From: Siedle, Pete (P.Siedle++at++tees.ac.uk)
Date: 05/14/2001 05:31:48
pfHi
I've got an app in which I'm looking at doing a projected light map effect.
The app is actually done in Vega, but the projected light map bit is done
using embedded performer and OpenGL!
Anyway, I've got it working, kind of!! It works on an Octane, O2 and Indy
I've tried it on; but doesn't work as expected on our deskside Onyx!
The app does it's second pass at rendering, but the lightmap isn't projected
as expected (the objects in the scene are just rendered black). So I think
that I'm not setting a state attribute (or something) which the IR2 hardware
needs to use/generate/apply the genetated uv coords for the lightmap
texture!
Anyone got any ideas as to getting it working?
Many thanks in advance
Pete
To help anyone who might be kind enough to provide some feedback, I've
included the relevent code segments below:
...snip...
doGenTexCoords();
/*app loop*/
do
{
....snip...
/* first render pass done */
/* set up for proj tex 4 sec pass */
set4TexProj();
/* second render pass */
pfDraw();
/* reset back to orig for first pass again */
resetFromTexProj();
}while(noexit);
void doGenTexCoords(void)
{
pfVec4 clr = {0.0, 0.0, 0.0, 1.0};
/* altering the active value in these can scale texture size */
GLfloat pS[] = {1.0, 0.0, 0.0, 0.0};
GLfloat pT[] = {0.0, 1.0, 0.0, 0.0};
GLfloat pR[] = {0.0, 0.0, 1.0, 0.0};
GLfloat pQ[] = {0.0, 0.0, 0.0, 1.0};
/**** Setup Tex ****/
/* set env for texture */
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
pfTexBorderType(tex, PFTEX_BORDER_COLOR);
pfTexBorderColor(tex, clr);
/* gen tex coords */
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
glTexGenfv(GL_S, GL_EYE_PLANE, pS);
glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
glTexGenfv(GL_T, GL_EYE_PLANE, pT);
glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
glTexGenfv(GL_R, GL_EYE_PLANE, pR);
glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
glTexGenfv(GL_Q, GL_EYE_PLANE, pQ);
}
void set4TexProj(float ox, ...snip... float uz)
{
GLfloat mvmat[16], imvmat[16];
glEnable(GL_BLEND);
pfEnable(PFEN_TEXTURE);
pfApplyTex(tex);
pfOverride(PFSTATE_ENTEXTURE | PFSTATE_TEXTURE, PF_ON);
/*different blend effects */
/*glBlendFunc(GL_ONE, GL_SRC_COLOR);*/
/*glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);*/
/*glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);*/
/*glBlendFunc(GL_ZERO, GL_SRC_COLOR);*/
glBlendFunc(GL_ZERO, GL_ONE_MINUS_SRC_ALPHA);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glGetFloatv(GL_MODELVIEW_MATRIX, mvmat);
invertMatrix(&imvmat[0], mvmat);
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glTranslatef(0.5, 0.5, 0.0);
glScalef(0.5, 0.5, 1.0);
/*first 4 no's in glFrustum scale the proj tex*/
glFrustum(-0.1, 0.1, -0.05, 0.05, 0.1, 1000.0);
/* val's ox - uz from func param's, give projection */
gluLookAt(ox, oy, oz, ax, ay, az, ux, uy, uz);
glMultMatrixf(imvmat);
glMatrixMode(GL_MODELVIEW);
glEnable(GL_TEXTURE_2D);
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);
glEnable(GL_TEXTURE_GEN_R);
glEnable(GL_TEXTURE_GEN_Q);
}
void resetFromTexProj(void)
{
glDisable(GL_TEXTURE_2D);
glDisable(GL_TEXTURE_GEN_S);
glDisable(GL_TEXTURE_GEN_T);
glDisable(GL_TEXTURE_GEN_R);
glDisable(GL_TEXTURE_GEN_Q);
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
pfOverride(PFSTATE_ENTEXTURE | PFSTATE_TEXTURE, PF_OFF);
pfDisable(PFEN_TEXTURE);
glBlendFunc(GL_ONE, GL_ZERO);
glDisable(GL_BLEND);
}
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