Reworked version of dashed line shader.

Using geometry shader allows us to get rid of the 'line origin' extra
vertex attribute, which means dashed shader no longer requires fiddling
with those vertex attributes definition, and, most importantly, does not
require anymore special drawing code!

As you can see, this makes code much simpler, and much less verbose,
especially in complex cases.

In addition, changed how dashes are handled, to have two 'modes', a
simple one with single color (using default "color" uniform name), and a
more advanced one allowing more complex and multi-color patterns.

Note that since GLSL 1.2 does not support geometry shaders, a hack was
added for now (which gives solid lines, but at least does not make
Blender crash).

1 files changed, 34 insertions, 71 deletions

diff --git a/source/blender/editors/uvedit/uvedit_draw.c b/source/blender/editors/uvedit/uvedit_draw.c
index 53b2bd1ae67..3dc6ed8194b 100644
--- a/source/blender/editors/uvedit/uvedit_draw.c
+++ b/source/blender/editors/uvedit/uvedit_draw.c
@@ -71,8 +71,7 @@
 
 #include "uvedit_intern.h"
 
-static void draw_uvs_lineloop_bmface(
-        BMFace *efa, const int cd_loop_uv_offset, uint shdr_pos, const bool use_dashed, uint shdr_dashed_origin);
+static void draw_uvs_lineloop_bmface(BMFace *efa, const int cd_loop_uv_offset, const uint shdr_pos);
 
 void ED_image_draw_cursor(ARegion *ar, const float cursor[2])
 {
@@ -86,9 +85,7 @@ void ED_image_draw_cursor(ARegion *ar, const float cursor[2])
 
 	gpuTranslate2fv(cursor);
 
-	VertexFormat *format = immVertexFormat();
-	uint shdr_dashed_pos = VertexFormat_add_attrib(format, "pos", COMP_F32, 2, KEEP_FLOAT);
-	uint shdr_dashed_origin = VertexFormat_add_attrib(format, "line_origin", COMP_F32, 2, KEEP_FLOAT);
+	const uint shdr_pos = VertexFormat_add_attrib(immVertexFormat(), "pos", COMP_F32, 2, KEEP_FLOAT);
 
 	immBindBuiltinProgram(GPU_SHADER_2D_LINE_DASHED_COLOR);
 
@@ -96,53 +93,42 @@ void ED_image_draw_cursor(ARegion *ar, const float cursor[2])
 	glGetFloatv(GL_VIEWPORT, viewport_size);
 	immUniform2f("viewport_size", viewport_size[2] / UI_DPI_FAC, viewport_size[3] / UI_DPI_FAC);
 
-	immUniform4f("color1", 1.0f, 0.0f, 0.0f, 1.0f);
-	immUniform4f("color2", 1.0f, 1.0f, 1.0f, 1.0f);
+	immUniform1i("num_colors", 2);  /* "advanced" mode */
+	immUniformArray4fv("colors", (float *)(float[][4]){{1.0f, 0.0f, 0.0f, 1.0f}, {1.0f, 1.0f, 1.0f, 1.0f}}, 2);
 	immUniform1f("dash_width", 8.0f);
-	immUniform1f("dash_width_on", 4.0f);
 
 	immBegin(PRIM_LINES, 8);
 
-	immAttrib2f(shdr_dashed_origin, -0.05f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, -0.05f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, 0.0f, 0.05f * y_fac);
+	immVertex2f(shdr_pos, -0.05f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, 0.0f, 0.05f * y_fac);
 
-	immAttrib2f(shdr_dashed_origin, 0.0f, 0.05f * y_fac);
-	immVertex2f(shdr_dashed_pos, 0.0f, 0.05f * y_fac);
-	immVertex2f(shdr_dashed_pos, 0.05f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, 0.0f, 0.05f * y_fac);
+	immVertex2f(shdr_pos, 0.05f * x_fac, 0.0f);
 
-	immAttrib2f(shdr_dashed_origin, 0.05f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, 0.05f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, 0.0f, -0.05f * y_fac);
+	immVertex2f(shdr_pos, 0.05f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, 0.0f, -0.05f * y_fac);
 
