source/oculusriftcombiner.cpp

   1 #include <cmath>
   2 #include <msp/gl/meshbuilder.h>
   3 #include <msp/gl/texture2d.h>
   4 #include "oculusriftcombiner.h"
   5
   6 using namespace std;
   7
   8 namespace {
   9
  10 const char vs_source[] =
  11         "uniform float offset;\n"
  12         "uniform vec2 lens_center;\n"
  13         "uniform vec3 scale;\n"
  14         "varying vec2 texcoord;\n"
  15         "void main()\n"
  16         "{\n"
  17         "       gl_Position = vec4(gl_Vertex.x*0.5+offset, gl_Vertex.yzw);\n"
  18         "       texcoord = (gl_Vertex.xy*0.5+0.5-lens_center)*scale.xy;\n"
  19         "}\n";
  20
  21 const char fs_source[] =
  22         "uniform sampler2D texture;\n"
  23         "uniform vec4 distortion;\n"
  24         "uniform vec4 chromatic;\n"
  25         "uniform vec2 eye_center;\n"
  26         "uniform vec3 scale;\n"
  27         "varying vec2 texcoord;\n"
  28         "void main()\n"
  29         "{\n"
  30         "       float r_sq = dot(texcoord, texcoord);\n"
  31         "       float f = dot(distortion, vec4(1.0, r_sq, r_sq*r_sq, r_sq*r_sq*r_sq));\n"
  32         "       vec2 dtc = (texcoord*f-eye_center)/(scale.xy*scale.z)+0.5;\n"
  33         "       if(dtc.x<0.0 || dtc.y<0.0 || dtc.x>1.0 || dtc.y>1.0)\n"
  34         "               gl_FragColor = vec4(0.0);\n"
  35         "       else\n"
  36         "       {\n"
  37         "               vec2 red_dtc = (texcoord*f*(chromatic[0]+chromatic[1]*r_sq)-eye_center)/(scale.xy*scale.z)+0.5;\n"
  38         "               vec2 blue_dtc = (texcoord*f*(chromatic[2]+chromatic[3]*r_sq)-eye_center)/(scale.xy*scale.z)+0.5;\n"
  39         "               gl_FragColor = vec4(texture2D(texture, red_dtc).r, texture2D(texture, dtc).g, texture2D(texture, blue_dtc).b, 1.0);\n"
  40         "       }\n"
  41         "}\n";
  42
  43 }
  44
  45 namespace Msp {
  46 namespace VR {
  47
  48 OculusRiftCombiner::OculusRiftCombiner():
  49         mesh(GL::VERTEX2),
  50         shprog(vs_source, fs_source),
  51         // Default values copied from the SDK
  52         view_distance(0.438f),
  53         lens_separation(0.424f),
  54         eye_separation(0.42735f),
  55         fill_factor(0.95f)
  56 {
  57         width_div = 2;
  58
  59         left_shdata.uniform("texture", 0);
  60         left_shdata.uniform("offset", -0.5f);
  61         right_shdata.uniform("texture", 0);
  62         right_shdata.uniform("offset", 0.5f);
  63
  64         chromatic[0] = 1.0f;
  65         chromatic[1] = 0.0f;
  66         chromatic[2] = 1.0f;
  67         chromatic[3] = 0.0f;
  68
  69         // This will also call update_parameters
  70         set_distortion(1.0f, 0.22f, 0.24f);
  71
  72         GL::MeshBuilder bld(mesh);
  73         bld.begin(GL::TRIANGLE_STRIP);
  74         bld.vertex(-1, 1);
  75         bld.vertex(-1, -1);
  76         bld.vertex(1, 1);
  77         bld.vertex(1, -1);
  78         bld.end();
  79 }
  80
  81 void OculusRiftCombiner::set_view_distance(float d)
  82 {
  83         view_distance = d;
  84         update_parameters();
  85 }
  86
  87 void OculusRiftCombiner::set_lens_separation(float s)
  88 {
  89         lens_separation = s;
  90         update_parameters();
  91 }
  92
  93 void OculusRiftCombiner::set_eye_separation(float s)
  94 {
  95         eye_separation = s;
