How to get cursor coordinates relative to matrix scale in pyglet/opengl?

I am making a 2D game in pyglet and use both glTranslatef and glScalef:

def background_motion(dt):

    if stars.left:

        pyglet.gl.glTranslatef(stars.speed, 0, 0)

        stars.translation[0] += stars.speed

    if stars.right:

        pyglet.gl.glTranslatef(-stars.speed, 0, 0)

        stars.translation[0] -= stars.speed

    if stars.up:

        pyglet.gl.glTranslatef(0, -stars.speed, 0)

        stars.translation[1] -= stars.speed

    if stars.down:

        pyglet.gl.glTranslatef(0, stars.speed, 0)

        stars.translation[1] += stars.speed 

pyglet.clock.schedule_interval(background_motion, 0.05)



@window.event

def on_mouse_scroll(x, y, scroll_x, scroll_y):

    if scroll_y > 0:

        stars.scale += 0.01



    elif scroll_y < 0:

        stars.scale -= 0.01

@window.event

def on_draw():

    window.clear()



    pyglet.gl.glScalef(stars.scale,stars.scale, 1, 1)



    stars.image.draw()

    for s in game.ships:

        s.draw()



    pyglet.gl.glPushMatrix()

    pyglet.gl.glLoadIdentity()



    #HUD Start

    overlay.draw(stars.image.x,stars.image.y,game.ships,stars.scale,stars.image.width)

    if game.pause:

        pause_text.draw()

    #HUD End



    pyglet.gl.glPopMatrix()

    stars.scale = 1

However I also need the cursor coordinates relative to the background. For the movement I simply added the translation onto the x y coordinates which works however only when I don't scale the matrix:

@window.event

def on_mouse_motion(x, y, dx, dy):

    if player.course_setting:

        player.projected_heading = (x - stars.translation[0],y -stars.translation[1])

How can I get the cursor coordinates accounting for scale?

asked Jan 1 at 11:29

Jonas

305

First things first: You shouldn't be using the fixed function matrix stack in the first place. It's been deprecated for well over a decade.

– datenwolf
Jan 1 at 12:32

Divide player.projected_heading by stars.scale

– Rabbid76
Jan 1 at 14:25

add a comment |

I am making a 2D game in pyglet and use both glTranslatef and glScalef:

def background_motion(dt):

    if stars.left:

        pyglet.gl.glTranslatef(stars.speed, 0, 0)

        stars.translation[0] += stars.speed

    if stars.right:

        pyglet.gl.glTranslatef(-stars.speed, 0, 0)

        stars.translation[0] -= stars.speed

    if stars.up:

        pyglet.gl.glTranslatef(0, -stars.speed, 0)

        stars.translation[1] -= stars.speed

    if stars.down:

        pyglet.gl.glTranslatef(0, stars.speed, 0)

        stars.translation[1] += stars.speed 

pyglet.clock.schedule_interval(background_motion, 0.05)



@window.event

def on_mouse_scroll(x, y, scroll_x, scroll_y):

    if scroll_y > 0:

        stars.scale += 0.01



    elif scroll_y < 0:

        stars.scale -= 0.01

@window.event

def on_draw():

    window.clear()



    pyglet.gl.glScalef(stars.scale,stars.scale, 1, 1)



    stars.image.draw()

    for s in game.ships:

        s.draw()



    pyglet.gl.glPushMatrix()

    pyglet.gl.glLoadIdentity()



    #HUD Start

    overlay.draw(stars.image.x,stars.image.y,game.ships,stars.scale,stars.image.width)

    if game.pause:

        pause_text.draw()

    #HUD End



    pyglet.gl.glPopMatrix()

    stars.scale = 1

However I also need the cursor coordinates relative to the background. For the movement I simply added the translation onto the x y coordinates which works however only when I don't scale the matrix:

@window.event

def on_mouse_motion(x, y, dx, dy):

    if player.course_setting:

        player.projected_heading = (x - stars.translation[0],y -stars.translation[1])

How can I get the cursor coordinates accounting for scale?

asked Jan 1 at 11:29

Jonas

305

First things first: You shouldn't be using the fixed function matrix stack in the first place. It's been deprecated for well over a decade.

