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Ensure DrawSplineSegmentBezierCubicVar renders somewhat correctly

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Henry Wilder 2025-03-03 22:20:42 -05:00
commit efa7ef12e6
1 changed files with 125 additions and 50 deletions
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128
src/rshapes.c
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@ -2107,63 +2107,93 @@ void DrawSplineSegmentBezierCubic(Vector2 p1, Vector2 c2, Vector2 c3, Vector2 p4
DrawTriangleStrip(points, 2*SPLINE_SEGMENT_DIVISIONS + 2, color);
}
// Draw spline segment with variable thickness: Cubic Bezier, 2 points, 2 control points, 1 or more thickness
// Draw spline segment with variable thickness: Cubic Bezier, 2 points, 2 control points
void DrawSplineSegmentBezierCubicVar(Vector2 p1, Vector2 c2, Vector2 c3, Vector2 p4, const float* thicks, int thickCount, Color color)
{
if (thickCount >= 1)
if (thickCount >= 4)
{
const float step = 1.0f/SPLINE_SEGMENT_DIVISIONS;
rlBegin(RL_TRIANGLES);
rlColor4ub(color.r, color.g, color.b, color.a);
Vector2 previous = p1;
Vector2 current = { 0 };
float t = 0.0f;
const float step = 1.0f/SPLINE_SEGMENT_DIVISIONS;
Vector2 points[2*SPLINE_SEGMENT_DIVISIONS + 2] = { 0 };
Vector2 previous[2] = { 0 };
Vector2 current[2] = { 0 };
float t = 0.0f;
for (int i = 1; i <= SPLINE_SEGMENT_DIVISIONS; i++)
{
t = step*(float)i;
float thick;
if (thickCount > 1) {
float tMajor = t*(float)thickCount;
int tIndex = (int)tMajor;
if (tIndex >= thickCount) tIndex = thickCount - 1;
float tMinor = tMajor - (float)tIndex;
thick = thicks[tIndex];
} else {
thick = thicks[0]; // constant thickness
}
float a = powf(1.0f - t, 3);
float b = 3.0f*powf(1.0f - t, 2)*t;
float c = 3.0f*(1.0f - t)*powf(t, 2);
float d = powf(t, 3);
current.y = a*p1.y + b*c2.y + c*c3.y + d*p4.y;
current.x = a*p1.x + b*c2.x + c*c3.x + d*p4.x;
float dy = current.y - previous.y;
float dx = current.x - previous.x;
float size = 0.5f*thick/sqrtf(dx*dx+dy*dy);
if (i == 1)
for (int i = 0; i <= SPLINE_SEGMENT_DIVISIONS; i++)
{
points[0].x = previous.x + dy*size;
points[0].y = previous.y - dx*size;
points[1].x = previous.x - dy*size;
points[1].y = previous.y + dx*size;
t = step*(float)i;
Vector2 tangent = { 0 };
{
float a = 3.0f*powf(1.0f - t, 2);
float b = 6.0f*(1.0f - t)*t;
float c = 3.0f*t*t;
tangent.x = a*(c2.x - p1.x) + b*(c3.x - c2.x) + c*(p4.x - c3.x);
tangent.y = a*(c2.y - p1.y) + b*(c3.y - c2.y) + c*(p4.y - c3.y);
}
float speedSqr = (tangent.x*tangent.x + tangent.y*tangent.y);
if (speedSqr == 0) continue;
float speedInv = 1.0f/sqrtf(speedSqr);
tangent.x = tangent.x*speedInv;
tangent.y = tangent.y*speedInv;
Vector2 point = { 0 };
{
float a = powf(1.0f - t, 3);
float b = 3.0f*powf(1.0f - t, 2)*t;
float c = 3.0f*(1.0f - t)*powf(t, 2);
float d = powf(t, 3);
point.y = a*p1.y + b*c2.y + c*c3.y + d*p4.y;
point.x = a*p1.x + b*c2.x + c*c3.x + d*p4.x;
}
// TODO: Doesn't seem to be working properly for more than 3 distinct values
float thick;
{
float tMajor = t*(float)thickCount;
int tIndex = (int)tMajor;
float tMinor = tMajor - (float)tIndex;
tIndex *= 3;
if (tIndex >= thickCount - 3)
{
tIndex = thickCount - 4;
tMinor = 1.0f;
}
float a = powf(1.0f - t, 3);
float b = 3.0f*powf(1.0f - t, 2)*t;
float c = 3.0f*(1.0f - t)*t*t;
float d = t*t*t;
thick = a*thicks[tIndex] + b*thicks[tIndex + 1] + c*thicks[tIndex + 2] + d*thicks[tIndex + 3];
}
current[0].x = point.x + thick*tangent.y;
current[0].y = point.y - thick*tangent.x;
current[1].x = point.x - thick*tangent.y;
current[1].y = point.y + thick*tangent.x;
if (i > 0)
{
rlVertex2f(current[0].x, current[0].y);
rlVertex2f(previous[0].x, previous[0].y);
rlVertex2f(previous[1].x, previous[1].y);
rlVertex2f(current[1].x, current[1].y);
rlVertex2f(current[0].x, current[0].y);
rlVertex2f(previous[1].x, previous[1].y);
}
previous[0] = current[0];
previous[1] = current[1];
}
points[2*i + 1].x = current.x - dy*size;
points[2*i + 1].y = current.y + dx*size;
points[2*i].x = current.x + dy*size;
points[2*i].y = current.y - dx*size;
previous = current;
}
DrawTriangleStrip(points, 2*SPLINE_SEGMENT_DIVISIONS + 2, color);
rlEnd();
}
}
@ -2576,7 +2606,7 @@ float GetSplineCurvatureBezierCubic(Vector2 startPos, Vector2 startControlPos, V
acceleration.x = a*(endControlPos.x - 2.0f*startControlPos.x + startPos.x) + b*(endPos.x - 2.0f*endControlPos.x + startControlPos.x);
acceleration.y = a*(endControlPos.y - 2.0f*startControlPos.y + startPos.y) + b*(endPos.y - 2.0f*endControlPos.y + startControlPos.y);
float curvature = (velocity.x*acceleration.y - velocity.y*acceleration.x)/powf(sqrtf(velocity.x*velocity.x + velocity.y*velocity.y), 3);
curvature = (velocity.x*acceleration.y - velocity.y*acceleration.x)/powf(sqrtf(velocity.x*velocity.x + velocity.y*velocity.y), 3);
return curvature;
}