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, 27 insertions, 42 deletions

diff --git a/source/blender/editors/space_view3d/view3d_ruler.c b/source/blender/editors/space_view3d/view3d_ruler.c
index 9bdc75802ba..aecde1b1657 100644
--- a/source/blender/editors/space_view3d/view3d_ruler.c
+++ b/source/blender/editors/space_view3d/view3d_ruler.c
@@ -458,38 +458,30 @@ static void ruler_info_draw_pixel(const struct bContext *C, ARegion *ar, void *a
 
 		glEnable(GL_BLEND);
 
-		if (ruler_item->flag & RULERITEM_USE_ANGLE) {
-			VertexFormat *format = immVertexFormat();
-			uint pos = VertexFormat_add_attrib(format, "pos", COMP_F32, 2, KEEP_FLOAT);
-			uint line_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);
 
+		if (ruler_item->flag & RULERITEM_USE_ANGLE) {
 			immBindBuiltinProgram(GPU_SHADER_2D_LINE_DASHED_COLOR);
 
 			float viewport_size[4];
 			glGetFloatv(GL_VIEWPORT, viewport_size);
 			immUniform2f("viewport_size", viewport_size[2], viewport_size[3]);
 
-			immUniform4f("color1", 0.67f, 0.67f, 0.67f, 1.0f);
-			immUniform4fv("color2", is_act ? color_act : color_base);
+			immUniform1i("num_colors", 2);  /* "advanced" mode */
+			const float *col = is_act ? color_act : color_base;
+			immUniformArray4fv("colors", (float *)(float[][4]){{0.67f, 0.67f, 0.67f, 1.0f}, {col[0], col[1], col[2], col[3]}}, 2);
 			immUniform1f("dash_width", 6.0f);
-			immUniform1f("dash_width_on", 3.0f);
-
-			immBegin(PRIM_LINES, 4);
 
-			immAttrib2fv(line_origin, co_ss[0]);
-			immVertex2fv(pos, co_ss[0]);
-			immVertex2fv(pos, co_ss[1]);
+			immBegin(PRIM_LINE_STRIP, 3);
 
-			immAttrib2fv(line_origin, co_ss[1]);
-			immVertex2fv(pos, co_ss[1]);
-			immVertex2fv(pos, co_ss[2]);
+			immVertex2fv(shdr_pos, co_ss[0]);
+			immVertex2fv(shdr_pos, co_ss[1]);
+			immVertex2fv(shdr_pos, co_ss[2]);
 
 			immEnd();
 
 			immUnbindProgram();
 
-			pos = VertexFormat_add_attrib(immVertexFormat(), "pos", COMP_F32, 2, KEEP_FLOAT);
-
 			immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
 
 			/* arc */
@@ -529,7 +521,7 @@ static void ruler_info_draw_pixel(const struct bContext *C, ARegion *ar, void *a
 					ED_view3d_project_float_global(ar, co_tmp, arc_ss_coord, V3D_PROJ_TEST_NOP);
 					mul_qt_v3(quat, dir_tmp);
 
-					immVertex2fv(pos, arc_ss_coord);
+					immVertex2fv(shdr_pos, arc_ss_coord);
 				}
 
 				immEnd();
@@ -558,20 +550,20 @@ static void ruler_info_draw_pixel(const struct bContext *C, ARegion *ar, void *a
 				immBegin(PRIM_LINES, 8);
 
 				madd_v2_v2v2fl(cap, co_ss[0], rot_90_vec_a, cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 				madd_v2_v2v2fl(cap, co_ss[0], rot_90_vec_a, -cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 
 				madd_v2_v2v2fl(cap, co_ss[2], rot_90_vec_b, cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 				madd_v2_v2v2fl(cap, co_ss[2], rot_90_vec_b, -cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 
 				/* angle vertex */
-				immVertex2f(pos, co_ss[1][0] - cap_size, co_ss[1][1] - cap_size);
-				immVertex2f(pos, co_ss[1][0] + cap_size, co_ss[1][1] + cap_size);
-				immVertex2f(pos, co_ss[1][0] - cap_size, co_ss[1][1] + cap_size);
-				immVertex2f(pos, co_ss[1][0] + cap_size, co_ss[1][1] - cap_size);
+				immVertex2f(shdr_pos, co_ss[1][0] - cap_size, co_ss[1][1] - cap_size);
+				immVertex2f(shdr_pos, co_ss[1][0] + cap_size, co_ss[1][1] + cap_size);
+				immVertex2f(shdr_pos, co_ss[1][0] - cap_size, co_ss[1][1] + cap_size);
+				immVertex2f(shdr_pos, co_ss[1][0] + cap_size, co_ss[1][1] - cap_size);
 
 				immEnd();
 
@@ -608,33 +600,26 @@ static void ruler_info_draw_pixel(const struct bContext *C, ARegion *ar, void *a
 			}
 		}
 		else {
-			VertexFormat *format = immVertexFormat();
-			uint pos = VertexFormat_add_attrib(format, "pos", COMP_F32, 2, KEEP_FLOAT);
-			uint line_origin = VertexFormat_add_attrib(format, "line_origin", COMP_F32, 2, KEEP_FLOAT);
-
 			immBindBuiltinProgram(GPU_SHADER_2D_LINE_DASHED_COLOR);
 
 			float viewport_size[4];
 			glGetFloatv(GL_VIEWPORT, viewport_size);
 			immUniform2f("viewport_size", viewport_size[2], viewport_size[3]);
 
-			immUniform4f("color1", 0.67f, 0.67f, 0.67f, 1.0f);
-			immUniform4fv("color2", is_act ? color_act : color_base);
+			immUniform1i("num_colors", 2);  /* "advanced" mode */
+			const float *col = is_act ? color_act : color_base;
+			immUniformArray4fv("colors", (float *)(float[][4]){{0.67f, 0.67f, 0.67f, 1.0f}, {col[0], col[1], col[2], col[3]}}, 2);
 			immUniform1f("dash_width", 6.0f);
-			immUniform1f("dash_width_on", 3.0f);
 
 			immBegin(PRIM_LINES, 2);
 
-			immAttrib2fv(line_origin, co_ss[0]);
-			immVertex2fv(pos, co_ss[0]);
-			immVertex2fv(pos, co_ss[2]);
+			immVertex2fv(shdr_pos, co_ss[0]);
+			immVertex2fv(shdr_pos, co_ss[2]);
 
 			immEnd();
 
 			immUnbindProgram();
 
-			pos = VertexFormat_add_attrib(immVertexFormat(), "pos", COMP_F32, 2, KEEP_FLOAT);
-
 			immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
 
 			sub_v2_v2v2(dir_ruler, co_ss[0], co_ss[2]);
@@ -653,14 +638,14 @@ static void ruler_info_draw_pixel(const struct bContext *C, ARegion *ar, void *a
 				immBegin(PRIM_LINES, 4);
 
 				madd_v2_v2v2fl(cap, co_ss[0], rot_90_vec, cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 				madd_v2_v2v2fl(cap, co_ss[0], rot_90_vec, -cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 
 				madd_v2_v2v2fl(cap, co_ss[2], rot_90_vec, cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 				madd_v2_v2v2fl(cap, co_ss[2], rot_90_vec, -cap_size);
-				immVertex2fv(pos, cap);
+				immVertex2fv(shdr_pos, cap);
 
 				immEnd();