– datenwolf
Jan 1 at 12:32

Divide player.projected_heading by stars.scale

– Rabbid76
Jan 1 at 14:25

add a comment |

I am making a 2D game in pyglet and use both glTranslatef and glScalef:

def background_motion(dt):

    if stars.left:

        pyglet.gl.glTranslatef(stars.speed, 0, 0)

        stars.translation[0] += stars.speed

    if stars.right:

        pyglet.gl.glTranslatef(-stars.speed, 0, 0)

        stars.translation[0] -= stars.speed

    if stars.up:

        pyglet.gl.glTranslatef(0, -stars.speed, 0)

        stars.translation[1] -= stars.speed

    if stars.down:

        pyglet.gl.glTranslatef(0, stars.speed, 0)

        stars.translation[1] += stars.speed 

pyglet.clock.schedule_interval(background_motion, 0.05)



@window.event

def on_mouse_scroll(x, y, scroll_x, scroll_y):

    if scroll_y > 0:

        stars.scale += 0.01



    elif scroll_y < 0:

        stars.scale -= 0.01

@window.event

def on_draw():

    window.clear()



    pyglet.gl.glScalef(stars.scale,stars.scale, 1, 1)



    stars.image.draw()

    for s in game.ships:

        s.draw()



    pyglet.gl.glPushMatrix()

    pyglet.gl.glLoadIdentity()



    #HUD Start

    overlay.draw(stars.image.x,stars.image.y,game.ships,stars.scale,stars.image.width)

    if game.pause:

        pause_text.draw()

    #HUD End



    pyglet.gl.glPopMatrix()

    stars.scale = 1

However I also need the cursor coordinates relative to the background. For the movement I simply added the translation onto the x y coordinates which works however only when I don't scale the matrix:

@window.event

def on_mouse_motion(x, y, dx, dy):

    if player.course_setting:

        player.projected_heading = (x - stars.translation[0],y -stars.translation[1])

How can I get the cursor coordinates accounting for scale?

asked Jan 1 at 11:29

Jonas

305

I am making a 2D game in pyglet and use both glTranslatef and glScalef:

def background_motion(dt):

    if stars.left:

        pyglet.gl.glTranslatef(stars.speed, 0, 0)

        stars.translation[0] += stars.speed

    if stars.right:

        pyglet.gl.glTranslatef(-stars.speed, 0, 0)

        stars.translation[0] -= stars.speed

    if stars.up:

        pyglet.gl.glTranslatef(0, -stars.speed, 0)

        stars.translation[1] -= stars.speed

    if stars.down:

        pyglet.gl.glTranslatef(0, stars.speed, 0)

        stars.translation[1] += stars.speed 

pyglet.clock.schedule_interval(background_motion, 0.05)



@window.event

def on_mouse_scroll(x, y, scroll_x, scroll_y):

    if scroll_y > 0:

        stars.scale += 0.01



    elif scroll_y < 0:

        stars.scale -= 0.01

@window.event

def on_draw():

    window.clear()



    pyglet.gl.glScalef(stars.scale,stars.scale, 1, 1)



    stars.image.draw()

    for s in game.ships:

        s.draw()



    pyglet.gl.glPushMatrix()

    pyglet.gl.glLoadIdentity()



    #HUD Start

    overlay.draw(stars.image.x,stars.image.y,game.ships,stars.scale,stars.image.width)

    if game.pause:

        pause_text.draw()

    #HUD End



    pyglet.gl.glPopMatrix()

    stars.scale = 1

However I also need the cursor coordinates relative to the background. For the movement I simply added the translation onto the x y coordinates which works however only when I don't scale the matrix:

@window.event

def on_mouse_motion(x, y, dx, dy):

    if player.course_setting:

        player.projected_heading = (x - stars.translation[0],y -stars.translation[1])

How can I get the cursor coordinates accounting for scale?

python-3.x opengl pyglet

asked Jan 1 at 11:29

Jonas

305

asked Jan 1 at 11:29

Jonas

305

asked Jan 1 at 11:29

Jonas

305

asked Jan 1 at 11:29

Jonas

305

asked Jan 1 at 11:29

Jonas

305

First things first: You shouldn't be using the fixed function matrix stack in the first place. It's been deprecated for well over a decade.

