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https://github.com/QB64-Phoenix-Edition/QB64pe.git
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147 lines
5.5 KiB
QBasic
147 lines
5.5 KiB
QBasic
CHDIR "programs\samples\open_gl"
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DIM SHARED AllowSubGL 'we'll set this after we finish our setup immediately below, just in case
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'there is anything here (there isn't currently though) that SUB _GL will depend on
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TYPE DONT_USE_GLH_Handle_TYPE
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in_use AS _BYTE
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handle AS LONG
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END TYPE
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REDIM SHARED DONT_USE_GLH_Handle(1000) AS DONT_USE_GLH_Handle_TYPE
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SCREEN _NEWIMAGE(1024, 768, 32)
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backdrop = _LOADIMAGE("xcom_backdrop.jpg")
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_PUTIMAGE , backdrop
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_FREEIMAGE backdrop
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_DONTBLEND
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LINE (200, 200)-(500, 500), _RGBA(0, 255, 255, 0), BF 'create a see-through window (press 1)
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_BLEND
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AllowSubGL = 1
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DO
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'This is our program's main loop
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_LIMIT 100
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LOCATE 1, 1
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c = c + 1: PRINT "Mainloop has done nothing"; c; "times"
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PRINT "Press 1[GL behind], 2[GL on top] or 3[GL only, good for speed] to switch rendering order."
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k$ = INKEY$
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IF k$ = "1" THEN _GLRENDER _BEHIND
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IF k$ = "2" THEN _GLRENDER _ONTOP
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IF k$ = "3" THEN _GLRENDER _ONLY
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LOOP UNTIL k$ = CHR$(27)
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END
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'this specially named sub "_GL" is detected by QB64 and adds support for OpenGL commands
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'it is called automatically whenever the underlying software deems an update is possible
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'usually/ideally, this is in sync with your monitor's refresh rate
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SUB _GL STATIC
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'STATIC was used above to make all variables in this sub maintain their values between calls to this sub
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IF AllowSubGL = 0 THEN EXIT SUB 'we aren't ready yet!
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'timing is everything, we don't know how fast the 3D renderer will call this sub to we use timers to smooth things out
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T# = TIMER(0.001)
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IF ETT# = 0 THEN ETT# = T#
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ET# = T# - ETT#
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ETT# = T#
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IF sub_gl_called = 0 THEN
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sub_gl_called = 1 'we only need to perform the following code once
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i = _LOADIMAGE("xcom256.png", 32)
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mytex = GLH_Image_to_Texture(i) 'this helper function converts the image to a texture
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_FREEIMAGE i
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END IF
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'These settings affect how OpenGL will render our content
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'!!! THESE SETTINGS ARE TO SHOW HOW ALPHA CAN WORK, BUT IT IS 10x FASTER WHEN ALPHA OPTIONS ARE DISABLED !!!
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'*** every setting must be reset because SUB _GL cannot guarantee settings have not changed since last time ***
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_glMatrixMode _GL_PROJECTION 'Select The Projection Matrix
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_glLoadIdentity 'Reset The Projection Matrix
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_gluPerspective 45, _WIDTH(0) / _HEIGHT(0), 1, 100 'QB64 internally supports this GLU command for convenience sake, but does not support GLU
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_glEnable _GL_TEXTURE_2D
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_glEnable _GL_BLEND
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_glBlendFunc _GL_SRC_ALPHA, _GL_ONE_MINUS_SRC_ALPHA 'how alpha values are interpretted
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_glEnable _GL_DEPTH_TEST 'use the zbuffer
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_glDepthMask _GL_TRUE
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_glAlphaFunc _GL_GREATER, 0.5 'dont do anything if alpha isn't greater than 0.5 (or 128)
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_glEnable _GL_ALPHA_TEST
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_glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MAG_FILTER, _GL_LINEAR
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_glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MIN_FILTER, _GL_LINEAR
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'**************************************************************************************************************
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GLH_Select_Texture mytex
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_glMatrixMode _GL_MODELVIEW 'Select The Modelview Matrix
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_glLoadIdentity 'Reset The Modelview Matrix
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_glTranslatef 0, 0, -10 'Translate Into The Screen
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_glRotatef rotation1, 0, 1, 0 'spin, spin, spin...
