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@@ -59,9 +59,9 @@ Bézier curves are polynomials of <i>t</i>, rather than <i>x</i>, with the value
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\[
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\begin{aligned}
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linear &= (1-t) + t \\
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square &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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cubic &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\textit{linear} &= (1-t) + t \\
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\textit{square} &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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\textit{cubic} &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\end{aligned}
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\]
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@@ -69,10 +69,10 @@ I know what you're thinking: that doesn't look too simple! But if we remove <i>t
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\[
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\begin{aligned}
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linear &= \hspace{2.5em} 1 + 1 \\
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square &= \hspace{1.7em} 1 + 2 + 1\\
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cubic &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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quartic &= 1 + 4 + 6 + 4 + 1
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\textit{linear} &= \hspace{2.5em} 1 + 1 \\
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\textit{square} &= \hspace{1.7em} 1 + 2 + 1\\
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\textit{cubic} &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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\textit{quartic} &= 1 + 4 + 6 + 4 + 1
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\end{aligned}
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\]
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@@ -82,19 +82,19 @@ There's an equally simple way to figure out how the polynomial terms work: if we
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\[
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\begin{aligned}
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linear &= BLUE[a] + RED[b] \\
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square &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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cubic &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\textit{linear} &= BLUE[a] + RED[b] \\
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\textit{square} &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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\textit{cubic} &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\end{aligned}
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\]
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It's basically just a sum of "every combination of <i>a</i> and <i>b</i>", progressively replacing <i>a</i>'s with <i>b</i>'s after every + sign. So that's actually pretty simple too. So now you know binomial polynomials, and just for completeness I'm going to show you the generic function for this:
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\[
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Bézier(n,t) = \sum_{i=0}^{n}
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\underset{binomial~term}{\underbrace{\binom{n}{i}}}
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\textit{Bézier}(n,t) = \sum_{i=0}^{n}
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\underset{\textit{binomial term}}{\underbrace{\binom{n}{i}}}
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\cdot\
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\underset{polynomial~term}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\underset{\textit{polynomial term}}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\]
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And that's the full description for Bézier curves. Σ in this function indicates that this is a series of additions (using the variable listed below the Σ, starting at ...=<value> and ending at the value listed on top of the Σ).
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@@ -57,9 +57,9 @@
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\[
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\begin{aligned}
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1次 &= (1-t) + t \\
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2次 &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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3次 &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\textit{1次} &= (1-t) + t \\
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\textit{2次} &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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\textit{3次} &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\end{aligned}
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\]
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@@ -67,10 +67,10 @@
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\[
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\begin{aligned}
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1次 &= \hspace{2.5em} 1 + 1 \\
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2次 &= \hspace{1.7em} 1 + 2 + 1\\
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3次 &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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4次 &= 1 + 4 + 6 + 4 + 1
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\textit{1次} &= \hspace{2.5em} 1 + 1 \\
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\textit{2次} &= \hspace{1.7em} 1 + 2 + 1\\
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\textit{3次} &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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\textit{4次} &= 1 + 4 + 6 + 4 + 1
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\end{aligned}
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\]
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@@ -80,19 +80,19 @@
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\[
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\begin{aligned}
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1次 &= BLUE[a] + RED[b] \\
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2次 &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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3次 &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\textit{1次} &= BLUE[a] + RED[b] \\
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\textit{2次} &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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\textit{3次} &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\end{aligned}
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\]
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これは要するに、「<i>a</i>と<i>b</i>のすべての組み合わせ」の単なる和です。プラスが出てくるたびに、<i>a</i>を<i>b</i>へと1つずつ置き換えていけばよいのです。こちらも本当に単純です。さて、これで「二項係数多項式」がわかりました。完璧を期するため、この関数の一般の形を示しておきます。
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\[
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Bézier(n,t) = \sum_{i=0}^{n}
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\underset{二項係数部分の項}{\underbrace{\binom{n}{i}}}
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\textit{Bézier}(n,t) = \sum_{i=0}^{n}
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\underset{\textit{二項係数部分の項}}{\underbrace{\binom{n}{i}}}
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\cdot\
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\underset{多項式部分の項}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\underset{\textit{多項式部分の項}}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\]
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そして、これがベジエ曲線の完全な表現です。この関数中のΣは、加算の繰り返し(Σの下にある変数を使って、...=<値>から始めてΣの下にある値まで)を表します。
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@@ -59,9 +59,9 @@
