How can i convert pixel to [-1..1]coordinate in opengl? Which function? I want to write a program that is work with
glutmousefunc(),
When I click on the screen a ball is appear on it where clicked. but mouse work with pixel and circle work with coordinate between -1 and 1 ....
I have a linear buffer coordinate, i am to print onto a screen coordinate.
Say maxy = 20, maxx = 10, bufferx = 20, y, x,
Buffer coordinates to screen coordinates:
Algorithm: So for each maxx'th of bufferx, y will +1 and x will reset.
Mathematical: y = int bufferx / maxx,
const double averageIncr = int (maxx+1/maxx) - double (maxx+1/maxx);
So the amount of averageIncr in (int bufferx / maxx - float bufferx / maxx)
is the screen x coordinate. Then
(int bufferx / maxx - float bufferx / maxx) / averageIncr = x
Screen coordinates to buffer coordinates:
bufferx, y = 21, x = 10, maxy = 20, maxx = 10,
y * x would be the case if bufferx <= max screen coordinate.
There is no max bufferx.
How to find the transition from screen coordinates to buffer coordinates? Also, if the algorithm within a for loop, or that the mathematical way would be slower or not? I rarely touch floating point stuff.
I have a character at a co-ordinate, say (3,4) for example, and I need to get him to (10,15). I would like him to move one block every tick or half a second, so that you can see him moving towards his destination. How to achieve this?
View 3 Replies View RelatedSo, in a program I'm making, I have an idea, that I can print the character background first, then print another layer on top of the background. Can I do that? But I need to be able to place a single character at a certain position, what function does that?
View 5 Replies View RelatedAfter searching on stackoverflow I got this
POINT p;
for (int i = 0;; ++i) {
HWND hwnd = GetConsoleWindow();
system("cls");
if (ScreenToClient(hwnd, &p)) {
//p.x and p.y are now relative to hwnd's client area
} cout << p.x << " " << p.y;
Sleep(200);
}
I'm looking for a function that gives current mouse position(x and y) in that particular console window. I've tried above code but it is not working.
I have 2 points in a cartesian coordinate system, where the first point is always (0,0). Given the second point and a heading in degrees, how would I write an algorithm to determine if the 2nd point is traveling in the general direction of (0,0) ?
For example:
Point a (0,0)
Point b (10,0)
Point b heading = 270 degrees
This would be true this 270 degrees points right and point b is 10 units right of point a. I would probably also want this is be fuzzy somewhat, in that anything from say + or - 30 degrees would also be true, or something like this.
Cam is a pointer to a structure and viewpoint is a vector located within the struct. I am trying to read in from a file the coordinates for the vector. I have also tried &cam->view_point->x as well as &cam.view_point.x and it tells me that I am requesting something not in a struct
Code: count= fscanf(in,"%d %d %d", &cam->view_point.x, &cam->view_point.y,&cam->view_point.z);
How to read pixels from an x,y coordinate using the VGA register values?
byte readVRAMdirect(VGA_Type *VGA, uint_32 start, uint_32 offset) //Used in 256 color mode!
{
if (!VGA->VRAM_size) return 0; //No size!
return VGA->VRAM[SAFEMOD((start*4)+offset,VGA->VRAM_size)]; //The full protected offset!
[code]....
getVRAMScanlineStart(VGA,y) gives the offset register multiplied by 2 (shl 1), multiplied with the current memory address size (byte, word or dword) multiplied by the scanline. 256-color mode is already working. GETBIT gives a bit #(0-7) of a specified byte.
writeVRAMplane & readVRAMplane are used by the CPU to write data to VRAM (address 0xA000:xxxx-0xBFFF:xxxx), determined by the memory read and write modes(working) and the odd/even, planar or chain4 enable mode (working).how to get the 16 color and interleaved shift mode working?
ZIP with screen captures: URL....
I am drawing in a simple (square) MFC window. I realize that (0,0) starts in the upper left hand corner. I wanted to see how MFC handled drawing of angles, so I use this code:
Code:
double CompassDegreesToRadians(double compassDegrees) {
return((PI / 2.0f) - (compassDegrees * PI / 180.0f));
}
// Make pen
CPen penRed;
penRed.CreatePen(PS_SOLID | PS_COSMETIC, 1, RGB(255, 0, 0));
// Test Angles
[Code] .....
Using this code, and changing the value of angle1 to these values (0, 90, 180, 270) I think MFC uses the coordinate system:
Code:
180 -y
|
|
-x 270---------------- 90 +x
|
|
0 +y
This seems like a strange coordinate system to use. Am I doing something wrong? If this is correct, how can I convert my calculations to this coordinate system? (compass degrees):
Code:
0 +y
|
|
-x 270---------------- 90 +x
|
|
180 -y
I am very much new to C programming. However, I have an assignment regarding linked list.
