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Project a Texture

Started by dasan11 Jun 3, 2006 at 9:27 AM 3 replies 1k views

Original Post

Jun 3, 2006 at 9:27 AM

I use this method to project the texture.But the result wasn't right.where is wrong? glBindTexture(GL_TEXTURE_2D, texture[0]);//define the texture glTexGenfv( GL_S, GL_EYE_LINEAR, &Splane[0] );//{1.f, 0.f, 0.f, 0.f}; glTexGenfv( GL_T, GL_EYE_LINEAR, &Tplane[0] );// {0.f, 1.f, 0.f, 0.f}; glTexGenfv( GL_R, GL_EYE_LINEAR, &Rplane[0] );// {0.f, 0.f, 1.f, 0.f}; glTexGenfv( GL_Q, GL_EYE_LINEAR, &Qplane[0] );// {0.f, 0.f, 0.f, 1.f}; glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glPushMatrix(); glMatrixMode(GL_TEXTURE); glTranslatef( 0.5, 0.5, 0.0 ); glScalef( 0.5, 0.5, 1.0 ); gluPerspective(45,1,0.1,100); gluLookAt(-40,2,30,0,0,0,0,1,0); glPopMatrix(); glMatrixMode(GL_MODELVIEW); gluLookAt(0,0,30,0,0,0,0,1,0); glBegin(GL_QUADS); glVertex3f(-10,-10,-10); glVertex3f(10,-10,-10); glVertex3f(10,10,-10); glVertex3f(-10,10,-10); glEnd();

Eitsch

Jun 3, 2006 at 10:05 AM

use something like this for all coords

glTexGenfv(GL_S,GL_EYE_PLANE,x);
glTexGeni(GL_S,GL_TEXTURE_GEN_MODE,GL_LINEAR);
glEnable(GL_TEXTURE_GEN_S);

dont forget to load identity to texture matrix otherwise your texturematrix will be updated every frame. (glPushMatrix will push the CURRENT MATRIX...so you first have to choose your matrix and then use glPushMatrix)

dasan11

Author

dasan11

Jun 3, 2006 at 9:52 PM

at last step,I need to invert the texture matrix.
use glMultMatrixf((GLfloat*)M_Inverse),
but I don't know how to get M_Inverse.
where can I find the M_Inverse value?

and I use the function to do this,but the result is wrong.

glGetFloatv( GL_TEXTURE_MATRIX, tmpMatrix ); //get the texture matrix
transposeMatrix( tmpMatrix ); //invert the matrix

glTexGenfv( GL_S, GL_OBJECT_PLANE, &tmpMatrix[0] );
glTexGenfv( GL_T, GL_OBJECT_PLANE, &tmpMatrix[4] );
glTexGenfv( GL_R, GL_OBJECT_PLANE, &tmpMatrix[8] );
glTexGenfv( GL_Q, GL_OBJECT_PLANE, &tmpMatrix[12] );

Basiror

140

Basiror

Jun 4, 2006 at 4:48 AM

You matrix has to be orthogonal in order to get the inverse of it by simply transposing the original matrix.

dasan11

Author

dasan11

Jun 4, 2006 at 5:29 AM

Quote:
Original post by Basiror
You matrix has to be orthogonal in order to get the inverse of it by simply transposing the original matrix.

the function transposeMatrix()inverses the matrix.
void transposeMatrix( GLfloat m[16] )
{
GLfloat tmp;
#define Swap( a, b ) tmp = a; a = b; b = tmp
Swap( m[1], m[4] );
Swap( m[2], m[8] );
Swap( m[3], m[12] );
Swap( m[6], m[9] );
Swap( m[7], m[13] );
Swap( m[11], m[14] );
#undef Swap
}

glGetFloatv( GL_TEXTURE_MATRIX, tmpMatrix ); //get the texture matrix
transposeMatrix( tmpMatrix ); //inverse the texture matrix
glLoadMatrixf(tmpMatrix);

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