Matrices!!

i hope this helps.

http://www.gamedev.net/hosted/3dgraphics/tutorial/index.html

that is a 3d tutorial and it''ll show you how to work with matrices.

i recommend you get a book on it and start learning. a uni math text on it should be fine. you''ll likely have to know calculus, however.

There isn''t much to know about Matrices, atleast not enough to buy a book about it, you can probably write the basics of matrix calculations on 10 pages, heck, on school i have it explained in 4 pages, however i will provide you with a 2 classes coded in JAVA, you can probably rewrite it in another language if you want to.
It is part of a project for school, on which i am working, hope you find it usefull.

the code below is slightly skewed. sorry about that.
-----------------------------------------------------------------
//////////////////////////////////////////////////////////////
// class StackedMatrixHandler //
// helper class to combine and stack multiple matrices //
//////////////////////////////////////////////////////////////
package engine3D;

public class StackedMatrix4DHandler
{
private Matrix4D[] stackedMatrix;
private int currentMatrix;

// baseMatrices for translation, scale and rotation, used for multiplication with other matrices
private Matrix4D translateMatrix;
private Matrix4D scaleMatrix;
private Matrix4D rotateMatrix;

private float[] sinTable;
private float[] cosTable;

public StackedMatrix4DHandler()
{
stackedMatrix = new Matrix4D[32];
clearMatrix4DStack();

translateMatrix = new Matrix4D();
scaleMatrix = new Matrix4D();
rotateMatrix = new Matrix4D();

sinTable = new float[360];
cosTable = new float[360];
for (int i =0; i < 360; i++)
{
sinTable = ((float)Math.sin((Math.PI/180)*i));
cosTable[i] = ((float)Math.cos((Math.PI/180)*i));
}
}

public void pushMatrix4D(Matrix4D matrix) throws MatrixException
{
if (currentMatrix == 31) throw new MatrixException("Matrix stack overloaded");

stackedMatrix[currentMatrix] = (Matrix4D)matrix.clone();
currentMatrix++;
stackedMatrix[currentMatrix] = matrix;
}

public Matrix4D popMatrix4D() throws MatrixException
{
if (currentMatrix == 0) throw new MatrixException("Matrix stack depleted");

stackedMatrix[currentMatrix] = null;
currentMatrix--;

return stackedMatrix[currentMatrix];
}

public Matrix4D getCurrentMatrix4D()
{
if (stackedMatrix[currentMatrix] == null) System.out.println("niks op de huidige matrixstack plek aanwezig");

return stackedMatrix[currentMatrix];
}

public Matrix4D clearMatrix4DStack()
{
currentMatrix = 0;
stackedMatrix[currentMatrix] = new Matrix4D();

return stackedMatrix[currentMatrix];
}

public Matrix4D translate(float x, float y, float z)
{
translateMatrix.matrix[0][3] = x;
translateMatrix.matrix[1][3] = y;
translateMatrix.matrix[2][3] = z;

stackedMatrix[currentMatrix].multMatrix(translateMatrix);

return stackedMatrix[currentMatrix];
}

public Matrix4D scale(float x, float y, float z)
{
scaleMatrix.matrix[0][0] = x;
scaleMatrix.matrix[1][1] = y;
scaleMatrix.matrix[2][2] = z;

stackedMatrix[currentMatrix].multMatrix(scaleMatrix);

return stackedMatrix[currentMatrix];
}


// rotate, have to review this method for correctness
public Matrix4D rotate(float angle, float x, float y, float z)
{
int iAngle = ((int)angle) % 360;
// float sin_r = ((float)Math.sin((Math.PI/180)*angle));
// float cos_r = ((float)Math.cos((Math.PI/180)*angle));;
float sin_r = sinTable[iAngle];
float cos_r = cosTable[iAngle];
float i = 1.0f - cos_r;
float x_x_i = x * x * i;
float y_y_i = y * y * i;
float z_z_i = z * z * i;
float x_y_i = x * y * i;
float x_z_i = x * z * i;
float y_z_i = y * z * i;
float x_sin_r = x * sin_r;
float y_sin_r = y * sin_r;
float z_sin_r = z * sin_r;

Matrix4D tmpMatrix = new Matrix4D();

tmpMatrix.matrix[0][0] = x_x_i + cos_r;
tmpMatrix.matrix[1][0] = x_y_i - z_sin_r;
tmpMatrix.matrix[2][0] = x_z_i + y_sin_r;
tmpMatrix.matrix[0][1] = x_y_i + z_sin_r;
tmpMatrix.matrix[1][1] = y_y_i + cos_r;
tmpMatrix.matrix[2][1] = y_z_i - x_sin_r;
tmpMatrix.matrix[0][2] = x_z_i - y_sin_r;
tmpMatrix.matrix[1][2] = y_z_i + x_sin_r;
tmpMatrix.matrix[2][2] = z_z_i + cos_r;
tmpMatrix.matrix[3][3] = 1;

stackedMatrix[currentMatrix].multMatrix(tmpMatrix);

return stackedMatrix[currentMatrix];
}
}
-----------------------------------------------------------------
package engine3D;

public class Matrix4D implements Cloneable
{
float[][] matrix;

public Matrix4D()
{
matrix = new float[4][4];
clearMatrix();
}

void clearMatrix()
{
for (int x = 0; x < 4; x++)
for (int y = 0; y < 4; y++)
matrix[x][y]= (x==y)?1:0;
}

public Object clone()
{
Matrix4D clone = new Matrix4D();
for (int x = 0; x < 4; x++)
for (int y = 0; y < 4; y++)
clone.matrix[x][y] = matrix[x][y];

return clone;
}

public void multMatrix(Matrix4D multiplier)
{
float[][] bufMatrix = new float[4][4];

for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
bufMatrix[i][j] = matrix[i][0]*multiplier.matrix[0][j]+matrix[i][1]*multiplier.matrix[1][j]+
matrix[i][2]*multiplier.matrix[2][j]+matrix[i][3]*multiplier.matrix[3][j];
matrix = bufMatrix;
}

public void multVector(Vertex3D multiplier) // calculate new coordinates for the Vertex (same data as Vector (x,y,z)) with this Matrix
{
float tempX = multiplier.x;
float tempY = multiplier.y;
float tempZ = multiplier.z;

multiplier.x = matrix[0][0] * tempX + matrix[0][1] * tempY + matrix[0][2] * tempZ + matrix[0][3];
multiplier.y = matrix[1][0] * tempX + matrix[1][1] * tempY + matrix[1][2] * tempZ + matrix[1][3];
multiplier.z = matrix[2][0] * tempX + matrix[2][1] * tempY + matrix[2][2] * tempZ + matrix[2][3];
}

public void printMatrix()
{
for (int i = 0; i < 4; i++)
System.out.println(matrix[0][i] + " " + matrix[1][i] + " " + matrix[2][i] + " " + matrix[3][i] + " ");
}
}

Rainy, you even dont have to use matrices for it, really, just meet me sometimes

we wanna play, not watch the pictures

I'll try and explain simple matrices to you but I'm no expert.

A matrix is used to show which vertexs are connected and by how many edges. Say you had three points A,B + C and A was connected to B twice and C once you would write a matrix like this.

A A 0 B 2 C 1

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Edited by - crazy-vasey on November 21, 2000 3:05:51 PM

Thanks guys, I got it. I just wanted to know how you would handle matrix math in C (multiplying em and such). I figured it out after a bit.

L8r,
The Rainmaker