我试图通过OpenGl从屏幕坐标获取世界坐标。我做了一些研究，但返回的值不一致。事实上，在我的世界里，我有一个Z = 0的表面，我希望在该表面上有一个点的三维坐标，所以Z = 0。在这里我的研究：
float cursZ = 1;
long posX, posY, posZ = 0;
int viewport[4];
viewport[0] = Originex;
viewport[1] = Originey;
viewport[2] = largeFen;
viewport[3] = hautFen;
CMatrix4 modelView;
CMatrix4 proj;
CMatrix4 A;
CMatrix4 out;
typeCoorDepl proche = 100.;
typeCoorDepl loin = largeFen + hautFen;
Renderer.GetMatrix(MAT_MODELVIEW, modelView);
Renderer.GetMatrix(MAT_PROJECTION, proj);
modelView.LookAt(TVector3T(sendAngleX, angleY, SendAngleZ), TVector3T(0, 0, 0));
switch (modeVue)// get MAT_PROJECTION
{
case 1: // mode isometrique rotation centree sur l'ecran
proj.OrthoOffCenter(-(largeFen / 2.0f), (hautFen / 2.0f), (largeFen / 2.0f), -(hautFen / 2.0f), proche, loin);
break;
case 2: // mode conique rotation centree sur l'ecran
proj.PerspectiveFOV((70.0*pi / 180) / 2, largeFen / hautFen, proche, loin);
break;
case 3: // mode isometrique rotation centree sur l'ecran
proj.OrthoOffCenter(-(largeFen / 2.0f), (hautFen / 2.0f), (largeFen / 2.0f), -(hautFen / 2.0f), proche, loin);
break;
case 4: // mode conique rotation centree sur l'objet et non sur l'ecran
proj.PerspectiveFOV((70.0*pi / 180), largeFen / hautFen, proche, loin);
break;
default:
break;
}
cursY = hautFen - cursY; // windows start from top-left as openGL from bottom-left
double posx, posy, posz;
float m[16];//, A[16];
float in[4];//, out[4];
A = proj*modelView;
A.Inverse();
in[0] = cursX;
in[1] = cursY;
in[2] = cursZ;
in[3] = 1.0;
/* Map x and y from window coordinates */
in[0] = (in[0] - viewport[0]) / viewport[2];
in[1] = (in[1] - viewport[1]) / viewport[3];
/* Map to range -1 to 1 */
in[0] = in[0] * 2 - 1;
in[1] = in[1] * 2 - 1;
in[2] = in[2] * 2 - 1;
CMatrix4 forTestIn;
forTestIn.a11 = in[0];
forTestIn.a12 = in[1];
forTestIn.a13 = in[2];
forTestIn.a14 = in[3];
out = A*forTestIn;
out.a11 /= out.a14;
out.a12 /= out.a14;
out.a13 /= out.a14;
*finPosX = out.a11;
*finPosY = out.a12;
*finPosZ = out.a13;
这里我的OrthoOffCenter和PerspectiveFOV功能：
inline void CMatrix4::OrthoOffCenter(typeCoorDepl Left, typeCoorDepl Top, typeCoorDepl Right, typeCoorDepl Bottom, typeCoorDepl Near, typeCoorDepl Far)
{
a11 = 2 / (Right - Left); a12 = 0.0f; a13 = 0.0f; a14 = (Left + Right) / (Left - Right);
a21 = 0.0f; a22 = 2 / (Top - Bottom); a23 = 0.0f; a24 = (Bottom + Top) / (Bottom - Top);
// a31 = 0.0f; a32 = 0.0f; a33 = -2/(Far - Near); a34 = (Near + Far) / (Far - Near);
// substitution Far/Near cause pb depth buffer
a31 = 0.0f; a32 = 0.0f; a33 = -2/(Near - Far); a34 = (Far + Near) / (Near - Far);
a41 = 0.0f; a42 = 0.0f; a43 = 0.0f; a44 = 1.0f;
}
inline void CMatrix4::PerspectiveFOV(typeCoorDepl Fov, typeCoorDepl Ratio, typeCoorDepl Near, typeCoorDepl Far)
