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t33mu
04-16-2001, 07:22 AM
Hello,

I'm trying to implement projective texture mapping, but can't get it quite working ok.

Here's what i'm doing atm:

static GLfloat perspectiveMatrix[16];
static GLfloat modelViewMatrix[16];

void EnableProjectiveTexturemapping(void)
{
GLfloat objPlaneS[] = { 1.0f, 0.0f, 0.0f, 0.0f };
GLfloat objPlaneT[] = { 0.0f, 1.0f, 0.0f, 0.0f };
GLfloat objPlaneR[] = { 0.0f, 0.0f, 1.0f, 0.0f };
GLfloat objPlaneQ[] = { 0.0f, 0.0f, 0.0f, 1.0f };
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
glTexGenfv(GL_S, GL_OBJECT_PLANE, objPlaneS);
glTexGenfv(GL_T, GL_OBJECT_PLANE, objPlaneT);
glTexGenfv(GL_R, GL_OBJECT_PLANE, objPlaneR);
glTexGenfv(GL_Q, GL_OBJECT_PLANE, objPlaneQ);
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);
glEnable(GL_TEXTURE_GEN_R);
glEnable(GL_TEXTURE_GEN_Q);

glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glTranslatef(0.5f, 0.5f, 0.0f);
glScalef(0.5f, 0.5f, 1.0f);
glMultMatrixf(perspectiveMatrix);
glMultMatrixf(modelViewMatrix);
}


int InitGL(GLvoid)
{

--->8---
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f);
glPushMatrix();
{
glRotatef(-15.0f, 1.0f,0.0f,0.0f);
glRotatef(0.0f, 1.0f,0.0f,0.0f);
glRotatef(-12.0f, 0.0f,1.0f,0.0f);
glGetFloatv(GL_MODELVIEW_MATRIX, modelViewMatrix);
}
glPopMatrix();
EnableProjectiveTexturemapping();
---8<---

}

and then the main drawing loop:

int DrawGLScene(GLvoid)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0f, 0.0f, -15.0f);
glRotatef(xRotate,1.0f,0.0f,0.0f);
glRotatef(yRotate,0.0f,1.0f,0.0f);
glRotatef(zRotate,0.0f,0.0f,1.0f);
glGetFloatv(GL_MODELVIEW_MATRIX, modelViewMatrix);

glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glTranslatef(0.5f, 0.5f, 0.0f);
glScalef(0.5f, 0.5f, 1.0f);
glMultMatrixf(perspectiveMatrix);
glMultMatrixf(modelViewMatrix);

glBindTexture(GL_TEXTURE_2D, texture[0]);
cube.renderClassicWithoutTexCoords();
xRotate+=xRot;
yRotate+=yRot;
zRotate+=zRot;
}


Could anyone explain me why this isn't working or how it actually SHOULD be done?

source & win32 executable can be found here: wslinux.website.fi/superdivine/projtex.zip (http://wslinux.website.fi/superdivine/projtex.zip)

I'd really appreciate if someone could explain me this projective texture mapping thingie http://www.opengl.org/discussion_boards/ubb/smile.gif

Thanks in advance,

-t33

mango
04-16-2001, 07:54 PM
I have not looked at the sources but here is a page about projective textures http://reality.sgi.com/mjk/tips/projtex/
More presentations can be found at http://www.nvidia.com/Developer.nsf

Why do you not write what the problem is?