Improve FFmpeg hwaccel fallback, VR emulation

 - Optimize sink seeking with single video frame.
 - Small cleanups.

Signed-off-by: Andrew Opalach <andrew@akon.city>

1 files changed, 46 insertions, 0 deletions

diff --git a/src/render/shaders/vr_video.h b/src/render/shaders/vr_video.h
new file mode 100644
index 0000000..fc2d192
--- /dev/null
+++ b/src/render/shaders/vr_video.h
@@ -0,0 +1,46 @@
+#pragma once
+
+// https://gist.github.com/tesu/196db5421559de3e9555d4f9da9d847d
+// FOV:   [0 to M_PI] horizontal field of view, range is exclusive
+// YAW:   [any float] polar angle, one full revolution is 2*M_PI
+// PITCH: [any float] vertical tilt, positive is up
+// ROLL:  [any float] view rotation, positive is clockwise
+//"    const float yaw = M_PI*(-1.0+(mouse_x*2.0));\n" // 360
+static const char vr_video_shader[] = \
+"//!PARAM mouse_x\n"
+"//!TYPE float\n"
+"//!MINIMUM -0.5\n"
+"//!MAXIMUM 1.5\n"
+"0.0\n"
+"//!PARAM mouse_y\n"
+"//!TYPE float\n"
+"//!MINIMUM -0.5\n"
+"//!MAXIMUM 1.5\n"
+"0.5\n"
+"//!PARAM fov\n"
+"//!TYPE float\n"
+"//!MINIMUM 0\n"
+"//!MAXIMUM 3.141592653589793\n"
+"1.5707963267948966\n"
+"//!HOOK MAINPRESUB\n"
+"//!BIND HOOKED\n"
+"//!DESC un360\n"
+"const float M_PI = 3.141592653589793;\n"
+"vec4 hook() {\n"
+"    float yaw = M_PI*mouse_x;\n"
+"    float pitch = M_PI*(-0.5+mouse_y);\n"
+"    float roll = M_PI*0.0;\n"
+"    float t = tan(fov/2);\n"
+"    float c = cos(pitch);\n"
+"    float s = sin(pitch);\n"
+"    float r = target_size.y/target_size.x;\n"
+"    float sR = sin(roll);\n"
+"    float cR = cos(roll);\n"
+"    mat3 m = mat3(2*t*cR, 2*sR*t*r, -t*(cR+sR*r), -2*sR*t*c, 2*cR*t*c*r, t*c*(sR-cR*r)-s, -2*sR*t*s, 2*cR*t*s*r, t*s*(sR-cR*r)+c);\n"
+"    vec3 p = vec3(HOOKED_pos, 1.0) * m;\n"
+"    float theta = atan(p.x, p.z) + yaw;\n"
+"    float phi = atan(p.y, length(p.xz)) + M_PI/2;\n"
+"    float x = fract(theta / (2*M_PI));\n"
+"    float y = phi / M_PI;\n"
+"    return HOOKED_tex(vec2(x, y));\n"
+"}\n";