  96         update_parameters();
  97 }
  98
  99 void OculusRiftCombiner::set_distortion(float d0, float d1, float d2, float d3)
 100 {
 101         distortion[0] = d0;
 102         distortion[1] = d1;
 103         distortion[2] = d2;
 104         distortion[3] = d3;
 105
 106         update_parameters();
 107 }
 108
 109 void OculusRiftCombiner::set_red_aberration(float c0, float c1)
 110 {
 111         chromatic[0] = c0;
 112         chromatic[1] = c1;
 113
 114         update_parameters();
 115 }
 116
 117 void OculusRiftCombiner::set_blue_aberration(float c2, float c3)
 118 {
 119         chromatic[2] = c2;
 120         chromatic[3] = c3;
 121
 122         update_parameters();
 123 }
 124
 125 void OculusRiftCombiner::set_fill_factor(float f)
 126 {
 127         fill_factor = f;
 128         update_parameters();
 129 }
 130
 131 void OculusRiftCombiner::update_parameters()
 132 {
 133         left_shdata.uniform4("distortion", distortion);
 134         left_shdata.uniform4("chromatic", chromatic);
 135         right_shdata.uniform4("distortion", distortion);
 136         right_shdata.uniform4("chromatic", chromatic);
 137
 138         // Set lens center positions, in output texture coordinates
 139         left_shdata.uniform("lens_center", 1.0f-lens_separation, 0.5);
 140         right_shdata.uniform("lens_center", lens_separation, 0.5);
 141
 142         /* Compute distance between eye and lens centers, in sampling texture
 143         coordinates. */
 144         float eye_offset = distort((eye_separation-lens_separation)*2);
 145         left_shdata.uniform("eye_center", -eye_offset, 0.0f);
 146         right_shdata.uniform("eye_center", eye_offset, 0.0f);
 147
 148         /* Determine the necessary scaling factor to avoid quality degradation in
 149         the center of the screen. */
 150         float horiz_oversize = distort((fill_factor-lens_separation)*2)/((fill_factor-lens_separation)*2)-eye_offset;
 151         float vert_oversize = distort(1.25f*fill_factor)/(1.25f*fill_factor);
 152         oversize = min(horiz_oversize, vert_oversize);
 153
 154         left_shdata.uniform("scale", 2.0f, 2.5f, oversize);
 155         right_shdata.uniform("scale", 2.0f, 2.5f, oversize);
 156
 157         fov = Geometry::atan(oversize*0.625f/view_distance)*2.0f;
 158 }
 159
 160 float OculusRiftCombiner::distort(float r) const
 161 {
 162         float r_sq = r*r;
 163         return r*(distortion[0]+(distortion[1]+(distortion[2]+distortion[3]*r_sq)*r_sq)*r_sq);
 164 }
 165
 166 float OculusRiftCombiner::undistort(float r) const
 167 {
 168         float x = r;
 169         while(1)
 170         {
 171                 float y = distort(x);
 172                 if(abs(r-y)<1e-5)
 173                         return x;
 174
 175                 float x_sq = x*x;
 176                 float d = distortion[0]+(3*distortion[1]+(5*distortion[2]+7*distortion[3]*x_sq)*x_sq)*x_sq;
 177                 x -= (y-r)/d;
 178         }
 179 }
 180
 181 void OculusRiftCombiner::render(const GL::Texture2D &left, const GL::Texture2D &right) const
 182 {
 183         GL::Bind bind_shprog(shprog);
 184
 185         GL::Bind bind_tex(left);
 186         left_shdata.apply();
 187         mesh.draw();
 188
 189         right.bind();
 190         right_shdata.apply();
 191         mesh.draw();
 192 }
 193
 194 } // namespace VR
 195 } // namespace Msp