source/grid.cpp

   1 /* $Id$
   2
   3 This file is part of libmspgl
   4 Copyright © 2011  Mikko Rasa, Mikkosoft Productions
   5 Distributed under the LGPL
   6 */
   7
   8 #include <cmath>
   9 #include "grid.h"
  10 #include "primitivebuilder.h"
  11
  12 using namespace std;
  13
  14 namespace Msp {
  15 namespace GL {
  16
  17 GridBuilder::GridBuilder(float w, float h, unsigned u, unsigned v):
  18         origin(-w/2, -h/2, 0),
  19         side1(w, 0, 0),
  20         side2(0, h, 0),
  21         norm(0, 0, 1),
  22         binorm(0, 1, 0),
  23         u_div(u),
  24         v_div(v)
  25 {
  26         init(false);
  27 }
  28
  29 GridBuilder::GridBuilder(const Vector3 &o, const Vector3 &s, unsigned u, unsigned v):
  30         origin(o),
  31         u_div(u),
  32         v_div(v)
  33 {
  34         if(abs(s.z)<abs(s.x) && abs(s.z)<abs(s.y))
  35         {
  36                 side1 = Vector3(s.x, 0, 0);
  37                 side2 = Vector3(0, s.y, 0);
  38         }
  39         else if(abs(s.y)<abs(s.x))
  40         {
  41                 side1 = Vector3(0, 0, s.z);
  42                 side2 = Vector3(s.x, 0, 0);
  43         }
  44         else
  45         {
  46                 side1 = Vector3(0, s.y, 0);
  47                 side2 = Vector3(0, 0, s.z);
  48         }
  49         init(true);
  50 }
  51
  52 GridBuilder::GridBuilder(const Vector3 &o, const Vector3 &s1, const Vector3 &s2, unsigned u, unsigned v):
  53         origin(o),
  54         side1(s1),
  55         side2(s2),
  56         u_div(u),
  57         v_div(v)
  58 {
  59         init(true);
  60 }
  61
  62 void GridBuilder::init(bool compute_normals)
  63 {
  64         if(u_div<1)
  65                 u_div = 1;
  66         if(v_div<1)
  67                 v_div = 1;
  68
  69         if(compute_normals)
  70         {
  71                 norm.x = side1.y*side2.z-side1.z*side2.y;
  72                 norm.y = side1.z*side2.x-side1.x*side2.z;
  73                 norm.z = side1.x*side2.y-side1.y*side2.x;
  74                 float l = sqrt(norm.x*norm.x+norm.y*norm.y+norm.z*norm.z);
  75                 norm.x /= l;
  76                 norm.y /= l;
  77                 norm.z /= l;
  78
  79                 binorm.x = norm.y*side1.z-norm.z*side1.y;
  80                 binorm.y = norm.z*side1.x-norm.x*side1.z;
  81                 binorm.z = norm.x*side1.y-norm.y*side1.x;
  82                 l = sqrt(binorm.x*binorm.x+binorm.y*binorm.y+binorm.z*binorm.z);
  83                 binorm.x /= l;
  84                 binorm.y /= l;
  85                 binorm.z /= l;
  86         }
  87 }
  88
  89 void GridBuilder::build(PrimitiveBuilder &builder) const
  90 {
  91         float l1_sq = side1.x*side1.x+side1.y*side1.y+side1.z*side1.z;
  92         float l2 = side2.x*binorm.x+side2.y*binorm.y+side2.z*binorm.z;
  93         float u_scale = 1/l1_sq;
  94         float v_scale = 1/l2;
  95         adjust_texture_scale(u_scale, v_scale, sqrt(l1_sq), l2);
  96
  97         builder.normal(norm.x, norm.y, norm.z);
  98         if(tangent_attr>=0)
  99                 builder.attrib(tangent_attr, side1.x, side1.y, side1.z);
 100         if(binormal_attr>=0)
 101                 builder.attrib(tangent_attr, binorm.x, binorm.y, binorm.z);
 102
 103         for(unsigned j=0; j<=v_div; ++j)
 104         {
 105                 float v = j*1.0/v_div;
 106                 Vector3 row(origin.x+side2.x*v, origin.y+side2.y*v, origin.z+side2.z*v);
 107                 v = (row.x*binorm.x+row.y*binorm.y+row.z*binorm.z)*v_scale;
 108                 for(unsigned i=0; i<=u_div; ++i)
 109                 {
 110                         float u = i*1.0/u_div;
 111                         Vector3 p(row.x+side1.x*u, row.y+side1.y*u, row.z+side1.z*u);
 112                         u = (p.x*side1.x+p.y*side1.y+p.z*side1.z)*u_scale;
 113                         builder.texcoord(u, v);
 114                         builder.vertex(p);
 115                 }
 116         }
 117
 118         for(unsigned j=0; j<v_div; ++j)
 119         {
 120                 builder.begin(TRIANGLE_STRIP);
 121                 for(unsigned i=0; i<=u_div; ++i)
 122                 {
 123                         builder.element((j+1)*(u_div+1)+i);
 124                         builder.element(j*(u_div+1)+i);
 125                 }
 126                 builder.end();
 127         }
 128 }
 129
 130 } // namespace GL
 131 } // namespace Msp