– datenwolf
Jan 1 at 12:32

Divide player.projected_heading by stars.scale

– Rabbid76
Jan 1 at 14:25

add a comment |

First things first: You shouldn't be using the fixed function matrix stack in the first place. It's been deprecated for well over a decade.

– datenwolf
Jan 1 at 12:32

Divide player.projected_heading by stars.scale

– Rabbid76
Jan 1 at 14:25

First things first: You shouldn't be using the fixed function matrix stack in the first place. It's been deprecated for well over a decade.

– datenwolf
Jan 1 at 12:32

Divide player.projected_heading by stars.scale

– Rabbid76
Jan 1 at 14:25

add a comment |

1 Answer
1

active

oldest

votes

You'll have to unproject the pointer position. Projection happens as following:

p_eye = M · p

p_clip = P · p_eye

at this point the primitive is clipped, but we can ignore this for the moment. After clipping comes the homogenous divide, which brings the coordinates into NDC space, i.e. the viewport is treated as a cuboid of dimensions [-1,1]×[-1,1]×[0,1]

p_NDC = p_clip / p_clip.w

From there it's mapped into pixel dimensions. I'm going to omit this step here.

Unprojecting is doing these operations in reverse. There's a small trick in there, regarding the homogenous divide, though; this is kind of an "antisymmetric" (not the proper term for this, but it gets across the point) operation, and happens at the end, for each projection and unprojection. Unprojection hence is

p_NDC.w = 1

p_eye' = inv(P)·p_NDC

p' = inv(M)·p_eye'

p = p' / p'.w

All of this has been wrapped into unproject functions for your convenience by GLU (if you insist on using the fixed function matrix stack) or GLM – but not my linmath.h, though.

answered Jan 1 at 13:03

datenwolf

133k10135238

Okay I tried using opengls unproject function like this: pyglet.gl.gluUnProject(x,y,0,pyglet.gl.GL_MODELVIEW_MATRIX,pyglet.gl.GL_PROJECTION_MATRIX,pyglet.gl.glViewport,0,0,0) But that gave me the error: ctypes.ArgumentError: argument 4: <class 'TypeError'>: expected LP_c_double instance instead of int What am I doing wrong?'

– Jonas
Jan 1 at 20:50

@Rabbid76 Okay now I get this error TypeError: this function takes at least 2 arguments (1 given) from this line model_view = np.array(pyglet.gl.glGetDoublev(pyglet.gl.GL_MODELVIEW_MATRIX))

– Jonas
Jan 2 at 7:24

add a comment |

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1 Answer
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active

oldest

votes

1 Answer
1

active

oldest

votes

You'll have to unproject the pointer position. Projection happens as following:

p_eye = M · p

p_clip = P · p_eye

p_NDC = p_clip / p_clip.w

From there it's mapped into pixel dimensions. I'm going to omit this step here.

p_NDC.w = 1

p_eye' = inv(P)·p_NDC

p' = inv(M)·p_eye'

p = p' / p'.w

All of this has been wrapped into unproject functions for your convenience by GLU (if you insist on using the fixed function matrix stack) or GLM – but not my linmath.h, though.

answered Jan 1 at 13:03

datenwolf

133k10135238

Okay I tried using opengls unproject function like this: pyglet.gl.gluUnProject(x,y,0,pyglet.gl.GL_MODELVIEW_MATRIX,pyglet.gl.GL_PROJECTION_MATRIX,pyglet.gl.glViewport,0,0,0) But that gave me the error: ctypes.ArgumentError: argument 4: <class 'TypeError'>: expected LP_c_double instance instead of int What am I doing wrong?'