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\[
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\begin{aligned}
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линейный &= (1-t) + t \\
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квадратный &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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кубический &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\textit{линийный} &= (1-t) + t \\
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\textit{квадратый} &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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\textit{кубический} &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\end{aligned}
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\]
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@@ -69,10 +69,10 @@
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\[
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\begin{aligned}
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линийный &= \hspace{2.5em} 1 + 1 \\
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квадратый &= \hspace{1.7em} 1 + 2 + 1\\
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кубический &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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квартический &= 1 + 4 + 6 + 4 + 1
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\textit{линийный} &= \hspace{2.5em} 1 + 1 \\
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\textit{квадратый} &= \hspace{1.7em} 1 + 2 + 1\\
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\textit{кубический} &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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\textit{квартический} &= 1 + 4 + 6 + 4 + 1
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\end{aligned}
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\]
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@@ -82,19 +82,19 @@
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\[
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\begin{aligned}
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линийный &= BLUE[a] + RED[b] \\
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квадратый &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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кубический &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\textit{линийный} &= BLUE[a] + RED[b] \\
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\textit{квадратый} &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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\textit{кубический} &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\end{aligned}
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\]
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В целом это просто сума "каждого сочетания <i>a</i> и <i>b</i>", получаемая прогрессивной заменой <i>a</i> на <i>b</i> по ходу уравнения. Потому, это так-же довольно просто. Итак теперь вы знаете что такое биноминальные полиномы. Для полноты картины, ниже привожу их общую функцию:
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\[
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Bézier(n,t) = \sum_{i=0}^{n}
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\underset{биноминальный~термин}{\underbrace{\binom{n}{i}}}
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\textit{Bézier}(n,t) = \sum_{i=0}^{n}
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\underset{\textit{биноминальный термин}}{\underbrace{\binom{n}{i}}}
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\cdot\
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\underset{полиноминальный~термин}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\underset{\textit{полиноминальный термин}}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\]
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И теперь, это полное объяснение. Σ в этой функции означает, что это серия сум (с использованием переменной приведенной под Σ, со стартовым значением в ...=<value> и максимальным значением представленным над Σ)
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@@ -57,9 +57,9 @@
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\[
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\begin{aligned}
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linear &= (1-t) + t \\
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square &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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cubic &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\textit{linear} &= (1-t) + t \\
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\textit{square} &= (1-t)^2 + 2 \cdot (1-t) \cdot t + t^2 \\
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\textit{cubic} &= (1-t)^3 + 3 \cdot (1-t)^2 \cdot t + 3 \cdot (1-t) \cdot t^2 + t^3
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\end{aligned}
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\]
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@@ -67,10 +67,10 @@
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\[
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\begin{aligned}
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linear &= \hspace{2.5em} 1 + 1 \\
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square &= \hspace{1.7em} 1 + 2 + 1\\
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cubic &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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quartic &= 1 + 4 + 6 + 4 + 1
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\textit{linear} &= \hspace{2.5em} 1 + 1 \\
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\textit{square} &= \hspace{1.7em} 1 + 2 + 1\\
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\textit{cubic} &= \hspace{0.85em} 1 + 3 + 3 + 1\\
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\textit{quartic} &= 1 + 4 + 6 + 4 + 1
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\end{aligned}
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\]
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@@ -80,19 +80,19 @@
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\[
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\begin{aligned}
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linear &= BLUE[a] + RED[b] \\
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square &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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cubic &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\textit{linear} &= BLUE[a] + RED[b] \\
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\textit{square} &= BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot RED[b] + RED[b] \cdot RED[b] \\
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\textit{cubic} &= BLUE[a] \cdot BLUE[a] \cdot BLUE[a] + BLUE[a] \cdot BLUE[a] \cdot RED[b] + BLUE[a] \cdot RED[b] \cdot RED[b] + RED[b] \cdot RED[b] \cdot RED[b]\\
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\end{aligned}
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\]
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基本上它就是“每个<i>a</i>和<i>b</i>结合项”的和,在每个加号后面逐步的将<i>a</i>换成<i>b</i>。因此这也很简单。现在你已经知道了二次多项式,为了叙述的完整性,我将给出一般方程:
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\[
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Bézier(n,t) = \sum_{i=0}^{n}
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\underset{binomial~term}{\underbrace{\binom{n}{i}}}
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\textit{Bézier}(n,t) = \sum_{i=0}^{n}
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\underset{\textit{binomial term}}{\underbrace{\binom{n}{i}}}
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\cdot\
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\underset{polynomial~term}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\underset{\textit{polynomial term}}{\underbrace{(1-t)^{n-i} \cdot t^{i}}}
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\]
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这就是贝塞尔曲线完整的描述。在这个函数中的Σ表示了这是一系列的加法(用Σ下面的变量,从...=<值>开始,直到Σ上面的数字结束)。
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