{
typeCoorDepl YScale = 1.0f / std::tan(Fov / 2);
typeCoorDepl XScale = YScale / Ratio;
typeCoorDepl Coeff = Far / (Far - Near);
a11 = XScale; a12 = 0.0f; a13 = 0.0f; a14 = 0.0f;
a21 = 0.0f; a22 = YScale; a23 = 0.0f; a24 = 0.0f;
a31 = 0.0f; a32 = 0.0f; a33 = Coeff; a34 = Near * -Coeff;
a41 = 0.0f; a42 = 0.0f; a43 = 1.0f; a44 = 0.0f;
// nb : agir sur a14, a24 déplace le centre "de rotation"
}
答案 0 :(得分：1)
如果在视口上绘制某些内容，则会执行以下转换：
在此变换之后，坐标位于标准化设备坐标空间（NDC）中。 NDC的范围为（-1，-1，-1）到（1,1,1）。
如果要将标准化设备坐标（NDC）中的点转换回世界空间，则必须进行完全反向转换：
查看Stack Overflow Question inverting a 4x4 matrix的答案，了解如何计算逆矩阵：
template < typename T_MD, typename T_MS = T_MD, typename T_SCALAR = float >
void mat44_inverse( T_MD &res, const T_MS &m )
{
T_SCALAR Coef00 = (T_SCALAR)(m[2][2] * m[3][3] - m[3][2] * m[2][3]);
T_SCALAR Coef02 = (T_SCALAR)(m[1][2] * m[3][3] - m[3][2] * m[1][3]);
T_SCALAR Coef03 = (T_SCALAR)(m[1][2] * m[2][3] - m[2][2] * m[1][3]);
T_SCALAR Coef04 = (T_SCALAR)(m[2][1] * m[3][3] - m[3][1] * m[2][3]);
T_SCALAR Coef06 = (T_SCALAR)(m[1][1] * m[3][3] - m[3][1] * m[1][3]);
T_SCALAR Coef07 = (T_SCALAR)(m[1][1] * m[2][3] - m[2][1] * m[1][3]);
T_SCALAR Coef08 = (T_SCALAR)(m[2][1] * m[3][2] - m[3][1] * m[2][2]);
T_SCALAR Coef10 = (T_SCALAR)(m[1][1] * m[3][2] - m[3][1] * m[1][2]);
T_SCALAR Coef11 = (T_SCALAR)(m[1][1] * m[2][2] - m[2][1] * m[1][2]);
T_SCALAR Coef12 = (T_SCALAR)(m[2][0] * m[3][3] - m[3][0] * m[2][3]);
T_SCALAR Coef14 = (T_SCALAR)(m[1][0] * m[3][3] - m[3][0] * m[1][3]);
T_SCALAR Coef15 = (T_SCALAR)(m[1][0] * m[2][3] - m[2][0] * m[1][3]);
T_SCALAR Coef16 = (T_SCALAR)(m[2][0] * m[3][2] - m[3][0] * m[2][2]);
T_SCALAR Coef18 = (T_SCALAR)(m[1][0] * m[3][2] - m[3][0] * m[1][2]);
T_SCALAR Coef19 = (T_SCALAR)(m[1][0] * m[2][2] - m[2][0] * m[1][2]);
T_SCALAR Coef20 = (T_SCALAR)(m[2][0] * m[3][1] - m[3][0] * m[2][1]);
T_SCALAR Coef22 = (T_SCALAR)(m[1][0] * m[3][1] - m[3][0] * m[1][1]);
T_SCALAR Coef23 = (T_SCALAR)(m[1][0] * m[2][1] - m[2][0] * m[1][1]);
_TMat44Helper<T_SCALAR> Fac0(Coef00, Coef00, Coef02, Coef03);
_TMat44Helper<T_SCALAR> Fac1(Coef04, Coef04, Coef06, Coef07);
_TMat44Helper<T_SCALAR> Fac2(Coef08, Coef08, Coef10, Coef11);
_TMat44Helper<T_SCALAR> Fac3(Coef12, Coef12, Coef14, Coef15);
_TMat44Helper<T_SCALAR> Fac4(Coef16, Coef16, Coef18, Coef19);
_TMat44Helper<T_SCALAR> Fac5(Coef20, Coef20, Coef22, Coef23);
_TMat44Helper<T_SCALAR> Vec0((T_SCALAR)m[1][0], (T_SCALAR)m[0][0], (T_SCALAR)m[0][0], (T_SCALAR)m[0][0]);
_TMat44Helper<T_SCALAR> Vec1((T_SCALAR)m[1][1], (T_SCALAR)m[0][1], (T_SCALAR)m[0][1], (T_SCALAR)m[0][1]);
_TMat44Helper<T_SCALAR> Vec2((T_SCALAR)m[1][2], (T_SCALAR)m[0][2], (T_SCALAR)m[0][2], (T_SCALAR)m[0][2]);