-	immAttrib2f(shdr_dashed_origin, 0.0f, -0.05f * y_fac);
-	immVertex2f(shdr_dashed_pos, 0.0f, -0.05f * y_fac);
-	immVertex2f(shdr_dashed_pos, -0.05f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, 0.0f, -0.05f * y_fac);
+	immVertex2f(shdr_pos, -0.05f * x_fac, 0.0f);
 
 	immEnd();
 
-	immUniform4f("color1", 1.0f, 1.0f, 1.0f, 1.0f);
-	immUniform4f("color2", 0.0f, 0.0f, 0.0f, 1.0f);
+	immUniformArray4fv("colors", (float *)(float[][4]){{1.0f, 1.0f, 1.0f, 1.0f}, {0.0f, 0.0f, 0.0f, 1.0f}}, 2);
 	immUniform1f("dash_width", 2.0f);
-	immUniform1f("dash_width_on", 1.0f);
 
 	immBegin(PRIM_LINES, 8);
 
-	immAttrib2f(shdr_dashed_origin, -0.020f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, -0.020f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, -0.1f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, -0.020f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, -0.1f * x_fac, 0.0f);
 
-	immAttrib2f(shdr_dashed_origin, 0.1f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, 0.1f * x_fac, 0.0f);
-	immVertex2f(shdr_dashed_pos, 0.020f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, 0.1f * x_fac, 0.0f);
+	immVertex2f(shdr_pos, 0.020f * x_fac, 0.0f);
 
-	immAttrib2f(shdr_dashed_origin, 0.0f, -0.020f * y_fac);
-	immVertex2f(shdr_dashed_pos, 0.0f, -0.020f * y_fac);
-	immVertex2f(shdr_dashed_pos, 0.0f, -0.1f * y_fac);
+	immVertex2f(shdr_pos, 0.0f, -0.020f * y_fac);
+	immVertex2f(shdr_pos, 0.0f, -0.1f * y_fac);
 
-	immAttrib2f(shdr_dashed_origin, 0.0f, 0.1f * y_fac);
-	immVertex2f(shdr_dashed_pos, 0.0f, 0.1f * y_fac);
-	immVertex2f(shdr_dashed_pos, 0.0f, 0.020f * y_fac);
+	immVertex2f(shdr_pos, 0.0f, 0.1f * y_fac);
+	immVertex2f(shdr_pos, 0.0f, 0.020f * y_fac);
 
 	immEnd();
 
@@ -185,7 +171,7 @@ static void draw_uvs_shadow(Object *obedit)
 	immUniformThemeColor(TH_UV_SHADOW);
 
 	BM_ITER_MESH (efa, &iter, bm, BM_FACES_OF_MESH) {
-		draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos, false, 0);
+		draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos);
 	}
 
 	immUnbindProgram();
@@ -400,37 +386,17 @@ static void draw_uvs_stretch(SpaceImage *sima, Scene *scene, BMEditMesh *em, MTe
 	BLI_buffer_free(&tf_uvorig_buf);
 }
 
-static void draw_uvs_lineloop_bmface(
-        BMFace *efa, const int cd_loop_uv_offset, uint shdr_pos, const bool use_dashed, uint shdr_dashed_origin)
+static void draw_uvs_lineloop_bmface(BMFace *efa, const int cd_loop_uv_offset, const uint shdr_pos)
 {
 	BMIter liter;
 	BMLoop *l;
 	MLoopUV *luv;
 
-	if (use_dashed) {
-		immBegin(PRIM_LINES, efa->len * 2);
+	immBegin(PRIM_LINE_LOOP, efa->len);
 