Problem Statement is: Using linked list store the coordinates of four cartesian points and then find the coordinates having longest distance from its origin.
I am working on image processing in C + + and opencv, I treat images in grayscale, ie the pixel values it must be between 0 (black) to 255 (white).
Mat img; img = imread (file, -1);
for ( int i = 0; i < img. rows ; i ++) {
for ( int j = 0; j < img. cols ; j ++) {
val_pixel=img.at < double >(i,j);
printf( "%d ",val_pixel);
}
printf( "
");
}
when displaying the pixel value from two loop, I get values to 0 and it is normal for propablement black areas, but for whites I find the value -2147483648. I don't understand why this value is not 255.Is there an explanation for this has value.
I use SDL2. and i was testing some functions i took from some internet and some unwanted results happened.
Code :
Pixel *GetPixel(SDL_Surface *surface, int x, int y) {
Uint8 p8, *buf8;
Uint16 p16, *buf16;
Uint32 p32, *buf32;
switch(surface->format->BitsPerPixel {
[Code] .....
And the output changes time to time.
I have an image of size 640x480 pixels. It's possible to obtain the dimension in mm of one pixel from that image given only that size?I do not have the size of the image in mm,however.
View 5 Replies View RelatedHow can I find each and every pixel in a circle so that I can do some operations on it.
View 6 Replies View RelatedHow can I import a font file and get the pixel information of the letters so I can make my own custom text drawing function?
I basically have a pixel surface (a 2D array) and I want to draw the text to that array.
I wrote a script that generates n random pixel positions and draws them to the screen. Works well. Now i tried to rotate them. Rotating does work too. But it does not work as i planned it.
paramters 'angle' and 'timestep' work somehow, but not as they should do. the function 'move' is supposed to rotate the pixelfield 'angle' degrees in a given direction, addicted to the 'timestep' parameter. 'timestep' is needed time for drawing in one single game loop.
angle_step = timestep * angle
// x
ppdPoint[i]->x =
pRotationPoint->x + cos(angel_step) * (ppdPoint[i]->x - pRotationPoint->x) - sin(angel_step) * (ppdPoint[i]->y - pRotationPoint->y);
// y
ppdPoint[i]->y =
pRotationPoint->y + sin(angel_step) * (ppdPoint[i]->x - pRotationPoint->x) + cos(angel_step) * (ppdPoint[i]->y - pRotationPoint->y);
rotation point is the middle of the screen. when i set angle to 10 it should rotate 10 degrees / second. Instead it's rotating very very fast and all stars are moving nearer to the center of the screen, so after x rounds there is just 1 pixel left in the middle of the screen. there is a kind of gravition.I'm working with SDL2. What I did find out:
FPS is <= 60, 'cause of the 'SDL_RENDERER_PRESENTVSYNC' flag. When i skip that flag, for any reason the 'gravition' would take more time. FPS is <= 1400 then, 'though i got a natural game loop (i hope):
while(pBuild->getExecuteFlag())
{
pBuild->draw();
pBuild->update(time_dif, pTimeWindow->TimeStampB);
time_dif = (pTimeWindow->TimeStampB - pTimeWindow->TimeStampA);
time_dif *= 0.001;
pTimeWindow->TimeStampA = pTimeWindow->TimeStampB;
pTimeWindow->TimeStampB = SDL_GetTicks();
pBuild->count_fps(pTimeWindow->TimeStampB);
}
So maybe (timestep * angle) isn't the right way?
Im new to c#. In c++ I have made a window and painted it with dots and concentric circles, like a radar PPI screen. Trying to do this in c#, I can't find how to draw a single pixel on the window.
Also, what should I be drawing on: the form, panel, picturebox...?
I would like to subtract one image from another to get something like "differential picture" (i am not sure whether the name is correct). I've managed to read the FILEHEADER and FILEINFOHEADER of bitmap. I will subtract 24-bit bmp files only. However i can't understand the structure of this file. So far my code looks like this. Any example of at least copying one bmp file to a new one? This example would be useful, because subtracting will be simillar, instead of copying the pixel value i will just put abs(value1-value2) in the output.
Code:
// ConsoleApplication1.cpp : Defines the entry point for the console application.
#include "stdafx.h"
#include <iostream>
#include <fstream>
using namespace std;
struct BITMAPfileHEADER {
[Code] .....