_TMat44Helper<T_SCALAR> Vec3((T_SCALAR)m[1][3], (T_SCALAR)m[0][3], (T_SCALAR)m[0][3], (T_SCALAR)m[0][3]);
_TMat44Helper<T_SCALAR> Inv0(Vec1 * Fac0 - Vec2 * Fac1 + Vec3 * Fac2);
_TMat44Helper<T_SCALAR> Inv1(Vec0 * Fac0 - Vec2 * Fac3 + Vec3 * Fac4);
_TMat44Helper<T_SCALAR> Inv2(Vec0 * Fac1 - Vec1 * Fac3 + Vec3 * Fac5);
_TMat44Helper<T_SCALAR> Inv3(Vec0 * Fac2 - Vec1 * Fac4 + Vec2 * Fac5);
_TMat44Helper<T_SCALAR> SignA((T_SCALAR)+1.0, (T_SCALAR)-1.0, (T_SCALAR)+1.0, (T_SCALAR)-1.0);
_TMat44Helper<T_SCALAR> SignB((T_SCALAR)-1.0, (T_SCALAR)+1.0, (T_SCALAR)-1.0, (T_SCALAR)+1.0);
std::array< _TMat44Helper<T_SCALAR>, 4 > Inverse{ Inv0 * SignA, Inv1 * SignB, Inv2 * SignA, Inv3 * SignB };
_TMat44Helper<T_SCALAR> Row0(Inverse[0][0], Inverse[1][0], Inverse[2][0], Inverse[3][0]);
_TMat44Helper<T_SCALAR> Dot0( Row0 );
Dot0 = Dot0 * _TMat44Helper<T_SCALAR>( (T_SCALAR)m[0][0], (T_SCALAR)m[0][1], (T_SCALAR)m[0][2], (T_SCALAR)m[0][3] );
T_SCALAR Dot1 = (Dot0[0] + Dot0[1]) + (Dot0[2] + Dot0[3]);
T_SCALAR OneOverDeterminant = static_cast<T_SCALAR>(1.0) / Dot1;
for ( int inx1 = 0; inx1 < 4; inx1 ++ )
{
for ( int inx2 = 0; inx2 < 4; inx2 ++ )
res[inx1][inx2] = Inverse[inx1][inx2] * OneOverDeterminant;
}
}
template< typename SCALAR_TYPE = float >
struct _TMat44Helper
{
_TMat44Helper( void ) {}
_TMat44Helper( SCALAR_TYPE x, SCALAR_TYPE y, SCALAR_TYPE z, SCALAR_TYPE w ) : m_v( { x, y, z, w } ){}
_TMat44Helper( const std::array< SCALAR_TYPE, 4 > & v ) : m_v( v ) {}
_TMat44Helper( const SCALAR_TYPE v[4] ) { std::memcpy( m_v.data(), v, 4 * sizeof( SCALAR_TYPE ) ); }
_TMat44Helper( const _TMat44Helper &src ) : m_v( src.m_v ) {}
_TMat44Helper & operator = ( const _TMat44Helper<SCALAR_TYPE> &src ) { m_v = src.m_v; return *this; }
SCALAR_TYPE & operator[](int inx) { return m_v[inx]; }
template< typename SCALAR_TYPE_OP >
_TMat44Helper<SCALAR_TYPE> operator *( SCALAR_TYPE_OP s )
{
_TMat44Helper res;
for ( int inx = 0; inx < 4; inx ++ )
res.m_v[inx] = m_v[inx] * (SCALAR_TYPE)s;
return res;
}
template< typename SCALAR_TYPE_OP >
_TMat44Helper<SCALAR_TYPE> operator +( const _TMat44Helper<SCALAR_TYPE_OP> &b )
{
_TMat44Helper<SCALAR_TYPE> res;
for ( int inx = 0; inx < 4; inx ++ )
res.m_v[inx] = m_v[inx] + (SCALAR_TYPE)b.m_v[inx];
return res;
}
template< typename SCALAR_TYPE_OP >
_TMat44Helper<SCALAR_TYPE> operator -( const _TMat44Helper<SCALAR_TYPE_OP> &b )
{
_TMat44Helper<SCALAR_TYPE> res;
for ( int inx = 0; inx < 4; inx ++ )
res.m_v[inx] = m_v[inx] - (SCALAR_TYPE)b.m_v[inx];
return res;
}
template< typename SCALAR_TYPE_OP >
_TMat44Helper<SCALAR_TYPE> operator *( const _TMat44Helper<SCALAR_TYPE_OP> &b )
{
_TMat44Helper<SCALAR_TYPE> res;
