Thread: Triangle and Line Segment Intersection

Since you're only creating one cube, we don't need [1]. We can do the following:

Code:

cube myCube;

myCube.v0.x = 0;
myCube.v7.y = 0;
/* And so on. */

Or...

Code:

scanf("%f", &myCube.v0.x);

You've got it!

Yikes, sorry... one more question...

earlier you used a loop to input (with k as loop variable):

within this, I need something to the effect of "&myCube.v[k].x" rather than "&myCube.v0.x"

It doesnt seem my current structure will allow this.

What about this:

Code:

typedef struct
{
	double x;
	double y;
	double z;
} point;

typedef struct
{
	point p1;
	point p2;
	point p3;
} triangle;

typedef struct
{
	point p1;
	point p2;
} segment;

typedef struct
{
	point v0;
	point v1;
	point v2;	
	point v3;
	point v4;
	point v5;
	point v6;
	point v7;
} cube;

int DoesIntersect(triangle tri, segment seg);


// main
int main(void)
{
	triangle tri;
	segment seg;
	int result;
	
	int j;
	char input_buffer[160];
	int check_input;
	double u;

	cube input_cube; 

	for ( j = 0; j < 8; j++)
		{
			printf("Input vertex coordinates x y z: ");
			fflush(stdout);
			fgets(input_buffer, sizeof input_buffer, stdin);
			check_input = sscanf(input_buffer, "&#37;f %f %f", &input_cube.[j].x, &input_cube.[j].y, &input_cube.[j].z);

			if (check_input !=3)
			{
				printf("Improper format.");
				return 0;
			}
		}

I understand the dilemma completely.

Unfortunately, we can't have "variable" variable names. v0 must always be v0, v1 must always be v1. So in this sense, if we keep the current structures and the current implementation of our input calls, we need to add a line for each vertex v0, v1, ..., v8.

So you would have one sscanf() for each vertex v0, v1, ..., v8.

We could venture into the land of pointers and attempt to do it that way (by having a pointer to our cube structure and then using our loop variable to somehow increment our pointer through the structure and its sub-structures, or "points"), but we'd quickly be approaching the limits of my capability. I'm sure we could stumble through it (I have a decent idea on how we would do it), but it might be a bit too complex for our purposes.

Back when I said we needed a loop, I was under the impression you were asking the user to input EIGHT triangles.

Now, we're just inputting ONE cube. So we can ditch the loop and simply have 8 sscanf() statements and their accompanying prompts and buffers (similar to what I did for prompting the user for each point in the triangle, except now you're asking the user for each point of the cube). And if you're concerned about keeping your main() relatively clean, once you have the functionality installed, you can go back and modularize further by creating a "UserPrompt" or "UserInput" function.

*** BIG EDIT ***

Oh! Idea!

You could create an array of vertices in your cube data structure like this:

Code:

typedef struct
{
     point vertices[8];
} cube;

Then, you could loop around as before:

Code:

for (j = 0; j < 8; j++)
{
     scanf("&#37;f", &myCube.vertices[j].x, &myCube.vertices[j].y, &myCube.vertices[j].z);
}

I'm feeling pretty dumb for not catching myself on that earlier. Try that!

Of course, cube can be defined as:

Code:

typedef struct
{
	point v[8];
} cube;

--
Mats