Converting simple code from basic to c...

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Socoder -> C/C++/C#/Other -> Converting simple code from basic to c...
Fri, 05 Oct 2007, 04:01
spinal	I having trouble converting this code to c. ; Mouse string, spinal Graphics 640,480,0,2 Global tail_len = 20 ; pixel length between the nodes (10 * what we need) Global tail_nodes = 50 ; How many sections the tail is Dim nodes_x(tail_nodes) ; X position of each node Dim nodes_y(tail_nodes) ; Y position For x=1 To tail_nodes nodes_x(x) = MouseX()10 nodes_y(x) = MouseY()10 Next HidePointer SetBuffer BackBuffer() Repeat Cls move_tail() Flip 1 Until KeyHit(1) End Function move_tail() nodes_x(0) = MouseX()10 nodes_y(0) = MouseY()10 For x=1 To tail_nodes rotation = ATan2(nodes_y(x)-nodes_y(x-1),nodes_x(x)-nodes_x(x-1)) pos_x = nodes_x(x-1) + tail_len * Cos(rotation) pos_y = nodes_y(x-1) + tail_len * Sin(rotation) nodes_x(x) = pos_x nodes_y(x) = pos_y x1 = nodes_x(x-1)/10 y1 = nodes_y(x-1)/10 x2 = nodes_x(x)/10 y2 = nodes_y(x)/10 Color 255,255,255 Line x1,y1,x2,y2 Next End Function --v I have the following, but the tail floats towards the top left, rather than following the mouse. The code is for the DS, but the maths sould be understandable by most people. // Includes #include <PA9.h> // Include for PA_Lib #include <math.h> // needed for the maths // some variables for the tail const u8 tail_len = 5; // length of segment const u8 tail_nodes = 50; // numer of segments u8 nodes_x[100]; u8 nodes_y[100]; void move_tail(void); // Function: main() int main(int argc, char ** argv) { PA_Init(); // Initializes PA_Lib PA_InitVBL(); // Initializes a standard VBL // set color1 on screen0 to white PA_SetBgPalCol(0, 1, PA_RGB(31, 31, 31)); // set bitmap for both screens PA_Init8bitBg(0, 3); PA_Init8bitBg(1, 3); // Infinite loop to keep the program running while (1) { PA_Clear8bitBg(0); // clear the screen move_tail(); PA_WaitForVBL(); } return 0; } // End of main() // call this each frame to move the string void move_tail(void) { nodes_x[0]=Stylus.X; nodes_y[0]=Stylus.Y; int temp; for(temp=1; temp<tail_nodes; temp++) { float rotation = atan2(nodes_y[temp]-nodes_y[temp-1] , nodes_x[temp]-nodes_x[temp-1]); nodes_x[temp] = nodes_x[temp-1] + tail_len * cos(rotation); nodes_y[temp] = nodes_y[temp-1] + tail_len * sin(rotation); int x1 = nodes_x[temp-1]; int y1 = nodes_y[temp-1]; int x2 = nodes_x[temp]; int y2 = nodes_y[temp]; PA_Draw8bitLine(0,x1,y1,x2,y2,1); } } --v If anyone can tell me why the tail floats towards top left, I need this fixed. It's bugging me a bit. -=-=- Check out my excellent homepage!
Fri, 05 Oct 2007, 05:06
mike_g	Just a random guess without looking at the code much, but you might need to convert from radians to degrees?
Fri, 05 Oct 2007, 14:18
spinal	I don't think thats it, the angles seem only slightly out, I would expect if that were the case, the agnles would seem almost random. -=-=- Check out my excellent homepage!
Fri, 05 Oct 2007, 14:23
Phoenix	Maybe it's not required (I haven't tried the code), but it seems like you forgot to translate this part of the code: For x=1 To tail_nodes nodes_x(x) = MouseX()10 nodes_y(x) = MouseY()10 Next --v
Fri, 05 Oct 2007, 15:09
spinal	nope, thats just for setting the start points, it doesn't make any difference once the mouse/stylus is squiggling about the screen. It seems the angle is being calculated wrong. -=-=- Check out my excellent homepage!
Fri, 05 Oct 2007, 17:07
spinal	I managed to get it to work in the same way as the blitz version, it was most likely not calculating the angle correctly due to the closeness of each of the sets of points. I multiplied everything by 10 then divided it when plotting. I kept forgetting my nodes were u8, I changed it to u16 and it seems fine now. Thanks for the help guys. Here is the code in case I loose it in the future ( I have a habit of doing that!). // Includes #include <PA9.h> // Include for PA_Lib #include <math.h> // needed for the maths // some variables for the tail int tail_len = 20; // length of segment int tail_nodes = 50; // numer of segments u16 nodes_x[100]; u16 nodes_y[100]; void move_tail(void); // Function: main() int main(int argc, char ** argv) { PA_Init(); // Initializes PA_Lib PA_InitVBL(); // Initializes a standard VBL // set color1 on screen0 to white PA_SetBgPalCol(0, 1, PA_RGB(31, 31, 31)); // set bitmap for both screens PA_Init8bitBg(0, 3); PA_Init8bitBg(1, 3); // Infinite loop to keep the program running while (1) { PA_WaitForVBL(); PA_Clear8bitBg(0); move_tail(); } return 0; } // End of main() // call this each frame to move the string void move_tail(void) { nodes_x[0]=Stylus.X10; nodes_y[0]=Stylus.Y10; int i,x1,y1,x2,y2; float rotation; for(i=1; i<tail_nodes; i++) { float nx=nodes_x[i-1]; float nx1=nodes_x[i]; float ny=nodes_y[i-1]; float ny1=nodes_y[i]; rotation = atan2(ny1-ny , nx1-nx); nodes_x[i] = nx + tail_len * cos(rotation); nodes_y[i] = ny + tail_len * sin(rotation); x1 = nodes_x[i-1]/10; y1 = nodes_y[i-1]/10; x2 = nodes_x[i]/10; y2 = nodes_y[i]/10; PA_Draw8bitLine(0,x1,y1,x2,y2,1); } } --v \|edit\| I have increased the accuracy enough by multiplying by 100 also by using sprites, I can use a tiles background instead of a bitmap one. This might just make a nice game. -=-=- Check out my excellent homepage!