for ( int inx = 0; inx < 4; inx ++ )
res.m_v[inx] = m_v[inx] * (SCALAR_TYPE)b.m_v[inx];
return res;
}
std::array< SCALAR_TYPE, 4 > m_v;
};
要将点从视口（屏幕）坐标映射到NDC，您必须将X坐标和Y坐标映射到范围（-1.0,1.0）。 Z坐标更棘手，为此你必须访问深度缓冲区（深度缓冲区可以渲染到纹理）。 读取XY位置的深度并将其转换为NDC：
X_ndc = X_screen * 2.0 / VP_sizeX - 1.0;
Y_ndc = Y_screen * 2.0 / VP_sizeY - 1.0;
Z_ndc = 2.0 * depth - 1.0;
在您的情况下，您只有2D几何体和正交投影，因此您不必关心深度，因为Z坐标始终为0.0。
如果通过投影矩阵（或逆投影矩阵）变换点，您将在齐次坐标系中得到一个点。要将点从齐次坐标系转换为笛卡尔坐标系，必须按重量划分X，Y和Z坐标。 具有均匀4 * 4矩阵的笛卡尔坐标系中点的一般变换函数可能如下所示：
using TVec3 = std::array<float, 3>;
using TVec4 = std::array<float, 4>;
using TMat4 = std::array<TVec4, 4>;
TVec3 Transform( const TVec3 &vec, const TMat4 &mat )
{
h {
vec[0] * mat[0][0] + vec[1] * mat[1][0] + vec[2] * mat[2][0] + mat[3][0],
vec[0] * mat[0][1] + vec[1] * mat[1][1] + vec[2] * mat[2][1] + mat[3][1],
vec[0] * mat[0][2] + vec[1] * mat[1][2] + vec[2] * mat[2][2] + mat[3][2],
vec[0] * mat[0][3] + vec[1] * mat[1][3] + vec[2] * mat[2][3] + mat[3][3]
};
if ( h[3] == 0.0 )
return TVec3{ 1.0e99 }; // division by zero
return TVec3{ h[0]/h[3], h[1]/h[3], h[2]/h[3] };
}
请参阅以下WebGL示例，其中通过计算从屏幕坐标到模型坐标的位置，找到鼠标悬停的对象的颜色。
<script type="text/javascript">
draw_vert =
"precision mediump float; \n" +
"attribute vec2 inPos; \n" +
"uniform mat4 u_projectionMat44;" +
"uniform mat4 u_modelViewMat44;" +
"void main()" +
"{" +
" vec4 viewPos = u_modelViewMat44 * vec4( inPos.xy, 0.0, 1.0 );" +
" gl_Position = u_projectionMat44 * viewPos;" +
"}";
draw_frag =
"precision mediump float; \n" +
"uniform vec3 u_color;" +
"void main()" +
"{" +
" gl_FragColor = vec4( u_color.xyz, 1.0 );" +
"}";
glArrayType = typeof Float32Array !="undefined" ? Float32Array : ( typeof WebGLFloatArray != "undefined" ? WebGLFloatArray : Array );
function IdentityMat44() {
var m = new glArrayType(16);
m[0] = 1; m[1] = 0; m[2] = 0; m[3] = 0;
m[4] = 0; m[5] = 1; m[6] = 0; m[7] = 0;
m[8] = 0; m[9] = 0; m[10] = 1; m[11] = 0;
m[12] = 0; m[13] = 0; m[14] = 0; m[15] = 1;
return m;
};
function RotateAxis(matA, angRad, axis) {
var aMap = [ [1, 2], [2, 0], [0, 1] ];
var a0 = aMap[axis][0], a1 = aMap[axis][1];
var sinAng = Math.sin(angRad), cosAng = Math.cos(angRad);
var matB = new glArrayType(16);
for ( var i = 0; i < 16; ++ i ) matB[i] = matA[i];
for ( var i = 0; i < 3; ++ i ) {
matB[a0*4+i] = matA[a0*4+i] * cosAng + matA[a1*4+i] * sinAng;
matB[a1*4+i] = matA[a0*4+i] * -sinAng + matA[a1*4+i] * cosAng;
}
return matB;
}
function Translate( matA, trans ) {
var matB = new glArrayType(16);
for ( var i = 0; i < 16; ++ i ) matB[i] = matA[i];
for ( var i = 0; i < 3; ++ i )
matB[12+i] = matA[i] * trans[0] + matA[4+i] * trans[1] + matA[8+i] * trans[2] + matA[12+i];
return matB;
}
function Scale( matA, scale ) {
