Varjo_math.h

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// Copyright 2019-2021 Varjo Technologies Oy. All rights reserved.
 
#ifndef VARJO_MATH_H
#define VARJO_MATH_H
 
#include "Varjo_export.h"
#include "Varjo_types.h"
#include <math.h>
#include <string.h>
 
#if defined __cplusplus
extern "C" {
#endif
 
VARJO_API struct varjo_Vector3D varjo_GetEulerAngles(
    struct varjo_Matrix* matrix, varjo_EulerOrder order, varjo_RotationDirection direction, varjo_Handedness handedness);
 
VARJO_API struct varjo_Vector3D varjo_GetPosition(struct varjo_Matrix* matrix);
 
static void varjo_UpdateNearFarPlanes(double* projectionMatrix, varjo_ClipRange clipRange, double nearZ, double farZ)
{
    if (projectionMatrix == NULL) {
        return;
    }
 
    if (clipRange == varjo_ClipRangeZeroToOne) {
        if (farZ == HUGE_VAL) {
            // Normal Z-range, infinite far clip plane, D3D/Vulkan convention
            projectionMatrix[10] = -1.;
            projectionMatrix[14] = -nearZ;
        } else if (nearZ == HUGE_VAL) {
            // Inverted Z-range, infinite far clip plane, D3D/Vulkan convention
            projectionMatrix[10] = 0.;
            projectionMatrix[14] = farZ;
        } else {
            // Note: Following formula handles both cases: when farZ > nearZ and when nearZ > farZ
            projectionMatrix[10] = farZ / (nearZ - farZ);
            projectionMatrix[14] = (nearZ * farZ) / (nearZ - farZ);
        }
    } else {
        if (nearZ == HUGE_VAL || farZ == HUGE_VAL) {
            // Handles both normal and reverted Z-range in OpenGL convention in
            // the case of far clip plane located at +infinity
            projectionMatrix[10] = -1.;
            projectionMatrix[14] = nearZ <= farZ ? nearZ : farZ;
        } else {
            // Handles both normal and reverted Z-ranges in OpenGL convention
            projectionMatrix[10] = (nearZ + farZ) / (nearZ - farZ);
            projectionMatrix[14] = (2 * nearZ * farZ) / (nearZ - farZ);
        }
    }
}
static struct varjo_Matrix varjo_GetProjectionMatrix(struct varjo_FovTangents* tangents)
{
    struct varjo_Matrix varjoMatrix;
    memset(&varjoMatrix, 0, sizeof(struct varjo_Matrix));
 
    if (tangents == NULL) {
        varjoMatrix.value[0] = 1.0f;
        varjoMatrix.value[5] = 1.0f;
        varjoMatrix.value[10] = 1.0f;
        varjoMatrix.value[15] = 1.0f;
    } else {
        const double invSizeX = 1.0 / (tangents->right - tangents->left);
        const double invSizeY = 1.0 / (tangents->top - tangents->bottom);
        const double offsetX = (tangents->left + tangents->right) * invSizeX;
        const double offsetY = (tangents->bottom + tangents->top) * invSizeY;
 
        varjoMatrix.value[0] = 2.0 * invSizeX;
        varjoMatrix.value[5] = 2.0 * invSizeY;
        varjoMatrix.value[8] = offsetX;
        varjoMatrix.value[9] = offsetY;
        varjoMatrix.value[10] = -1.0;
        varjoMatrix.value[11] = -1.0;
        varjoMatrix.value[14] = -0.1;
    }
 
    return varjoMatrix;
}
 
 
#if defined __cplusplus
}
#endif
 
#endif  // VARJO_MATH_H