-		const float *prev_uv = NULL;
-		BM_ITER_ELEM (l, &liter, efa, BM_LOOPS_OF_FACE) {
-			if (prev_uv == NULL) {
-				luv = BM_ELEM_CD_GET_VOID_P(l->prev, cd_loop_uv_offset);
-				prev_uv = luv->uv;
-			}
-			luv = BM_ELEM_CD_GET_VOID_P(l, cd_loop_uv_offset);
-
-			immAttrib2fv(shdr_dashed_origin, prev_uv);
-			immVertex2fv(shdr_pos, prev_uv);
-			immVertex2fv(shdr_pos, luv->uv);
-			prev_uv = luv->uv;
-		}
-	}
-	else {
-		immBegin(PRIM_LINE_LOOP, efa->len);
-
-		BM_ITER_ELEM (l, &liter, efa, BM_LOOPS_OF_FACE) {
-			luv = BM_ELEM_CD_GET_VOID_P(l, cd_loop_uv_offset);
-			immVertex2fv(shdr_pos, luv->uv);
-		}
+	BM_ITER_ELEM (l, &liter, efa, BM_LOOPS_OF_FACE) {
+		luv = BM_ELEM_CD_GET_VOID_P(l, cd_loop_uv_offset);
+		immVertex2fv(shdr_pos, luv->uv);
 	}
 
 	immEnd();
@@ -770,9 +736,7 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, SceneLayer *sl, Object *obe
 	switch (sima->dt_uv) {
 		case SI_UVDT_DASH:
 		{
-			VertexFormat *format = immVertexFormat();
-			uint shdr_dashed_pos = VertexFormat_add_attrib(format, "pos", COMP_F32, 2, KEEP_FLOAT);
-			uint shdr_dashed_origin = VertexFormat_add_attrib(format, "line_origin", COMP_F32, 2, KEEP_FLOAT);
+			const uint shdr_pos = VertexFormat_add_attrib(immVertexFormat(), "pos", COMP_F32, 2, KEEP_FLOAT);
 
 			immBindBuiltinProgram(GPU_SHADER_2D_LINE_DASHED_COLOR);
 
@@ -780,10 +744,9 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, SceneLayer *sl, Object *obe
 			glGetFloatv(GL_VIEWPORT, viewport_size);
 			immUniform2f("viewport_size", viewport_size[2] / UI_DPI_FAC, viewport_size[3] / UI_DPI_FAC);
 
-			immUniform4f("color1", 0.56f, 0.56f, 0.56f, 1.0f);
-			immUniform4f("color2", 0.07f, 0.07f, 0.07f, 1.0f);
+			immUniform1i("num_colors", 2);  /* "advanced" mode */
+			immUniformArray4fv("colors", (float *)(float[][4]){{0.56f, 0.56f, 0.56f, 1.0f}, {0.07f, 0.07f, 0.07f, 1.0f}}, 2);
 			immUniform1f("dash_width", 4.0f);
-			immUniform1f("dash_width_on", 2.0f);
 
 			BM_ITER_MESH (efa, &iter, bm, BM_FACES_OF_MESH) {
 				if (!BM_elem_flag_test(efa, BM_ELEM_TAG))
@@ -791,7 +754,7 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, SceneLayer *sl, Object *obe
 				tf = BM_ELEM_CD_GET_VOID_P(efa, cd_poly_tex_offset);
 
 				if (tf) {
-					draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, shdr_dashed_pos, true, shdr_dashed_origin);
+					draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, shdr_pos);
 				}
 			}
 
@@ -816,7 +779,7 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, SceneLayer *sl, Object *obe
 				if (!BM_elem_flag_test(efa, BM_ELEM_TAG))
 					continue;
 
-				draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos, false, 0);
+				draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos);
 			}
 
 			immUnbindProgram();
@@ -834,7 +797,7 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, SceneLayer *sl, Object *obe
 				if (!BM_elem_flag_test(efa, BM_ELEM_TAG))
 					continue;
 
-				draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos, false, 0);
+				draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos);
 			}
 
 			immUnbindProgram();
@@ -913,7 +876,7 @@ static void draw_uvs(SpaceImage *sima, Scene *scene, SceneLayer *sl, Object *obe
 					if (!BM_elem_flag_test(efa, BM_ELEM_TAG))
 						continue;
 				
-					draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos, false, 0);
+					draw_uvs_lineloop_bmface(efa, cd_loop_uv_offset, pos);
 				}
 
 				immUnbindProgram();