OpenGL Flare Design

One

When writing the wind-blown banner effect, note that the previous point and the next point, such as the z-coordinate relationship, the next point of the z-coordinate is the z-coordinate of the previous point, in fact, by the transfer of the wave to calculate, z-coordinate can be any curve of the function to calculate, such as sin, cos, this is just the , it depends on the algorithm, but the dynamic implementation is the coordinate transfer.

If the flag is divided into 44 rows, 44 columns, only the z-coordinate transfer, not the test x and Y,

So, a total of 45 * 45 points, each point three coordinate values

const float PI = 3.1415;

const int row = 44; //number of rows to be divided

const int column = 44; //number of columns to be divided

Const FLOAT length = 9; //The length of the banner

Const DISX = length/(float) column;

Const DISY = length/(float) row;

float coord[row][column][3];

//row-by-row calculation of coordinate values

for (int i=0; i < row; i++) {

Float y = i * disy-length/2.0;

for (int j=0; j < column; J + +) {

Coord[i][j][0] = j * disx-length/2.0; //To ensure that the banner is in the middle

Coord[i][j][1] = y;

Coord[i][j][2] = sin ((float) j/(FLOAT) colum * 2.0 * PI);

Note that the two numbers are integers when you divide.

}

}

Passing Z-coordinates

for (int i=0; i < row; i++) {

float hold = coord[i][0][2]; //Save the z-coordinate of the first point, and the last point to use

for (int j=0; J < Column-1; J + +) {

coord[i][j][2] = coord[i][j+1][2];

}

COORD[I][COLUMN-1] = hold;

}

This is the simplest calculation, the z coordinate of each column is the same, repeat the z coordinate of the last point and the first point z coordinate, you can also calculate the z coordinate of the column point according to a certain curve equation, then pass it to the next point, and the x and Z coordinates may also change, here is the simplest form.

Two

To enable the z-axis to move vertically and to move horizontally, two arrays are required to hold the z-coordinate values in both horizontal and vertical directions. Then the z coordinate is the composition of these two coordinate values:

const int row = 45;

const int column = 45;

const float Width= 9.0f;

Const float height = 9.0f;

float coord[row][column][3]; //Flag coordinates

float Hzcoord[row][column]; //flag z-coordinate horizontal component

float Vzcoord[column][row]; //Flag z-coordinate vertical component

//Calculate the horizontal component of the z-coordinate

for (int i = 0; i < row; i++) {

for (int j = 0; j < column; J + +) {

Hzcoord[i][j] = sin ((float) j/(float) column * 360 * 3.1415/180);

}

}

//Calculate the vertical component of the z-coordinate

for (int i = 0; i < column; i++) {

for (int j = 0; J < Row; J + +) {

Vzcoord[i][j] = sin ((float) j/(float) column * 360 * 3.1415/180);

}

}

float disx = width/column;

float Disy = Height/row;

//calculate coordinates for each point

for (int i = 0; i < row; i++) {

for (int j = 0; j < column; J + +) {

COORD[I][J][0] = J * disx-width/2.0;

COORD[I][J][1] = i * disy-height/2.0;

COORD[I][J][2] = Hzcoord[i][j] + vzoord[j][i];

}

}

The coordinates of each point are initialized, and the z-coordinate is passed at each frame of the dynamic:

//The transfer of horizontal coordinate components

for (int i = 0; i < row; i++) {

Float hold = hzcoord[i][0];

for (int j = 0; J < Column-1; J + +) {

HZCOORD[I][J] = hzcoord[i][j+1];

}

HZCOORD[I][COLUMN-1] = hold;

}

Transfer of//vertical coordinate components

for (int i = 0; i < column; i++) {

Float hold = vzcoord[i][0];

for (int j = 0; J < Row-1; J + +) {

VZCOORD[I][J] = vzcoord[i][j+1];

}

VZCOORD[I][ROW-1] = hold;

}

//coordinates of each point to be computed at each frame

for (int i = 0; i < row; i++) {

for (int j = 0; j < column; J + +) {

//x and Y coordinates we don't have to change, because only the z-coordinate changes are considered.

COORD[I][J][0] = J * disx-width/2.0;

COORD[I][J][1] = i * disy-height/2.0;

COORD[I][J][2] = Hzcoord[i][j] + vzoord[j][i];

}

}

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OpenGL Flare Design