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Add Mtx_PerspStereoTilt() for stereo 3D rendering

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fincs 2015-09-16 13:29:48 +02:00
parent 0922a64ed3
commit 447c5b05bb
2 changed files with 38 additions and 0 deletions
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1
include/c3d/maths.h
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@ -71,3 +71,4 @@ void Mtx_RotateZ(C3D_Mtx* mtx, float angle, bool bRightSide);
// Special versions of the projection matrices that take the 3DS' screen orientation into account
void Mtx_OrthoTilt(C3D_Mtx* mtx, float left, float right, float bottom, float top, float near, float far);
void Mtx_PerspTilt(C3D_Mtx* mtx, float fovy, float aspect, float near, float far);
void Mtx_PerspStereoTilt(C3D_Mtx* mtx, float fovy, float aspect, float near, float far, float iod, float screen);

37
source/maths/mtx_perspstereo.c Normal file
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@ -0,0 +1,37 @@
#include <c3d/maths.h>
void Mtx_PerspStereoTilt(C3D_Mtx* mtx, float fovx, float invaspect, float near, float far, float iod, float screen)
{
// Notes:
// Once again, we are passed "fovy" and the "aspect ratio"; however the 3DS screens are sideways,
// and the formula had to be tweaked. With stereo, left/right separation becomes top/bottom separation.
// The detailed mathematical explanation is in mtx_persptilt.c.
float fovx_tan = tanf(fovx/2);
float fovx_tan_invaspect = fovx_tan*invaspect;
float shift = iod / (2*screen); // 'near' not in the numerator because it cancels out in mp.r[1].z
C3D_Mtx mp;
Mtx_Zeros(&mp);
// Build asymmetric perspective projection matrix
mp.r[0].x = 1.0f / fovx_tan;
mp.r[1].y = 1.0f / fovx_tan_invaspect;
mp.r[1].z = shift / fovx_tan_invaspect;
mp.r[2].z = (near + far) / (near - far);
mp.r[2].w = (2 * near * far) / (near - far);
mp.r[3].z = -1.0f;
// Fix depth range to [-1, 0]
C3D_Mtx mp2;
Mtx_Identity(&mp2);
mp2.r[2].z = 0.5;
mp2.r[2].w = -0.5;
Mtx_Multiply(mtx, &mp2, &mp);
// Translate to screen plane
Mtx_Translate(mtx, 0, iod/2, 0);
// Rotate the matrix one quarter of a turn CCW in order to fix the 3DS screens' orientation
Mtx_RotateZ(mtx, M_TAU/4, true);
}