texturing a quad

BlitzMax Forums/OpenGL Module/texturing a quad

EOF	(Posted 2005) [#1]

I'm playing with opengl and trying to texture a quad although the texture does not appear.
Any ideas?

bglCreateContext (800, 600, 32, 0, BGL_BACKBUFFER | BGL_DEPTHBUFFER)
'bglSetSwapInterval(1)
InitGl()

pm:TPixmap=LoadPixmap("testimage.bmp")
Global tex=bglTexFromPixmap(pm,0)


While Not KeyHit(KEY_ESCAPE)
	mx=MouseX() ; my=-(MouseY()-454)
	glClear GL_COLOR_BUFFER_BIT '| GL_DEPTH_BUFFER_BIT
	glLoadIdentity
	'glColor3f 1.0,0.5,1.0
	glEnable GL_TEXTURE_2D
	glBindTexture GL_TEXTURE_2D,tex
	' quad
	glBegin GL_QUADS
	 glTexCoord2f 0.0, 0.0
	 glVertex2f mx , my
	 glTexCoord2f 1.0, 0.0
	 glVertex2f mx+120 , my
	 glTexCoord2f 1.0, 1.0
	 glVertex2f mx+120 , my+120
	 glTexCoord2f 0.0, 1.0
	 glVertex2f mx , my+120
	glEnd
	FlushMem
	'SetColor 50,50,50
	'DrawRect mx,MouseY(),120,120
	bglSwapBuffers
Wend

End

Function InitGl()
	'glShadeModel(GL_SMOOTH)
	glClearColor(0.4, 0.6, 0.7, 0.5)
	'glClearDepth(1.0)
	'glEnable(GL_DEPTH_TEST)
	'glDepthFunc(GL_LEQUAL)
	'glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST)
	glViewport(0,0,800,600)
	glMatrixMode(GL_PROJECTION)
	glLoadIdentity()
	gluortho2d(0.0, 800, 0.0, 600)
	glMatrixMode(GL_MODELVIEW)
	glLoadIdentity()
End Function

Also, is there a method for converting 2d vertex coordinates to 2d screen pixel coordinates?

Chris C

(Posted 2005) [#2]

only works in full screen 'cause of an 'undocumented feature'
>;p

Global tex

bglCreateContext (800, 600, 32, 0, bgl_fullscreen|BGL_BACKBUFFER | BGL_DEPTHBUFFER)
'bglSetSwapInterval(1)
InitGl()

While Not KeyHit(KEY_ESCAPE)
	mx=MouseX()-64 ; my=600-MouseY()-64
	glClear GL_COLOR_BUFFER_BIT '| GL_DEPTH_BUFFER_BIT
	glLoadIdentity
	glColor3f 1.0,0.5,1.0
	glEnable GL_TEXTURE_2D
	glBindTexture GL_TEXTURE_2D,tex
	' quad
	glBegin GL_QUADS
	 glTexCoord2f 0.0, 0.0
	 glVertex2f mx , my
	 glTexCoord2f 1.0, 0.0
	 glVertex2f mx+120 , my
	 glTexCoord2f 1.0, 1.0
	 glVertex2f mx+120 , my+120
	 glTexCoord2f 0.0, 1.0
	 glVertex2f mx , my+120
	glEnd
	FlushMem

	bglSwapBuffers
Wend

End

Function InitGl()
	glShadeModel(GL_SMOOTH)
	glClearColor(0.4, 0.6, 0.7, 0.5)
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST)
	glViewport(0,0,800,600)
	glMatrixMode(GL_PROJECTION)
	glLoadIdentity()
	gluortho2d(0.0, 800, 0.0, 600)
	glMatrixMode(GL_MODELVIEW)
	glLoadIdentity()
	tex=bglTexFromPixmap(LoadPixmap("metal.bmp"))
	glTexParameteri GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR
	glTexParameteri GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST
End Function

EOF	(Posted 2005) [#3]

Hi Chris,

I got it working in windowed and fullscreen modes (Win32Beta) but the image looks terrible.
Any ideas on how to display pixel-perfect quads?

Graphics 800,600,0

Global w,h
Global tex=LoadTexture("testimage.bmp")

glTexParameteri GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR
glTexParameteri GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR
glLoadIdentity
glEnable GL_TEXTURE_2D

While Not KeyHit(KEY_ESCAPE)
	mx=MouseX() ; my=MouseY()
	Cls
	glLoadIdentity
	glBindTexture GL_TEXTURE_2D,tex
	' quad
	glBegin GL_QUADS
	 glTexCoord2f 0.0, 0.0 ; glVertex2f mx , my
	 glTexCoord2f 1.0, 0.0 ; glVertex2f mx+w , my
	 glTexCoord2f 1.0, 1.0 ; glVertex2f mx+w , my+h
	 glTexCoord2f 0.0, 1.0 ; glVertex2f mx , my+h
	glEnd
	FlushMem
	Flip
	Delay 10
Wend

End

Function LoadTexture(f$)
	Local pm:TPixmap=LoadPixmap(f$)
	w=pm.width ; h=pm.height
	Local texname=bglTexFromPixmap(pm)
	Return texname
End Function

Chris C

(Posted 2005) [#4]

re quads see above... pixel perfect and coloured, if
you look at the code, there are errors in your
attempt [edit] oh so thats wht u meant by pixel
perfect! least you got an answer...

Theres a bug in max at the mo re: mouse pointers and
windowed mode...