test_marcher.c

#include "marcher.h"
#include "unittest.h"

/****************************** Weight Functions *****************************/

// Weight function (1)
//  The weight between two pixels is the euclidean distance between
//  the (R,G,B) values of the 2 pixels. (If we think of them as vectors)
double similarColour(Image *im, int a, int b)
{
  Pixel col1 = getPixel(im, a), col2 = getPixel(im, b);
  double a1 = (col1.R - col2.R);
  double b1 = (col1.G - col2.G);
  double c1 = (col1.B - col2.B);
  double sumSq = (a1 * a1) + (b1 * b1) + (c1 * c1);
  return sqrt(sumSq) + 0.01;
}

// Weight function (2)
//   The weight between two pixels is simply how close the 2nd pixel is
//   from the colour white (255, 255, 255).
double howWhite(Image *im, int a, int b)
{
  // Don't even use the current pixel's colur here... the weight
  // functions are arbitrary :)
  Pixel col2 = getPixel(im, b);
  double a1 = (255 - col2.R);
  double b1 = (255 - col2.G);
  double c1 = (255 - col2.B);
  double sumSq = (a1 * a1) + (b1 * b1) + (c1 * c1);
  return sqrt(sumSq / 100.0) + 0.01;
}

/*****************************************************************************/

void run_test(char *filename, WeightFunc wf, double expectedCost)
{
  Image *img = readPPMimage(filename);
  int *path = calloc(sizeof(int), img->sx * img->sy);
  double cost = findPath(img, wf, path);
  outputPath(path, img);
  if (fabs(cost - expectedCost) >= 10e-4)
    TEST_FAIL("Cost (%f) did not match expected answer (%f).\n",
              cost, expectedCost);
  free(path);
  freeImage(img);
}

TEST(water) { run_test("images/water.ppm", similarColour, 1280.81526); }
TEST(spiral) { run_test("images/spiral.ppm", similarColour, 991.255407); }
TEST(maze) { run_test("images/maze.ppm", howWhite, 12.400000); }
TEST(bigmaze) { run_test("images/bigmaze.ppm", howWhite, 8.620000); }
TEST(grad) { run_test("images/grad.ppm", similarColour, 278.751493); }

TEST(all_colour_weight)
{
  Image *img = readPPMimage("images/25colours.ppm");
  int *path = calloc(sizeof(int), img->sx * img->sy);
  double cost = findPath(img, allColourWeight, path);
  printf("(Outputting image: inspect this manually) ");
  outputPath(path, img);
  free(path);
  freeImage(img);
}

int main(int argc, char *argv[])
{
  unit_main(argc, argv);

  printf("\n"
         " - You have passed the test cases, your solution is on the right track.\n"
         " - It is left up to you to verify that your path itself is correct, and\n"
         " - that allColourWeight() works as intended...\n");

  return 0;
}