var matB = new glArrayType(16);
for ( var i = 0; i < 16; ++ i ) matB[i] = matA[i];
for ( var a = 0; a < 4; ++ a )
for ( var i = 0; i < 3; ++ i )
matB[a*4+i] = matA[a*4+i] * scale[0];
return matB;
}
Ortho = function( l, r, t, b, n, f ) {
var fn = f + n;
var f_n = f - n;
var m = IdentityMat44();
m[0] = 2/(r-l); m[1] = 0; m[2] = 0; m[3] = 0;
m[4] = 0; m[5] = 2/(t-b); m[6] = 0; m[7] = 0;
m[8] = 0; m[9] = 0; m[10] = -2 / f_n; m[11] = -fn / f_n;
m[12] = 0; m[13] = 0; m[14] = 0; m[15] = 1;
return m;
}
vec4_add = function( a, b ) { return [ a[0]+b[0], a[1]+b[1], a[2]+b[2], a[3]+b[3] ]; }
vec4_sub = function( a, b ) { return [ a[0]-b[0], a[1]-b[1], a[2]-b[2], a[3]-b[3] ]; }
vec4_mul = function( a, b ) { return [ a[0]*b[0], a[1]*b[1], a[2]*b[2], a[3]*b[3] ]; }
vec4_scale = function( a, s ) { return [ a[0]*s, a[1]*s, a[2]*s, a[3]*s ]; }
mat44_inverse = function( m ) {
var Coef00 = m[2*4+2] * m[3*4+3] - m[3*4+2] * m[2*4+3];
var Coef02 = m[1*4+2] * m[3*4+3] - m[3*4+2] * m[1*4+3];
var Coef03 = m[1*4+2] * m[2*4+3] - m[2*4+2] * m[1*4+3];
var Coef04 = m[2*4+1] * m[3*4+3] - m[3*4+1] * m[2*4+3];
var Coef06 = m[1*4+1] * m[3*4+3] - m[3*4+1] * m[1*4+3];
var Coef07 = m[1*4+1] * m[2*4+3] - m[2*4+1] * m[1*4+3];
var Coef08 = m[2*4+1] * m[3*4+2] - m[3*4+1] * m[2*4+2];
var Coef10 = m[1*4+1] * m[3*4+2] - m[3*4+1] * m[1*4+2];
var Coef11 = m[1*4+1] * m[2*4+2] - m[2*4+1] * m[1*4+2];
var Coef12 = m[2*4+0] * m[3*4+3] - m[3*4+0] * m[2*4+3];
var Coef14 = m[1*4+0] * m[3*4+3] - m[3*4+0] * m[1*4+3];
var Coef15 = m[1*4+0] * m[2*4+3] - m[2*4+0] * m[1*4+3];
var Coef16 = m[2*4+0] * m[3*4+2] - m[3*4+0] * m[2*4+2];
var Coef18 = m[1*4+0] * m[3*4+2] - m[3*4+0] * m[1*4+2];
var Coef19 = m[1*4+0] * m[2*4+2] - m[2*4+0] * m[1*4+2];
var Coef20 = m[2*4+0] * m[3*4+1] - m[3*4+0] * m[2*4+1];
var Coef22 = m[1*4+0] * m[3*4+1] - m[3*4+0] * m[1*4+1];
var Coef23 = m[1*4+0] * m[2*4+1] - m[2*4+0] * m[1*4+1];
var Fac0 = [Coef00, Coef00, Coef02, Coef03];
var Fac1 = [Coef04, Coef04, Coef06, Coef07];
var Fac2 = [Coef08, Coef08, Coef10, Coef11];
var Fac3 = [Coef12, Coef12, Coef14, Coef15];
var Fac4 = [Coef16, Coef16, Coef18, Coef19];
var Fac5 = [Coef20, Coef20, Coef22, Coef23];
var Vec0 = [ m[1*4+0], m[0*4+0], m[0*4+0], m[0*4+0] ];
var Vec1 = [ m[1*4+1], m[0*4+1], m[0*4+1], m[0*4+1] ];
var Vec2 = [ m[1*4+2], m[0*4+2], m[0*4+2], m[0*4+2] ];
var Vec3 = [ m[1*4+3], m[0*4+3], m[0*4+3], m[0*4+3] ];
var Inv0 = vec4_add( vec4_sub( vec4_mul(Vec1, Fac0), vec4_mul(Vec2, Fac1) ), vec4_mul( Vec3, Fac2 ) );
var Inv1 = vec4_add( vec4_sub( vec4_mul(Vec0, Fac0), vec4_mul(Vec2, Fac3) ), vec4_mul( Vec3, Fac4 ) );
var Inv2 = vec4_add( vec4_sub( vec4_mul(Vec0, Fac1), vec4_mul(Vec1, Fac3) ), vec4_mul( Vec3, Fac5 ) );
