, flag, fdots_uvs, fdots_flag;
 } uv_attr_id = {0};
 
 static void uvedit_fill_buffer_data(
@@ -4885,10 +4886,7 @@ static void uvedit_fill_buffer_data(
 		if (vbo_angle) {
 			av  = (float (*)[3])BLI_buffer_reinit_data(&vec3_buf, vec3f, efa_len);
 			auv = (float (*)[2])BLI_buffer_reinit_data(&vec2_buf, vec2f, efa_len);
-			/* TODO modify shader to apply the correct aspect on the fly, or get the correct aspect.
-			 * But later solution would make it correct only in one editor at a time. */
-			float asp[2] = {1.0f, 1.0f};
-			edit_uv_preprocess_stretch_angle(auv, av, cd_loop_uv_offset, efa, asp);
+			edit_uv_preprocess_stretch_angle(auv, av, cd_loop_uv_offset, efa);
 		}
 
 		BM_ITER_ELEM_INDEX(l, &liter, efa, BM_LOOPS_OF_FACE, i) {
@@ -4897,8 +4895,14 @@ static void uvedit_fill_buffer_data(
 				GPU_vertbuf_attr_set(vbo_area, uv_attr_id.area, vidx, &area_stretch);
 			}
 			if (vbo_angle) {
-				ushort angle = 65534.0f * edit_uv_get_loop_stretch_angle(auv[i], auv[(i + 1) % efa_len],
-				                                                         av[i],  av[(i + 1) % efa_len]);
+				int i_next = (i + 1) % efa_len;
+				short suv[4];
+				/* Send uvs to the shader and let it compute the aspect corrected angle. */
+				normal_float_to_short_v2(&suv[0], auv[i]);
+				normal_float_to_short_v2(&suv[2], auv[i_next]);
+				GPU_vertbuf_attr_set(vbo_angle, uv_attr_id.uv_adj, vidx, suv);
+				/* Compute 3D angle here */
+				short angle = 32767.0f * angle_normalized_v3v3(av[i], av[i_next]) / (float)M_PI;
 				GPU_vertbuf_attr_set(vbo_angle, uv_attr_id.angle, vidx, &angle);
 			}
 			if (vbo_pos) {
@@ -4978,7 +4982,8 @@ static void mesh_create_uvedit_buffers(
 
 	if (format_pos.attr_len == 0) {
 		uv_attr_id.area  = GPU_vertformat_attr_add(&format_area,  "stretch", GPU_COMP_U16, 1, GPU_FETCH_INT_TO_FLOAT_UNIT);
-		uv_attr_id.angle = GPU_vertformat_attr_add(&format_angle, "stretch", GPU_COMP_U16, 1, GPU_FETCH_INT_TO_FLOAT_UNIT);
+		uv_attr_id.angle = GPU_vertformat_attr_add(&format_angle, "angle",   GPU_COMP_I16, 1, GPU_FETCH_INT_TO_FLOAT_UNIT);
+		uv_attr_id.uv_adj = GPU_vertformat_attr_add(&format_angle, "uv_adj", GPU_COMP_I16, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
 		uv_attr_id.flag  = GPU_vertformat_attr_add(&format_flag,  "flag",    GPU_COMP_U8,  1, GPU_FETCH_INT);
 		uv_attr_id.uvs   = GPU_vertformat_attr_add(&format_pos,   "u",     GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 		GPU_vertformat_alias_add(&format_pos, "pos");
diff --git a/source/blender/editors/uvedit/uvedit_draw.c b/source/blender/editors/uvedit/uvedit_draw.c
index 30bc6301487..46c62c4a086 100644
--- a/source/blender/editors/uvedit/uvedit_draw.c
+++ b/source/blender/editors/uvedit/uvedit_draw.c
@@ -305,7 +305,9 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, Object *obedit, Depsgraph *
 
 	if (faces) {
 		GPU_batch_program_set_builtin(faces, (draw_stretch)
-		                                     ? GPU_SHADER_2D_UV_FACES_STRETCH
+		                                     ? (sima->dt_uvstretch == SI_UVDT_STRETCH_AREA)
+		                                       ? GPU_SHADER_2D_UV_FACES_STRETCH_AREA
+		                                       : GPU_SHADER_2D_UV_FACES_STRETCH_ANGLE
 		                                     : GPU_SHADER_2D_UV_FACES);
 
 		if (!draw_stretch) {
@@ -319,6 +321,11 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, Object *obedit, Depsgraph *
 			GPU_batch_uniform_4fv(faces, "selectColor", col2);
 			GPU_batch_uniform_4fv(faces, "activeColor", col3);
 		}
+		else if (sima->dt_uvstretch == SI_UVDT_STRETCH_ANGLE) {
+			float asp[2];
+			ED_space_image_get_uv_aspect(sima, &asp[0], &asp[1]);
+			GPU_batch_uniform_2fv(faces, "aspect", asp);
+		}
 
