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OpenGL Orthographic viewport problems

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Code-R    136
I'm trying to use an ortho viewport with FBOs. when I don't setup the orthographic view, rendering is fine. when I try to use it, nothing is rendered. here's my opengl calls log:
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,1)
glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT)
glDisable(GL_DEPTH_TEST)
glMatrixMode(GL_PROJECTION)
glPushMatrix()
glLoadIdentity()
glOrtho(0.000000,1024.000000,0.000000,768.000000,-1.000000,1.000000)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
glColor4fv([1.000000,1.000000,1.000000,1.000000])
glTranslatef(512.000000,384.000000,0.000000)
glActiveTextureARB(GL_TEXTURE0)
glEnable(GL_TEXTURE_2D)
glEnable(GL_DEPTH_TEST)
glBindTexture(GL_TEXTURE_2D,3)
glBegin(GL_QUADS) Textures[ (0,3) ] 
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([0.000000,0.000000,0.000000])
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([0.000000,1.000000,0.000000])
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([1.000000,1.000000,0.000000])
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([1.000000,0.000000,0.000000])
glEnd()
glMatrixMode(GL_PROJECTION)
glPopMatrix()
//Frame ends here
//This part draws the FBO to a fullscreen quad. it's tested, and it works.
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,0)
glPushAttrib(GL_CURRENT_BIT | GL_POINT_BIT | GL_LINE_BIT | GL_POLYGON_BIT | GL_POLYGON_STIPPLE_BIT | GL_PIXEL_MODE_BIT | GL_LIGHTING_BIT | GL_FOG_BIT | GL_DEPTH_BUFFER_BIT | GL_ACCUM_BUFFER_BIT | GL_STENCIL_BUFFER_BIT | GL_VIEWPORT_BIT | GL_TRANSFORM_BIT | GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_HINT_BIT | GL_EVAL_BIT | GL_LIST_BIT | GL_TEXTURE_BIT | GL_SCISSOR_BIT)
glDisable(GL_DEPTH_TEST)
glMatrixMode(GL_PROJECTION)
glPushMatrix()
glLoadIdentity()
glOrtho(0.000000,1024.000000,768.000000,0.000000,-1.000000,1.000000)
glMatrixMode(GL_MODELVIEW)
glPushMatrix()
glLoadIdentity()
glActiveTexture(GL_TEXTURE0)
glEnable(GL_TEXTURE_2D)
glBindTexture(GL_TEXTURE_2D,1)
glBegin(GL_QUADS) Textures[ (0,1) ] 
glColor3f(1.000000,1.000000,1.000000)
glTexCoord2f(0.000000,0.000000)
glVertex3f(0.000000,768.000000,0.000000)
glTexCoord2f(1.000000,0.000000)
glVertex3f(1024.000000,768.000000,0.000000)
glTexCoord2f(1.000000,1.000000)
glVertex3f(1024.000000,0.000000,0.000000)
glTexCoord2f(0.000000,1.000000)
glVertex3f(0.000000,0.000000,0.000000)
glEnd()
glMatrixMode(GL_PROJECTION)
glPopMatrix()
glMatrixMode(GL_MODELVIEW)
glPopMatrix()
glPopAttrib()
wglSwapBuffers(0xd601137f)=true 

any ideas? TIA

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dawidjoubert    161
glPushAttrib(GL_CURRENT_BIT | GL_POINT_BIT | GL_LINE_BIT | GL_POLYGON_BIT | GL_POLYGON_STIPPLE_BIT | GL_PIXEL_MODE_BIT | GL_LIGHTING_BIT | GL_FOG_BIT | GL_DEPTH_BUFFER_BIT | GL_ACCUM_BUFFER_BIT | GL_STENCIL_BUFFER_BIT | *****GL_VIEWPORT_BIT***** | GL_TRANSFORM_BIT | GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_HINT_BIT | GL_EVAL_BIT | GL_LIST_BIT | GL_TEXTURE_BIT | GL_SCISSOR_BIT);

I noticed you Pushed the GL_VIEWPORT_BIT, now i dont know if it is that but try removing

glPopAttrib() --> And see if u get results!

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Code-R    136
nop, that wasn't it. besides, this part is in the part that renders the fb to a fullscreen quad, and i'm sure it works, becuase when I draw stuff in non-ortho, it shows up perfectly ok.

any ideas?

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dawidjoubert    161
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([0.000000,0.000000,0.000000])
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([0.000000,1.000000,0.000000])
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([1.000000,1.000000,0.000000])
glMultiTexCoord2fv(GL_TEXTURE0,0xb225a4)
glVertex3fv([1.000000,0.000000,0.000000])

crap im such an idiot... its right infront of me!!!!

Okay in Projection your screen looks like this


-1------------>X +1
|
|
|
|
Y+1

And thats why it works on projection compared to ur current ortho settings
which are
0------------>X +1024
|
|
|
|
Y+786


The reason is GL_VIEWPORT already set the Drawing area, all you do when you edit the projection matrix is change how the stuff get Transformed onto that area.

Try Replacing your ortho values with
glOrtho(0.000000,1.024*2,0.000000,0.768*2,-1.000000,1.000000)

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Code-R    136
nope, didn't work. I'm wondering why the part that renders the fbo to a fullscreen quad using a similar method works, but this doesn't...

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Guest Anonymous Poster   
Guest Anonymous Poster
well, I think I know what it is

glOrtho(0.000000,1024.000000,768.000000,0.000000,-1.000000,1.000000);

should be.

glOrtho(0.000000, 0.000000, 1024.000000, 768.000000,-1.000000,1.000000);

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Code-R    136
Thanks! I got it now! actually, it should be (0,1024,768,0), as I use the bottom left as the origin. Thanks again everyone, ratings++.

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