var Inv3 = vec4_add( vec4_sub( vec4_mul(Vec0, Fac2), vec4_mul(Vec1, Fac4) ), vec4_mul( Vec2, Fac5 ) );
var SignA = [+1.0, -1.0, +1.0, -1.0];
var SignB = [-1.0, +1.0, -1.0, +1.0];
var Inverse = [ vec4_mul(Inv0, SignA), vec4_mul(Inv1, SignB), vec4_mul(Inv2, SignA), vec4_mul(Inv3, SignB) ];
var Row0 = [Inverse[0][0], Inverse[1][0], Inverse[2][0], Inverse[3][0] ];
var Dot0 = [Row0[0], Row0[1], Row0[2], Row0[3] ];
Dot0 = vec4_mul( Dot0, [ m[0], m[1], m[2], m[3] ] );
var Dot1 = (Dot0[0] + Dot0[1]) + (Dot0[2] + Dot0[3]);
var OneOverDeterminant = 1 / Dot1;
var res = IdentityMat44();
for ( var inx1 = 0; inx1 < 4; inx1 ++ ) {
for ( var inx2 = 0; inx2 < 4; inx2 ++ )
res[inx1*4+inx2] = Inverse[inx1][inx2] * OneOverDeterminant;
}
return res;
}
Transform = function(vec, mat) {
var h = [
vec[0] * mat[0*4+0] + vec[1] * mat[1*4+0] + vec[2] * mat[2*4+0] + mat[3*4+0],
vec[0] * mat[0*4+1] + vec[1] * mat[1*4+1] + vec[2] * mat[2*4+1] + mat[3*4+1],
vec[0] * mat[0*4+2] + vec[1] * mat[1*4+2] + vec[2] * mat[2*4+2] + mat[3*4+2],
vec[0] * mat[0*4+3] + vec[1] * mat[1*4+3] + vec[2] * mat[2*4+3] + mat[3*4+3] ]
if ( h[3] == 0.0 )
return [0, 0, 0]
return [ h[0]/h[3], h[1]/h[3], h[2]/h[3] ];
}
// shader program object
var ShaderProgram = {};
ShaderProgram.Create = function( shaderList, uniformNames ) {
var shaderObjs = [];
for ( var i_sh = 0; i_sh < shaderList.length; ++ i_sh ) {
var shderObj = this.CompileShader( shaderList[i_sh].source, shaderList[i_sh].stage );
if ( shderObj == 0 )
return 0;
shaderObjs.push( shderObj );
}
var progObj = this.LinkProgram( shaderObjs )
if ( progObj != 0 ) {
progObj.unifomLocation = {};
for ( var i_n = 0; i_n < uniformNames.length; ++ i_n ) {
var name = uniformNames[i_n];
progObj.unifomLocation[name] = gl.getUniformLocation( progObj, name );
}
}
return progObj;
}
ShaderProgram.Use = function( progObj ) { gl.useProgram( progObj ); }
ShaderProgram.SetUniformInt = function( progObj, name, val ) { gl.uniform1i( progObj.unifomLocation[name], val ); }
ShaderProgram.SetUniform2f = function( progObj, name, arr ) { gl.uniform2fv( progObj.unifomLocation[name], arr ); }
ShaderProgram.SetUniform3f = function( progObj, name, arr ) { gl.uniform3fv( progObj.unifomLocation[name], arr ); }
ShaderProgram.SetUniformMat44 = function( progObj, name, mat ) { gl.uniformMatrix4fv( progObj.unifomLocation[name], false, mat ); }
ShaderProgram.CompileShader = function( source, shaderStage ) {
var shaderObj = gl.createShader( shaderStage );
gl.shaderSource( shaderObj, source );
gl.compileShader( shaderObj );
var status = gl.getShaderParameter( shaderObj, gl.COMPILE_STATUS );
if ( !status ) alert(gl.getShaderInfoLog(shaderObj));
return status ? shaderObj : 0;
