72 lines
1.6 KiB
C++
72 lines
1.6 KiB
C++
#include "pch.h"
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#include "proj.h"
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mat4_row_major proj::matrix;
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float proj::d_, proj::centerx, proj::centery;
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void proj::init(float* mat4x3, float d, float centerX, float centerY)
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{
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/*for (auto colIndex = 0; colIndex < 4; ++colIndex)
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{
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// Todo: out of bounds read from mat4x3?
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for (int rowIndex = colIndex, i = 4; i > 0; rowIndex += 4, --i)
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{
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((float*)&matrix)[rowIndex] = mat4x3[rowIndex];
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}
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}*/
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memcpy(&matrix, mat4x3, sizeof(float) * 4 * 3);
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matrix.Row3.X = 0.0;
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matrix.Row3.Y = 0.0;
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matrix.Row3.Z = 0.0;
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matrix.Row3.W = 1.0;
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d_ = d;
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centerx = centerX;
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centery = centerY;
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}
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vector3 proj::matrix_vector_multiply(const mat4_row_major& mat, const vector3& vec)
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{
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vector3 dstVec;
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const float x = vec.X, y = vec.Y, z = vec.Z;
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dstVec.X = z * mat.Row0.Z + y * mat.Row0.Y + x * mat.Row0.X + mat.Row0.W;
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dstVec.Y = z * mat.Row1.Z + y * mat.Row1.Y + x * mat.Row1.X + mat.Row1.W;
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dstVec.Z = z * mat.Row2.Z + y * mat.Row2.Y + x * mat.Row2.X + mat.Row2.W;
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return dstVec;
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}
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float proj::z_distance(const vector3& vec)
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{
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auto projVec = matrix_vector_multiply(matrix, vec);
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return maths::magnitude(projVec);
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}
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vector2i proj::xform_to_2d(const vector2& vec)
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{
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vector3 vec3{ vec.X, vec.Y, 0 };
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return xform_to_2d(vec3);
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}
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vector2i proj::xform_to_2d(const vector3& vec)
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{
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float projCoef;
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auto projVec = matrix_vector_multiply(matrix, vec);
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if (projVec.Z == 0.0f)
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projCoef = 999999.88f;
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else
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projCoef = d_ / projVec.Z;
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return
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{
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static_cast<int>(projVec.X * projCoef + centerx),
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static_cast<int>(projVec.Y * projCoef + centery)
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};
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}
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void proj::recenter(float centerX, float centerY)
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{
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centerx = centerX;
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centery = centerY;
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}
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