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_glRotatef rotation2, 1, 0, 0
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_glBegin _GL_QUADS 'we will be drawing rectangles aka. QUADs
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_glTexCoord2f 0, 0: _glVertex3f 0, 0, 4 'the texture position and the position in 3D space of a vertex
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_glTexCoord2f 1, 0: _glVertex3f 5, 0, 4
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_glTexCoord2f 1, 1: _glVertex3f 5, -5, 4
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_glTexCoord2f 0, 1: _glVertex3f 0, -5, 4
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_glEnd
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RANDOMIZE USING 1 'generate the same set of random numbers each time
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_glBegin _GL_TRIANGLES 'the png (almost) only consumes a triangular region of its rectangle
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FOR t = 1 TO 10
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_glTexCoord2f 0, 0: _glVertex3f RND * 6 - 3, RND * 6 - 3, RND * 6 - 3
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_glTexCoord2f 1, 0: _glVertex3f RND * 6 - 3, RND * 6 - 3, RND * 6 - 3
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_glTexCoord2f 0.5, 1: _glVertex3f RND * 6 - 3, RND * 6 - 3, RND * 6 - 3
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NEXT
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_glEnd
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rotation1 = rotation1 + 100 * ET#
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rotation2 = rotation2 + 200 * ET#
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END SUB
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'QB64 OPEN-GL HELPER MACROS (aka. GLH macros)
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SUB GLH_Select_Texture (texture_handle AS LONG) 'turn an image handle into a texture handle
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IF texture_handle < 1 OR texture_handle > UBOUND(DONT_USE_GLH_HANDLE) THEN ERROR 258: EXIT FUNCTION
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IF DONT_USE_GLH_Handle(texture_handle).in_use = 0 THEN ERROR 258: EXIT FUNCTION
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_glBindTexture _GL_TEXTURE_2D, DONT_USE_GLH_Handle(texture_handle).handle
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END SUB
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FUNCTION GLH_Image_to_Texture (image_handle AS LONG) 'turn an image handle into a texture handle
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IF image_handle >= 0 THEN ERROR 258: EXIT FUNCTION 'don't allow screen pages
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DIM m AS _MEM
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m = _MEMIMAGE(image_handle)
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DIM h AS LONG
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h = DONT_USE_GLH_New_Texture_Handle
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GLH_Image_to_Texture = h
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_glBindTexture _GL_TEXTURE_2D, DONT_USE_GLH_Handle(h).handle
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_glTexImage2D _GL_TEXTURE_2D, 0, _GL_RGBA, _WIDTH(image_handle), _HEIGHT(image_handle), 0, &H80E1&&, _GL_UNSIGNED_BYTE, m.OFFSET
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_MEMFREE m
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END FUNCTION
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FUNCTION DONT_USE_GLH_New_Texture_Handle
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handle&& = 0
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_glGenTextures 1, _OFFSET(handle&&)
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DONT_USE_GLH_New_Texture_Handle = handle&&
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FOR h = 1 TO UBOUND(DONT_USE_GLH_Handle)
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IF DONT_USE_GLH_Handle(h).in_use = 0 THEN
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DONT_USE_GLH_Handle(h).in_use = 1
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DONT_USE_GLH_Handle(h).handle = handle&&
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DONT_USE_GLH_New_Texture_Handle = h
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EXIT FUNCTION
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END IF
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NEXT
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REDIM _PRESERVE DONT_USE_GLH_Handle(UBOUND(DONT_USE_GLH_HANDLE) * 2) AS DONT_USE_GLH_Handle_TYPE
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DONT_USE_GLH_Handle(h).in_use = 1
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DONT_USE_GLH_Handle(h).handle = handle&&
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DONT_USE_GLH_New_Texture_Handle = h
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END FUNCTION
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