}
ShaderProgram.LinkProgram = function( shaderObjs ) {
var prog = gl.createProgram();
for ( var i_sh = 0; i_sh < shaderObjs.length; ++ i_sh )
gl.attachShader( prog, shaderObjs[i_sh] );
gl.linkProgram( prog );
status = gl.getProgramParameter( prog, gl.LINK_STATUS );
if ( !status ) alert("Could not initialise shaders");
gl.useProgram( null );
return status ? prog : 0;
}
function drawScene(){
var canvas = document.getElementById( "camera-canvas" );
var currentTime = Date.now();
var deltaMS = currentTime - startTime;
var aspect = canvas.width / canvas.height;
var matOrtho = Ortho( -aspect, aspect, 1, -1, -1, 1 );
var matOrthoInv = mat44_inverse( matOrtho )
gl.viewport( 0, 0, canvas.width, canvas.height );
gl.enable( gl.DEPTH_TEST );
gl.clearColor( 0.0, 0.0, 0.0, 1.0 );
gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
ShaderProgram.Use( progDraw );
gl.enableVertexAttribArray( progDraw.inPos );
gl.bindBuffer( gl.ARRAY_BUFFER, bufObj.pos );
gl.vertexAttribPointer( progDraw.inPos, 2, gl.FLOAT, false, 0, 0 );
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufObj.inx );
ShaderProgram.SetUniformMat44( progDraw, "u_projectionMat44", matOrtho );
var col = [ [1.0,0.0,0.0], [1.0,1.0,0.0], [0.0,0.0,1.0] ];
var invMat = []
for ( var i = 0; i < 3; ++ i ) {
var modelMat = Scale( IdentityMat44(), [ 0.3, 0.3, 0.3] );
var angRad = CalcAng( currentTime, 20.0 ) + i * Math.PI * 2 / 3;
var sinAng = Math.sin(angRad), cosAng = Math.cos(angRad);
modelMat[12] = cosAng * 0.6;
modelMat[13] = sinAng * 0.6;
invMat.push( mat44_inverse( modelMat ) );
ShaderProgram.SetUniformMat44( progDraw, "u_modelViewMat44", modelMat );
ShaderProgram.SetUniform3f( progDraw, "u_color", col[i] );
gl.drawElements( gl.TRIANGLES, bufObj.inx.len, gl.UNSIGNED_SHORT, 0 );
}
gl.disableVertexAttribArray( progDraw.pos );
var newColor = "#000000";
var colorMap = ["#ff0000", "#ffff00", "#0000ff" ];
var pos = [-1, -1];
if (mousePos[0] > 0 && mousePos[1] > 0 ) {
var pos = [2.0 * mousePos[0] / canvas.width - 1.0, 1.0 - 2.0 * mousePos[1] / canvas.height];
for ( var i = 0; i < 3; ++ i ) {
var testVec = [ pos[0], pos[1], 0 ];
testVec = Transform(testVec, matOrthoInv);
testVec = Transform(testVec, invMat[i]);
if (testVec[0] > -1.0 && testVec[0] < 1.0 && testVec[1] > -1.0 && testVec[1] < 1.0 ) {
newColor = colorMap[i];
}
}
}
document.getElementById( "color" ).value = newColor;
document.getElementById( "mouseX" ).innerHTML = pos[0];
document.getElementById( "mouseY" ).innerHTML = pos[1];
}
var startTime;
function Fract( val ) {
return val - Math.trunc( val );
}
function CalcAng( currentTime, intervall ) {
return Fract( (currentTime - startTime) / (1000*intervall) ) * 2.0 * Math.PI;
