limit bisectrice length in strokes, prevent oversized line joins, may…

… be more accurate
zshift · Sep 3, 2020 · 88ebe9f · 88ebe9f
1 parent ba1aef7
commit 88ebe9f
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Showing 3 changed files with 27 additions and 13 deletions.
diff --git a/src/vectors.c b/src/vectors.c
@@ -62,11 +62,18 @@ vec2d vec2d_norm(vec2d a)
 }
 // multiply 2d vector by scalar
 vec2d vec2d_mult(vec2d a, double m){
-	return (vec2d){a.x*m,a.y*m};
+    return (vec2d){a.x*m,a.y*m};
+}
+// devide 2d vector by scalar
+vec2 vec2_div(vec2 a, float m){
+    return (vec2){a.x/m,a.y/m};
+}
+vec2d vec2d_div(vec2d a, double m){
+    return (vec2d){a.x/m,a.y/m};
 }
 // multiply 2d vector by scalar
 vec2 vec2_mult(vec2 a, float m){
-	return (vec2){a.x*m,a.y*m};
+    return (vec2){a.x*m,a.y*m};
 }
 // compute perpendicular vector
 vec2d vec2d_perp (vec2d a){

diff --git a/src/vectors.h b/src/vectors.h
@@ -78,6 +78,7 @@ vec2		vec2_perp	(vec2 a);
 vec2		vec2_add	(vec2 a, vec2 b);
 vec2		vec2_sub	(vec2 a, vec2 b);
 vec2		vec2_mult	(vec2 a, float m);
+vec2		vec2_div	(vec2 a, float m);
 bool		vec2_equ	(vec2 a, vec2 b);
 vec2		vec2_line_norm	(vec2 a, vec2 b);
 bool        vec2_isnan  (vec2 v);
@@ -88,6 +89,7 @@ vec2d		vec2d_perp	(vec2d a);
 vec2d		vec2d_add	(vec2d a, vec2d b);
 vec2d		vec2d_sub	(vec2d a, vec2d b);
 vec2d		vec2d_mult	(vec2d a, double m);
+vec2d		vec2d_div	(vec2d a, double m);
 vec2d		vec2d_line_norm(vec2d a, vec2d b);
 bool        vec2d_isnan  (vec2d v);
 

diff --git a/src/vkvg_context_internal.c b/src/vkvg_context_internal.c
@@ -732,13 +732,14 @@ void _init_descriptor_sets (VkvgContext ctx){
 float _build_vb_step (vkvg_context* ctx, float hw, vec2 pL, vec2 p0, vec2 pR, bool isCurve){
 	Vertex v = {{0},ctx->curColor, {0,0,-1}};
 
-	//if two of the three points are equal, normal is null
-	vec2 v0n = vec2_line_norm(pL, p0);
-	if (vec2_isnan(v0n))
-		return 0;
-	vec2 v1n = vec2_line_norm(p0, pR);
-	if (vec2_isnan(v1n))
-		return 0;
+    vec2 v0 = vec2_sub(p0, pL);
+    vec2 v1 = vec2_sub(pR, p0);
+    float length_v0 = vec2_length(v0);
+    float length_v1 = vec2_length(v1);
+    if (length_v0 < FLT_EPSILON || length_v1 < FLT_EPSILON)
+        return 0;
+    vec2 v0n = vec2_div (v0, length_v0);
+    vec2 v1n = vec2_div (v1, length_v1);
 
 	vec2 bisec = vec2_norm(vec2_add(v0n,v1n));
 
@@ -751,16 +752,20 @@ float _build_vb_step (vkvg_context* ctx, float hw, vec2 pL, vec2 p0, vec2 pR, bo
 
 	float lh = hw / cosf(alpha);
 	bisec = vec2_perp(bisec);
+
+    //limit bisectrice lenght, may be improved but ok for perf
+    lh=fminf (lh, fminf (sqrtf(length_v0*length_v0+hw*hw), sqrtf(length_v1*length_v1+hw*hw)));
+
 	bisec = vec2_mult(bisec,lh);
 
 	VKVG_IBO_INDEX_TYPE idx = (VKVG_IBO_INDEX_TYPE)(ctx->vertCount - ctx->curVertOffset);
 
 	if (ctx->lineJoin == VKVG_LINE_JOIN_MITER || isCurve){
 		v.pos = vec2_add(p0, bisec);
 		_add_vertex(ctx, v);
-		v.pos = vec2_sub(p0, bisec);
-		_add_vertex(ctx, v);
-		_add_tri_indices_for_rect(ctx, idx);
+        v.pos = vec2_sub(p0, bisec);
+        _add_vertex(ctx, v);
+        _add_tri_indices_for_rect(ctx, idx);
 	}else{
 		vec2 vp = vec2_perp(v0n);
 		if (cross<0){
@@ -771,7 +776,7 @@ float _build_vb_step (vkvg_context* ctx, float hw, vec2 pL, vec2 p0, vec2 pR, bo
 			v.pos = vec2_add (p0, vec2_mult (vp, hw));
 			_add_vertex(ctx, v);
 			v.pos = vec2_sub (p0, bisec);
-		}
+        }
 		_add_vertex(ctx, v);
 
 		if (ctx->lineJoin == VKVG_LINE_JOIN_BEVEL){