[vlc-devel] [PATCH 2/4] viewpoint: add euler to 4x4 matrix conversion

[Alexandre Janniaux]

Refactor code from opengl/vout_helper and d3d11, by merging the creation of
three 4x4 rotation matrices for the shaders into only one created from the
viewpoint.
---
 include/vlc_viewpoint.h | 48 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/include/vlc_viewpoint.h b/include/vlc_viewpoint.h
index df930b3900..0b8404513c 100644
--- a/include/vlc_viewpoint.h
+++ b/include/vlc_viewpoint.h
@@ -66,4 +66,52 @@ static inline void vlc_viewpoint_reverse( vlc_viewpoint_t *p_vp )
     p_vp->roll *= -1;
 }
 
+static inline void vlc_viewpoint_to_4x4( const vlc_viewpoint_t *p_vp,
+                                         float *m )
+{
+    float s, c;
+
+    vlc_viewpoint_t vp = *p_vp;
+    vp.yaw *= M_PI; vp.pitch *= M_PI; vp.roll *= M_PI;
+    vp.yaw /= 180.f; vp.pitch /= 180.f; vp.roll /= 180.f;
+    vp.yaw += M_PI_2;
+
+    s = sinf(vp.pitch);
+    c = cosf(vp.pitch);
+    float x_rot[4][4] = {
+        { 1.f,    0.f,    0.f,    0.f },
+        { 0.f,    c,      -s,      0.f },
+        { 0.f,    s,      c,      0.f },
+        { 0.f,    0.f,    0.f,    1.f } };
+
+    s = sinf(vp.yaw);
+    c = cosf(vp.yaw);
+    float y_rot[4][4] = {
+        { c,      0.f,    s,     0.f },
+        { 0.f,    1.f,    0.f,    0.f },
+        { -s,      0.f,    c,      0.f },
+        { 0.f,    0.f,    0.f,    1.f } };
+
+    s = sinf(vp.roll);
+    c = cosf(vp.roll);
+    float z_rot[4][4] = {
+        { c,      s,      0.f,    0.f },
+        { -s,     c,      0.f,    0.f },
+        { 0.f,    0.f,    1.f,    0.f },
+        { 0.f,    0.f,    0.f,    1.f } };
+
+    /**
+     * Column-major matrix multiplication mathematically equal to
+     * z_rot * x_rot * y_rot
+     */
+    memset(m, 0, 16 * sizeof(float));
+    for (int i=0; i<4; ++i)
+    for (int j=0; j<4; ++j)
+    for (int k=0; k<4; ++k)
+    for (int l=0; l<4; ++l)
+    {
+        m[4*i+l] += y_rot[i][j] * x_rot[j][k] * z_rot[k][l];
+    }
+}
+
 #endif /* VLC_VIEWPOINT_H_ */
-- 
2.20.1