 		GPU_batch_draw(faces);
 
diff --git a/source/blender/gpu/GPU_shader.h b/source/blender/gpu/GPU_shader.h
index ea7983f8a2e..71536523caf 100644
--- a/source/blender/gpu/GPU_shader.h
+++ b/source/blender/gpu/GPU_shader.h
@@ -349,7 +349,8 @@ typedef enum GPUBuiltinShader {
 	GPU_SHADER_2D_UV_EDGES,
 	GPU_SHADER_2D_UV_EDGES_SMOOTH,
 	GPU_SHADER_2D_UV_FACES,
-	GPU_SHADER_2D_UV_FACES_STRETCH,
+	GPU_SHADER_2D_UV_FACES_STRETCH_AREA,
+	GPU_SHADER_2D_UV_FACES_STRETCH_ANGLE,
 	/* Selection */
 	GPU_SHADER_3D_FLAT_SELECT_ID,
 	GPU_SHADER_3D_UNIFORM_SELECT_ID,
diff --git a/source/blender/gpu/intern/gpu_shader.c b/source/blender/gpu/intern/gpu_shader.c
index 88d4f1e5c52..8a3581c54df 100644
--- a/source/blender/gpu/intern/gpu_shader.c
+++ b/source/blender/gpu/intern/gpu_shader.c
@@ -933,7 +933,10 @@ static const GPUShaderStages builtin_shader_stages[GPU_NUM_BUILTIN_SHADERS] = {
 	[GPU_SHADER_2D_UV_FACES] =
 		{ datatoc_gpu_shader_2D_edituvs_faces_vert_glsl,
 		  datatoc_gpu_shader_flat_color_frag_glsl },
-	[GPU_SHADER_2D_UV_FACES_STRETCH] =
+	[GPU_SHADER_2D_UV_FACES_STRETCH_AREA] =
+		{ datatoc_gpu_shader_2D_edituvs_stretch_vert_glsl,
+		  datatoc_gpu_shader_2D_smooth_color_frag_glsl },
+	[GPU_SHADER_2D_UV_FACES_STRETCH_ANGLE] =
 		{ datatoc_gpu_shader_2D_edituvs_stretch_vert_glsl,
 		  datatoc_gpu_shader_2D_smooth_color_frag_glsl },
 
@@ -1010,6 +1013,9 @@ static const char *gpu_shader_get_builtin_shader_defines(
 		case GPU_SHADER_3D_UNIFORM_SELECT_ID:
 			return "#define UNIFORM_ID\n";
 
+		case GPU_SHADER_2D_UV_FACES_STRETCH_ANGLE:
+			return "#define STRETCH_ANGLE\n";
+
 		default:
 			return NULL;
 	}
diff --git a/source/blender/gpu/shaders/gpu_shader_2D_edituvs_stretch_vert.glsl b/source/blender/gpu/shaders/gpu_shader_2D_edituvs_stretch_vert.glsl
index 4588e41573b..c575e06ed3b 100644
--- a/source/blender/gpu/shaders/gpu_shader_2D_edituvs_stretch_vert.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_2D_edituvs_stretch_vert.glsl
@@ -1,8 +1,16 @@
 
 uniform mat4 ModelViewProjectionMatrix;
+uniform vec2 aspect;
 
 in vec2 pos;
+
+#ifndef STRETCH_ANGLE
 in float stretch;
+#else
+
+in vec4 uv_adj;
+in float angle;
+#endif
 
 noperspective out vec4 finalColor;
 
@@ -42,8 +50,30 @@ vec3 weight_to_rgb(float weight)
 	return r_rgb;
 }
 
+#define M_PI       3.1415926535897932
+
+/* Adapted from BLI_math_vector.h */
+float angle_normalized_v2v2(vec2 v1, vec2 v2)
+{
+	v1 = normalize(v1 * aspect);
+	v2 = normalize(v2 * aspect);
+	/* this is the same as acos(dot_v3v3(v1, v2)), but more accurate */
+	bool q = (dot(v1, v2) >= 0.0);
+	vec2 v = (q) ? (v1 - v2) : (v1 + v2);
+	float a = 2.0 * asin(length(v) / 2.0);
+	return (q) ? a : M_PI - a;
+}
+
 void main()
 {
 	gl_Position = ModelViewProjectionMatrix * vec4(pos, 0.0, 1.0);
+
+#ifdef STRETCH_ANGLE
+	float uv_angle = angle_normalized_v2v2(uv_adj.xy, uv_adj.zw) / M_PI;
+	float stretch = 1.0 - abs(uv_angle - angle);
+	stretch = stretch;
+	stretch = 1.0 - stretch * stretch;
+#endif
+
 	finalColor = vec4(weight_to_rgb(stretch), 1.0);
 }