Add a StereoCombiner subclass for the Oculus Rift

[libs/vr.git] / source / oculusriftcombiner.cpp

diff --git a/source/oculusriftcombiner.cpp b/source/oculusriftcombiner.cpp
new file mode 100644 (file)
index 0000000..9d985d9
--- /dev/null
+++ b/source/oculusriftcombiner.cpp
@@ -0,0 +1,170 @@
+#include <cmath>
+#include "meshbuilder.h"
+#include "oculusriftcombiner.h"
+#include "texture2d.h"
+
+using namespace std;
+
+namespace {
+
+const char vs_source[] =
+       "uniform float offset;\n"
+       "uniform vec2 lens_center;\n"
+       "uniform vec3 scale;\n"
+       "varying vec2 texcoord;\n"
+       "void main()\n"
+       "{\n"
+       "       gl_Position = vec4(gl_Vertex.x*0.5+offset, gl_Vertex.yzw);\n"
+       "       texcoord = (gl_Vertex.xy*0.5+0.5-lens_center)*scale.xy;\n"
+       "}\n";
+
+const char fs_source[] =
+       "uniform sampler2D texture;\n"
+       "uniform vec4 distortion;\n"
+       "uniform vec2 eye_center;\n"
+       "uniform vec3 scale;\n"
+       "varying vec2 texcoord;\n"
+       "vec2 distort(vec2 coord)\n"
+       "{\n"
+       "       float r_sq = dot(coord, coord);\n"
+       "       return coord*dot(distortion, vec4(1.0, r_sq, r_sq*r_sq, r_sq*r_sq*r_sq));\n"
+       "}\n"
+       "void main()\n"
+       "{\n"
+       "       vec2 dtc = (distort(texcoord)-eye_center)/(scale.xy*scale.z)+0.5;\n"
+       "       if(dtc.x<0.0 || dtc.y<0.0 || dtc.x>1.0 || dtc.y>1.0)\n"
+       "               gl_FragColor = vec4(0.0);\n"
+       "       else\n"
+       "               gl_FragColor = texture2D(texture, dtc);\n"
+       "}\n";
+
+}
+
+namespace Msp {
+namespace GL {
+
+OculusRiftCombiner::OculusRiftCombiner():
+       mesh(VERTEX2),
+       shprog(vs_source, fs_source),
+       // Default values copied from the SDK
+       view_distance(0.438f),
+       lens_separation(0.424f),
+       eye_separation(0.42735f),
+       fill_factor(0.95f)
+{
+       width_div = 2;
+
+       left_shdata.uniform("texture", 0);
+       left_shdata.uniform("offset", -0.5f);
+       right_shdata.uniform("texture", 0);
+       right_shdata.uniform("offset", 0.5f);
+
+       // This will also call update_parameters
+       set_distortion(1.0f, 0.22f, 0.24f);
+
+       MeshBuilder bld(mesh);
+       bld.begin(TRIANGLE_STRIP);
+       bld.vertex(-1, 1);
+       bld.vertex(-1, -1);
+       bld.vertex(1, 1);
+       bld.vertex(1, -1);
+       bld.end();
+}
+
+void OculusRiftCombiner::set_view_distance(float d)
+{
+       view_distance = d;
+       update_parameters();
+}
+
+void OculusRiftCombiner::set_lens_separation(float s)
+{
+       lens_separation = s;
+       update_parameters();
+}
+
+void OculusRiftCombiner::set_eye_separation(float s)
+{
+       eye_separation = s;
+       update_parameters();
+}
+
+void OculusRiftCombiner::set_distortion(float d0, float d1, float d2, float d3)
+{
+       distortion[0] = d0;
+       distortion[1] = d1;
+       distortion[2] = d2;
+       distortion[3] = d3;
+
+       update_parameters();
+}
+
+void OculusRiftCombiner::set_fill_factor(float f)
+{
+       fill_factor = f;
+       update_parameters();
+}
+
+void OculusRiftCombiner::update_parameters()
+{
+       left_shdata.uniform4("distortion", distortion);
+       right_shdata.uniform4("distortion", distortion);
+
+       // Set lens center positions, in output texture coordinates
+       left_shdata.uniform("lens_center", 1.0f-lens_separation, 0.5);
+       right_shdata.uniform("lens_center", lens_separation, 0.5);
+
+       /* Compute distance between eye and lens centers, in sampling texture
+       coordinates. */
+       float eye_offset = distort((eye_separation-lens_separation)*2);
+       left_shdata.uniform("eye_center", -eye_offset, 0.0f);
+       right_shdata.uniform("eye_center", eye_offset, 0.0f);
+
+       /* Determine the necessary scaling factor to avoid quality degradation in
+       the center of the screen. */
+       float horiz_oversize = distort((fill_factor-lens_separation)*2)-eye_offset;
+       float vert_oversize = distort(1.25f*fill_factor)/(1.25f*fill_factor);
+       oversize = min(horiz_oversize, vert_oversize);
+
+       left_shdata.uniform("scale", 2.0f, 2.5f, oversize);
+       right_shdata.uniform("scale", 2.0f, 2.5f, oversize);
+
+       fov = Geometry::atan(oversize*0.625f/view_distance)*2.0f;
+}
+
+float OculusRiftCombiner::distort(float r) const
+{
+       float r_sq = r*r;
+       return r*(distortion[0]+(distortion[1]+(distortion[2]+distortion[3]*r_sq)*r_sq)*r_sq);
+}
+
+float OculusRiftCombiner::undistort(float r) const
+{
+       float x = r;
+       while(1)
+       {
+               float y = distort(x);
+               if(abs(r-y)<1e-5)
+                       return x;
+
+               float x_sq = x*x;
+               float d = distortion[0]+(3*distortion[1]+(5*distortion[2]+7*distortion[3]*x_sq)*x_sq)*x_sq;
+               x -= (y-r)/d;
+       }
+}
+
+void OculusRiftCombiner::render(const Texture2D &left, const Texture2D &right) const
+{
+       Bind bind_shprog(shprog);
+
+       Bind bind_tex(left);
+       left_shdata.apply();
+       mesh.draw();
+
+       right.bind();
+       right_shdata.apply();
+       mesh.draw();
+}
+
+} // namespace GL
+} // namespace Msp