To create 3d data values for drawing ground have to calculate from center (0f, 0f, 0f). The left picture shows the four parts which are divided by center.
Every x and y values are increased and decreased by 1.0 or -1.0 except z values. The increase and decrease values have a same pattern. According many OpenGL examples from Internet, we can draw rectangle with 4 vertex points. Each vertex point has x, y and z value. Therefore, the program has to generate rectangle points’ value. Of course, the generated file has also color values.
int main(int argc, char **argv)
{
int nwidth = atoi(argv[1]);
int nheight = atoi(argv[2]);
fnCVertextFile(nheight, nwidth);
}
Example) program 8 8
When the program was executed like an example, then the vector values will be generated 16 * 16 sizes.
typedef struct {
float x, y, z;
} M3DPoint;
typedef struct {
M3DPoint left, top, right, bottom;
} M3DRect;
// the function writes structure values and string values to file.
void fprintfex(FILE *fvfile, M3DRect row1, char *value)
{
fprintf(fvfile, "%f %f %f %s\n", row1.left.x, row1.left.y, row1.left.z, value);
fprintf(fvfile, "%f %f %f %s\n", row1.top.x, row1.top.y, row1.top.z, value);
fprintf(fvfile, "%f %f %f %s\n", row1.right.x, row1.right.y, row1.right.z, value);
fprintf(fvfile, "%f %f %f %s\n", row1.bottom.x, row1.bottom.y, row1.bottom.z, value);
}
void fnCVertextFile(int aRow, int aColumn)
{
M3DRect row1;
float nleft = 0.0f;
float ntop = 0.0f;
char value1[] = {"0.3 0.3 0.3"};
char value2[] = {"0.5 0.5 0.5"};
char *value;
bool toggle = false;
FILE *fvfile = fopen("vector.dat", "w");
if(fvfile == NULL) {
printf("file cannot open!\n");
exit(-1);
}
// count of vertex
fprintf(fvfile, "%d\n", aRow * aColumn * 4 * 4);
for(int j = 0; j < aRow; j++)
{
for(int i = 0; i < aColumn; i++)
{
row1.left.x = nleft; row1.left.y = ntop; row1.left.z = 1.5f;
row1.top.x = nleft+1.0f; row1.top.y = ntop; row1.top.z = 1.5f;
row1.right.x = nleft+1.0f; row1.right.y = ntop+1.0f; row1.right.z = 1.5f;
row1.bottom.x = nleft; row1.bottom.y = ntop+1.0f; row1.bottom.z = 1.5f;
value = (toggle) ? value1 : value2;
fprintfex(fvfile, row1, value);
toggle = !toggle;
nleft += 1.0f;
}
ntop += 1.0f;
nleft = 0.0f;
toggle = !toggle;
}
// was ommited below section of source
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