build_vb_step seems ok, code may be simplified, still one limit case

diff --git a/src/vkvg_context_internal.c b/src/vkvg_context_internal.c
index c791ce00d20142a504847403251476f792a402ff..87002b80f0e411859db905557ae79335af322e9b 100644 (file)
--- a/src/vkvg_context_internal.c
+++ b/src/vkvg_context_internal.c
@@ -1,4 +1,4 @@
-/*
+/*
  * Copyright (c) 2018 Jean-Philippe Bruyère <jp_bruyere@hotmail.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
@@ -792,14 +792,13 @@ bool _build_vb_step (vkvg_context* ctx, float hw, stroke_context_t* str, bool is
        float halfAlpha = alpha / 2.f;
 
        float lh = hw / cosf(halfAlpha);
-       bisec_n = vec2_perp(bisec_n);
+       vec2 bisec_n_perp = vec2_perp(bisec_n);
 
        //limit bisectrice length
-       bool reducedLH = EQUF(dot,-1) || (lh > fminf (lh, fminf (length_v0, length_v1)));
        float rlh = fminf (lh, fminf (length_v0, length_v1));
        //---
 
-       vec2 bisec = vec2_mult_s (bisec_n, rlh);
+       vec2 bisec = vec2_mult_s (bisec_n_perp, rlh);
 
        VKVG_IBO_INDEX_TYPE idx = (VKVG_IBO_INDEX_TYPE)(ctx->vertCount - ctx->curVertOffset);
 
@@ -807,7 +806,7 @@ bool _build_vb_step (vkvg_context* ctx, float hw, stroke_context_t* str, bool is
                if (dot < 0.f && rlh < lh) {
                        double x = (lh - rlh) * cosf (halfAlpha);
                        double lbc = cosf(halfAlpha) * rlh;
-                       vec2 bisecPerp = vec2_mult_s (vec2_perp(bisec_n), x);
+                       vec2 bisecPerp = vec2_mult_s (bisec_n, x);
                        vec2 vnPerp;
                        if (length_v0 < length_v1)
                                vnPerp = vec2_perp (v1n);
@@ -817,13 +816,13 @@ bool _build_vb_step (vkvg_context* ctx, float hw, stroke_context_t* str, bool is
                        vec2 p = vec2_add(p0, bisec);
 
                        if (det > 0) {
-                               v.pos = vec2_add(p, bisecPerp);
+                               v.pos = vec2_sub(p, bisecPerp);
                                _add_vertex(ctx, v);
 
                                v.pos = vec2_sub (vec2_add (vec2_mult_s(vnPerp, lbc), vec2_sub(p0, bisec)), vHwPerp);
                                _add_vertex(ctx, v);
 
-                               v.pos = vec2_sub(p, bisecPerp);
+                               v.pos = vec2_add(p, bisecPerp);
                                _add_vertex(ctx, v);
 
                                _add_triangle_indices(ctx, idx, idx+2, idx+1);
@@ -836,10 +835,10 @@ bool _build_vb_step (vkvg_context* ctx, float hw, stroke_context_t* str, bool is
 
                                p = vec2_sub(p0, bisec);
 
-                               v.pos = vec2_add(p, bisecPerp);
-                               _add_vertex(ctx, v);
                                v.pos = vec2_sub(p, bisecPerp);
                                _add_vertex(ctx, v);
+                               v.pos = vec2_add(p, bisecPerp);
+                               _add_vertex(ctx, v);
 
                                _add_triangle_indices(ctx, idx, idx+2, idx+1);
                                _add_triangle_indices(ctx, idx+2, idx+4, idx);
@@ -858,42 +857,47 @@ bool _build_vb_step (vkvg_context* ctx, float hw, stroke_context_t* str, bool is
                }
        }else{
                vec2 vp = vec2_perp(v0n);
+
                if (det<0){
-                       if (dot < 0 && reducedLH)
-                               v.pos = vec2_sub (p0, vec2_mult_s (vec2_perp(v1n), hw));
-                       else
+                       if (dot < 0 && rlh < lh) {
+                               vec2 vnPerp;
+                               if (length_v0 < length_v1)
+                                       vnPerp = vec2_perp (v1n);
+                               else
+                                       vnPerp = vec2_perp (v0n);
+                               vec2 vHwPerp = vec2_mult_s(vnPerp, hw);
+                               double lbc = cosf(halfAlpha) * rlh;
+                               v.pos = vec2_add (vec2_add (vec2_mult_s(vnPerp, -lbc), vec2_add(p0, bisec)), vHwPerp);
+                       } else
                                v.pos = vec2_add (p0, bisec);
                        _add_vertex(ctx, v);
                        v.pos = vec2_sub (p0, vec2_mult_s (vp, hw));
                }else{
                        v.pos = vec2_add (p0, vec2_mult_s (vp, hw));
                        _add_vertex(ctx, v);
-                       if (dot < 0 && reducedLH)
-                               v.pos = vec2_add (p0, vec2_mult_s (vec2_perp(v1n), hw));
-                       else
+                       if (dot < 0 && rlh < lh) {
+                               vec2 vnPerp;
+                               if (length_v0 < length_v1)
+                                       vnPerp = vec2_perp (v1n);
+                               else
+                                       vnPerp = vec2_perp (v0n);
+                               vec2 vHwPerp = vec2_mult_s(vnPerp, hw);
+                               double lbc = cosf(halfAlpha) * rlh;
+                               v.pos = vec2_sub (vec2_add (vec2_mult_s(vnPerp, lbc), vec2_sub(p0, bisec)), vHwPerp);
+                       }else
                                v.pos = vec2_sub (p0, bisec);
                }
                _add_vertex(ctx, v);
 
