2018-soft-3d-renderer/src/transform.cpp

#include "matrix.h"
#include "transform.h"
#include <cmath>


// PUBLIC FUNCTIONS
Matrix Transform_Translate(float x, float y, float z)
{
    Matrix result;

    result.e41 = x;
    result.e42 = y;
    result.e43 = z;

    return result;
}

Matrix Transform_Rotate(float x, float y, float z)
{
    // YXZ Euler rotation
    float cosThetaY = cosf(y);
    float sinThetaY = sinf(y);

    Matrix tRotateY;

    tRotateY.e11 = cosThetaY;
    tRotateY.e13 = -sinThetaY;
    tRotateY.e31 = sinThetaY;
    tRotateY.e33 = cosThetaY;


    float cosThetaX = cosf(x);
    float sinThetaX = sinf(x);

    Matrix tRotateX;

    tRotateX.e22 = cosThetaX;
    tRotateX.e23 = sinThetaX;
    tRotateX.e32 = -sinThetaX;
    tRotateX.e33 = cosThetaX;


    float cosThetaZ = cosf(z);
    float sinThetaZ = sinf(z);

    Matrix tRotateZ;

    tRotateZ.e11 = cosThetaZ;
    tRotateZ.e12 = sinThetaZ;
    tRotateZ.e21 = -sinThetaZ;
    tRotateZ.e22 = cosThetaZ;


    Matrix result = tRotateY * tRotateX * tRotateZ;

    return result;
}

Matrix Transform_Scale(float s)
{
    Matrix result;

    result.e11 = s;
    result.e22 = s;
    result.e33 = s;

    return result;
}

Matrix Transform_View(Point &position, float rotation[])
{
    Matrix tInvTranslate = Transform_Translate(-position.x, -position.y, -position.z);

    Matrix tInvRotate = Transform_Rotate(-rotation[0], -rotation[1], -rotation[2]);

    Matrix result = tInvTranslate * tInvRotate;

    return result;
}

Matrix Transform_Perspective(float zoomX, float zoomY, float nearClip, float farClip)
{
    Matrix result;

    result.e11 = zoomX;
    result.e22 = zoomY;
    result.e33 = (farClip + nearClip) / (farClip - nearClip);
    result.e34 = 1;
    result.e43 = (-2.0f * farClip * nearClip) / (farClip - nearClip);

    return result;
}

Matrix Transform_Screen(float xScale, float yScale)
{
    Matrix result;

    result.e11 = xScale;
    result.e41 = xScale;
    result.e22 = -yScale;
    result.e42 = yScale;

    return result;
}