I have the code and it compiles fine but it doesn't work. (i am using the coding made easy sfml 2.0 tutorials)
Code:
#include <SFML/Graphics.hpp>
#include <iostream>
#include <algorithm>
#include <vector>
class Player {
public:
sf::Sprite player;
[Code] ....
I am using the SDL library, and came across a way to access pixel data.
//A pointer to a surface structure
SDL_Surface *w = SDL_SetVideoMode(800,400,8,SDL_SWSURFACE);
//Casting a void pointer pointing to an array of memory locations(the pixels), to a pointer to an array of Uint8's.
//SDL_MapRGB() Returns an Uint32 containing the color 0,0,255,(0/255, i think it returns the transparency too, or else it would rather return a Uint24,not sure).
Then modifying the memory location, in this case the pixel at the middle of the window.
static_cast<Uint8*>(w->pixels)[(200*w->pitch)+400]=SDL_MapRGB(w->format,0,0,255);
What i seem to not understand is that, i cast pixels to Uint8*, which means I now have a pointer to an array of 8bit numbers, but SDL_MapRGB seemingly returns an Uint32 or Uint24 for a color composed of r,g,b, together without 'a' is 24bits(256=1b,256=1b,256=1b)=3b.
And then i somehow assign that pixel which is of 8bit at chosen location, an Uint24 or 32bit unsigned int.
How does this work?
I'm currently working with linear VRAM (a buffer with 256KB memory, divided into four 64k planes, so plane 0 at 0x00000, plane 1 at 0x10000, plane 2 at 0x20000, plane 3 at 0x30000). Just add the index of the plane to that for the full address in VRAM.
I'm still wondering how to get a specific pixel from VRAM (x,y coordinate) when doing graphic modes (none color modes work, only the black/white pixels (1-bit) graphic mode works).
how I can get specific pixels from the VGA VRAM (having linear access described above) using Shift Register Interleave mode (VGA modes 4&5), 16-bit planar mode (Most VGA modes) etc.
I have tried everything and i still can't access pixel RGB values in float format.
I tried vec3b which produces strange characters which i can't covert to float as it says no suitable function exists.
I tried vector<float> RGB;
with RGB = image.at<vector<float>>(row,col);
I get a unhandled exception error.
So whatever i do, if it is syntax correct i get unhandled exception error. If it should work i get this stupid error. I need it for chroma keying.
I have a bw(grayscale) image and want to calculate the slope for each pixel which returns a value 0 to 255 value.
Pixels are always between 0 and 255. The highest possible difference is 255. The end result would be 0 for no slope and 256 for the highest slope.
Would this formula work?
slopex = pixel[x+1,y] - pixel[x - 1,y];
slopey = pixel[x,y+1] - pixel[x,y - 1];
totalslope = sqrt(slopex * slopex + slopey * slopey)*256;
I have managed to successfully extracted the BMP file header and file info but ran into troubles with getting the pixel data out into a 2d array.This is my function to read the data while i have another to write the data. The output does not match the input at all.
void BMPProgram::GetPixelData(std::ifstream & inStream) {
std::cout << "Entered function";
if(inStream.fail())
return;
//space allocated to reading in of padding
int paddingSpace = 0;
[Code] ....
PIXEL is a struct of 3 unsigned char containing values of RGB.
I'm trying to read a jpeg pixel and then compare it if it'x bigger than a number to change it. Either I'm breaking the folder if I start less than 22000 which is very large number shouldn't include the header or I'm getting solid color without any different.
Code:
const char* filename ="Hydrangeas.JPG";
const char* nfilename ="Hydrangeas1.JPG";
FILE *ptr_old, *ptr_new;
errno_t err = 0, err1 = 0;
int a;
[Code] ....
In this project I need to develop few functions to work with graphics card. I work in minix and this is pretty rubbish.
I'm having an hard time to read a pixel map, or atleast to print it on my main function.
I have a read_xpm function, which is given, therefore, working.
Code:
char *read_xpm(char *map[], int *wd, int *ht)
Then I have a pixmap.h file which gives some examples of pixmap images that I can use as example:
Code:
static char *pic1[] = {
"32 13 4",
". 0",
"x 2",
"o 14",
"+ 4",
[Code] ....
The doubt is. I have a test_xpm function and I need to call this char array but this is so many pointers that I can't even figure out where I'm pointed to (?)
Code: int test_xpm(unsigned short xi, unsigned short yi, char *xpm[])
I tried something like read_xpm(xi, yi, *xpm[0]); but I'm guessing I need to index that array and run all those chars in order to show them.