                if (ctx->lineJoin == VKVG_LINE_JOIN_BEVEL){
                        if (det<0){
-                               if (dot < 0 && reducedLH) {
-                                       _add_triangle_indices(ctx, idx, idx+3, idx+4);
-                                       _add_triangle_indices(ctx, idx+1, idx+3, idx+0);
-                               }else{
-                                       _add_triangle_indices(ctx, idx, idx+2, idx+1);
-                                       _add_triangle_indices(ctx, idx+2, idx+4, idx+0);
-                                       _add_triangle_indices(ctx, idx, idx+3, idx+4);
-                               }
+                               _add_triangle_indices(ctx, idx, idx+2, idx+1);
+                               _add_triangle_indices(ctx, idx+2, idx+4, idx+0);
+                               _add_triangle_indices(ctx, idx, idx+3, idx+4);
                        }else{
-                               if (dot < 0 && reducedLH) {
-                                       _add_triangle_indices(ctx, idx+1, idx+3, idx+4);
-                                       _add_triangle_indices(ctx, idx, idx+1, idx+4);
-                               }else{
-                                       _add_triangle_indices(ctx, idx, idx+2, idx+1);
-                                       _add_triangle_indices(ctx, idx+2, idx+3, idx+1);
-                                       _add_triangle_indices(ctx, idx+1, idx+3, idx+4);
-                               }
+                               _add_triangle_indices(ctx, idx, idx+2, idx+1);
+                               _add_triangle_indices(ctx, idx+2, idx+3, idx+1);
+                               _add_triangle_indices(ctx, idx+1, idx+3, idx+4);
                        }
                }else if (ctx->lineJoin == VKVG_LINE_JOIN_ROUND){
                        float step = M_PIF / hw;
@@ -920,29 +924,15 @@ bool _build_vb_step (vkvg_context* ctx, float hw, stroke_context_t* str, bool is
                        VKVG_IBO_INDEX_TYPE p0Idx = (VKVG_IBO_INDEX_TYPE)(ctx->vertCount - ctx->curVertOffset);
                        _add_triangle_indices(ctx, idx, idx+2, idx+1);
                        if (det < 0){
-                               if (dot < 0 && reducedLH) {
-                                       for (VKVG_IBO_INDEX_TYPE p = idx+2; p < p0Idx; p++)
-                                               _add_triangle_indices(ctx, p, p+1, idx);
-                                       _add_triangle_indices(ctx, idx+1, p0Idx+1, idx);
-                                       _add_triangle_indices(ctx, idx, p0Idx+1, p0Idx+2);
-                               }else{
-                                       for (VKVG_IBO_INDEX_TYPE p = idx+2; p < p0Idx; p++)
-                                               _add_triangle_indices(ctx, p, p+1, idx);
-                                       _add_triangle_indices(ctx, p0Idx, p0Idx+2, idx);
-                                       _add_triangle_indices(ctx, idx, p0Idx+1, p0Idx+2);
-                               }
+                               for (VKVG_IBO_INDEX_TYPE p = idx+2; p < p0Idx; p++)
+                                       _add_triangle_indices(ctx, p, p+1, idx);
+                               _add_triangle_indices(ctx, p0Idx, p0Idx+2, idx);
+                               _add_triangle_indices(ctx, idx, p0Idx+1, p0Idx+2);
                        }else{
-                               if (dot < 0 && reducedLH) {
-                                       for (VKVG_IBO_INDEX_TYPE p = idx+2; p < p0Idx; p++)
-                                               _add_triangle_indices(ctx, p, p+1, idx+1);
-                                       _add_triangle_indices(ctx, idx, p0Idx+2, idx+1);
-                                       _add_triangle_indices(ctx, idx+1, p0Idx+1, p0Idx+2);
-                               }else{
-                                       for (VKVG_IBO_INDEX_TYPE p = idx+2; p < p0Idx; p++)
-                                               _add_triangle_indices(ctx, p, p+1, idx+1);
-                                       _add_triangle_indices(ctx, p0Idx, p0Idx+1, idx+1);
-                                       _add_triangle_indices(ctx, idx+1, p0Idx+1, p0Idx+2);
-                               }
+                               for (VKVG_IBO_INDEX_TYPE p = idx+2; p < p0Idx; p++)
+                                       _add_triangle_indices(ctx, p, p+1, idx+1);
+                               _add_triangle_indices(ctx, p0Idx, p0Idx+1, idx+1);
+                               _add_triangle_indices(ctx, idx+1, p0Idx+1, p0Idx+2);
                        }
 
                }