三维立体算法:
- /*
- * 3DCaptcha for .net
- *
- * http://www-personal.umich.edu/~mressl/3dcaptcha/ (php)
- * http://code.google.com/p/3dcaptcha/ (php)
- *
- * Translate : Aimeast
- * Blog : http://www.cnblogs.com/Aimeast/
- */
-
- using System;
- using System.Drawing;
-
- namespace Captcha
- {
- public static class Captcha
- {
- private static double[] addVector(double[] a, double[] b)
- {
- return new double[] { a[0] + b[0], a[1] + b[1], a[2] + b[2] };
- }
-
- private static double[] scalarProduct(double[] vector, double scalar)
- {
- return new double[] { vector[0] * scalar, vector[1] * scalar, vector[2] * scalar };
- }
-
- private static double dotProduct(double[] a, double[] b)
- {
- return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
- }
-
- private static double norm(double[] vector)
- {
- return Math.Sqrt(dotProduct(vector, vector));
- }
-
- private static double[] normalize(double[] vector)
- {
- return scalarProduct(vector, 1.0 / norm(vector));
- }
-
- // http://en.wikipedia.org/wiki/Cross_product
- private static double[] crossProduct(double[] a, double[] b)
- {
- return new double[] {
- (a[1] * b[2] - a[2] * b[1]),
- (a[2] * b[0] - a[0] * b[2]),
- (a[0] * b[1] - a[1] * b[0])
- };
- }
-
- private static double[] vectorProductIndexed(double[] v, double[] m, int i)
- {
- return new double[]{
- v[i + 0] * m[0] + v[i + 1] * m[4] + v[i + 2] * m[8] + v[i + 3] * m[12],
- v[i + 0] * m[1] + v[i + 1] * m[5] + v[i + 2] * m[9] + v[i + 3] * m[13],
- v[i + 0] * m[2] + v[i + 1] * m[6] + v[i + 2] * m[10]+ v[i + 3] * m[14],
- v[i + 0] * m[3] + v[i + 1] * m[7] + v[i + 2] * m[11]+ v[i + 3] * m[15]
- };
- }
-
- private static double[] vectorProduct(double[] v, double[] m)
- {
- return vectorProductIndexed(v, m, 0);
- }
-
- private static double[] matrixProduct(double[] a, double[] b)
- {
- double[] o1 = vectorProductIndexed(a, b, 0);
- double[] o2 = vectorProductIndexed(a, b, 4);
- double[] o3 = vectorProductIndexed(a, b, 8);
- double[] o4 = vectorProductIndexed(a, b, 12);
-
- return new double[]{
- o1[0], o1[1], o1[2], o1[3],
- o2[0], o2[1], o2[2], o2[3],
- o3[0], o3[1], o3[2], o3[3],
- o4[0], o4[1], o4[2], o4[3]
- };
- }
-
- // http://graphics.idav.ucdavis.edu/education/GraphicsNotes/Camera-Transform/Camera-Transform.html
- private static double[] cameraTransform(double[] C, double[] A)
- {
- double[] w = normalize(addVector(C, scalarProduct(A, -1)));
- double[] y = new double[] { 0, 1, 0 };
- double[] u = normalize(crossProduct(y, w));
- double[] v = crossProduct(w, u);
- double[] t = scalarProduct(C, -1);
-
- return new double[]{
- u[0], v[0], w[0], 0,
- u[1], v[1], w[1], 0,
- u[2], v[2], w[2], 0,
- dotProduct(u, t), dotProduct(v, t), dotProduct(w, t), 1
- };
- }
-
- // http://graphics.idav.ucdavis.edu/education/GraphicsNotes/Viewing-Transformation/Viewing-Transformation.html
- private static double[] viewingTransform(double fov, double n, double f)
- {
- fov *= (Math.PI / 180);
- double cot = 1.0 / Math.Tan(fov / 2);
-
- return new double[]{
- cot, 0, 0, 0,
- 0, cot, 0, 0,
- 0, 0, (f + n) / (f - n), -1,
- 0, 0, 2 * f * n / (f - n), 0
- };
- }
-
- public static Image Generate(string captchaText)
- {
- Random rnd = new Random();
-
- // 3dcha parameters
- int fontsize = 24;
- Font font = new Font("Arial", fontsize);
-
- SizeF sizeF;
- using (Graphics g = Graphics.FromImage(new Bitmap(1, 1)))
- {
- sizeF = g.MeasureString(captchaText, font, 0, StringFormat.GenericDefault);
- }
-
- int image2d_x = (int)sizeF.Width;
- int image2d_y = (int)(fontsize * 1.3);
-
- double bevel = 4;
-
- // Create 2d image
- Bitmap image2d = new Bitmap(image2d_x, image2d_y);
- Color black = Color.Black;
- Color white = Color.White;
-
- // Paint 2d image
- using (Graphics g = Graphics.FromImage(image2d))
- {
- g.Clear(black);
- g.DrawString(captchaText, font, Brushes.White, 0, 0);
- }
- // Calculate projection matrix
- double[] T = cameraTransform(
- new double[] { rnd.Next(-90, 90), -200, rnd.Next(150, 250) },
- new double[] { 0, 0, 0 }
- );
- T = matrixProduct(
- T,
- viewingTransform(60, 300, 3000)
- );
-
- // Calculate coordinates
- double[][] coord = new double[image2d_x * image2d_y][];
-
- int count = 0;
- for (int y = 0; y < image2d_y; y += 2)
- {
- for (int x = 0; x < image2d_x; x++)
- {
- // calculate x1, y1, x2, y2
- int xc = x - image2d_x / 2;
- int zc = y - image2d_y / 2;
- double yc = -(double)(image2d.GetPixel(x, y).ToArgb() & 0xff) / 256 * bevel;
- double[] xyz = new double[] { xc, yc, zc, 1 };
- xyz = vectorProduct(xyz, T);
-
- coord[count] = xyz;
- count++;
- }
- }
-
- // Create 3d image
- int image3d_x = 256;
- //$image3d_y = $image3d_x / 1.618;
- int image3d_y = image3d_x * 9 / 16;
- Bitmap image3d = new Bitmap(image3d_x, image3d_y);
- Color fgcolor = Color.White;
- Color bgcolor = Color.Black;
- using (Graphics g = Graphics.FromImage(image3d))
- {
- g.Clear(bgcolor);
- count = 0;
- double scale = 1.75 - (double)image2d_x / 400;
- for (int y = 0; y < image2d_y; y += 2)
- {
- for (int x = 0; x < image2d_x; x++)
- {
- if (x > 0)
- {
- double x0 = coord[count - 1][0] * scale + image3d_x / 2;
- double y0 = coord[count - 1][1] * scale + image3d_y / 2;
- double x1 = coord[count][0] * scale + image3d_x / 2;
- double y1 = coord[count][1] * scale + image3d_y / 2;
- g.DrawLine(new Pen(fgcolor), (float)x0, (float)y0, (float)x1, (float)y1);
- }
- count++;
- }
- }
- }
- return image3d;
- }
- }
- }
复制代码 使用方法:
- this.BackgroundImage = Captcha.Generate("Code");
复制代码
效果图:
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