}
function CalcMove( currentTime, intervall, range ) {
var pos = self.Fract( (currentTime - startTime) / (1000*intervall) ) * 2.0
var pos = pos < 1.0 ? pos : (2.0-pos)
return range[0] + (range[1] - range[0]) * pos;
}
var mousePos = [-1, -1];
var gl;
var prog;
var bufObj = {};
function cameraStart() {
var canvas = document.getElementById( "camera-canvas");
gl = canvas.getContext( "experimental-webgl" );
if ( !gl )
return;
progDraw = ShaderProgram.Create(
[ { source : draw_vert, stage : gl.VERTEX_SHADER },
{ source : draw_frag, stage : gl.FRAGMENT_SHADER }
],
[ "u_projectionMat44", "u_modelViewMat44", "u_color"] );
progDraw.inPos = gl.getAttribLocation( progDraw, "inPos" );
if ( prog == 0 )
return;
var pos = [ -1, -1, 1, -1, 1, 1, -1, 1 ];
var inx = [ 0, 1, 2, 0, 2, 3 ];
bufObj.pos = gl.createBuffer();
gl.bindBuffer( gl.ARRAY_BUFFER, bufObj.pos );
gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( pos ), gl.STATIC_DRAW );
bufObj.inx = gl.createBuffer();
bufObj.inx.len = inx.length;
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufObj.inx );
gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( inx ), gl.STATIC_DRAW );
startTime = Date.now();
setInterval(drawScene, 50);
}
(function() {
document.onmousemove = handleMouseMove;
function handleMouseMove(event) {
var dot, eventDoc, doc, body, pageX, pageY;
event = event || window.event; // IE-ism
if (event.pageX == null && event.clientX != null) {
eventDoc = (event.target && event.target.ownerDocument) || document;
doc = eventDoc.documentElement;
body = eventDoc.body;
event.pageX = event.clientX +
(doc && doc.scrollLeft || body && body.scrollLeft || 0) -
(doc && doc.clientLeft || body && body.clientLeft || 0);
event.pageY = event.clientY +
(doc && doc.scrollTop || body && body.scrollTop || 0) -
(doc && doc.clientTop || body && body.clientTop || 0 );
}
var canvas = document.getElementById( "camera-canvas");
var x = event.pageX - canvas.offsetLeft;
var y = event.pageY - canvas.offsetTop;
mousePos = [-1, -1];
if ( x >= 0 && x < canvas.width && y >= 0 && y < canvas.height ) {
mousePos = [x, y];
}
}
})();
</script>
<body onload="cameraStart();">
<div style="margin-left: 260px;">
<div style="float: right; width: 100%; background-color: #CCF;">
<form name="inputs">
<table>
<tr> <td> <input type="color" value="#000000" id="color" disabled></td> </tr>
<tr> <td> <span id="mouseX">0</span> </td> </tr>
<tr> <td> <span id="mouseY">0</span> </td> </tr>
</table>
</form>
</div>
<div style="float: right; width: 260px; margin-left: -260px;">
<canvas id="camera-canvas" style="border: none;" width="256" height="256"></canvas>
</div>
<div style="clear: both;"></div>
</div>
</body>