– Jonas
Jan 1 at 20:50

@Rabbid76 Okay now I get this error TypeError: this function takes at least 2 arguments (1 given) from this line model_view = np.array(pyglet.gl.glGetDoublev(pyglet.gl.GL_MODELVIEW_MATRIX))

– Jonas
Jan 2 at 7:24

add a comment |

You'll have to unproject the pointer position. Projection happens as following:

p_eye = M · p

p_clip = P · p_eye

p_NDC = p_clip / p_clip.w

From there it's mapped into pixel dimensions. I'm going to omit this step here.

p_NDC.w = 1

p_eye' = inv(P)·p_NDC

p' = inv(M)·p_eye'

p = p' / p'.w

All of this has been wrapped into unproject functions for your convenience by GLU (if you insist on using the fixed function matrix stack) or GLM – but not my linmath.h, though.

answered Jan 1 at 13:03

datenwolf

133k10135238

Okay I tried using opengls unproject function like this: pyglet.gl.gluUnProject(x,y,0,pyglet.gl.GL_MODELVIEW_MATRIX,pyglet.gl.GL_PROJECTION_MATRIX,pyglet.gl.glViewport,0,0,0) But that gave me the error: ctypes.ArgumentError: argument 4: <class 'TypeError'>: expected LP_c_double instance instead of int What am I doing wrong?'

– Jonas
Jan 1 at 20:50

@Rabbid76 Okay now I get this error TypeError: this function takes at least 2 arguments (1 given) from this line model_view = np.array(pyglet.gl.glGetDoublev(pyglet.gl.GL_MODELVIEW_MATRIX))

– Jonas
Jan 2 at 7:24

add a comment |

You'll have to unproject the pointer position. Projection happens as following:

p_eye = M · p

p_clip = P · p_eye

p_NDC = p_clip / p_clip.w

From there it's mapped into pixel dimensions. I'm going to omit this step here.

p_NDC.w = 1

p_eye' = inv(P)·p_NDC

p' = inv(M)·p_eye'

p = p' / p'.w

All of this has been wrapped into unproject functions for your convenience by GLU (if you insist on using the fixed function matrix stack) or GLM – but not my linmath.h, though.

answered Jan 1 at 13:03

datenwolf

133k10135238

You'll have to unproject the pointer position. Projection happens as following:

p_eye = M · p

p_clip = P · p_eye

p_NDC = p_clip / p_clip.w

From there it's mapped into pixel dimensions. I'm going to omit this step here.

p_NDC.w = 1

p_eye' = inv(P)·p_NDC

p' = inv(M)·p_eye'

p = p' / p'.w

All of this has been wrapped into unproject functions for your convenience by GLU (if you insist on using the fixed function matrix stack) or GLM – but not my linmath.h, though.

answered Jan 1 at 13:03

datenwolf

133k10135238

answered Jan 1 at 13:03

datenwolf

133k10135238

answered Jan 1 at 13:03

datenwolf

133k10135238

answered Jan 1 at 13:03

datenwolf

133k10135238

Okay I tried using opengls unproject function like this: pyglet.gl.gluUnProject(x,y,0,pyglet.gl.GL_MODELVIEW_MATRIX,pyglet.gl.GL_PROJECTION_MATRIX,pyglet.gl.glViewport,0,0,0) But that gave me the error: ctypes.ArgumentError: argument 4: <class 'TypeError'>: expected LP_c_double instance instead of int What am I doing wrong?'

– Jonas
Jan 1 at 20:50

@Rabbid76 Okay now I get this error TypeError: this function takes at least 2 arguments (1 given) from this line model_view = np.array(pyglet.gl.glGetDoublev(pyglet.gl.GL_MODELVIEW_MATRIX))

– Jonas
Jan 2 at 7:24

add a comment |

Okay I tried using opengls unproject function like this: pyglet.gl.gluUnProject(x,y,0,pyglet.gl.GL_MODELVIEW_MATRIX,pyglet.gl.GL_PROJECTION_MATRIX,pyglet.gl.glViewport,0,0,0) But that gave me the error: ctypes.ArgumentError: argument 4: <class 'TypeError'>: expected LP_c_double instance instead of int What am I doing wrong?'

– Jonas
Jan 1 at 20:50

@Rabbid76 Okay now I get this error TypeError: this function takes at least 2 arguments (1 given) from this line model_view = np.array(pyglet.gl.glGetDoublev(pyglet.gl.GL_MODELVIEW_MATRIX))

– Jonas
Jan 2 at 7:24

Okay I tried using opengls unproject function like this: pyglet.gl.gluUnProject(x,y,0,pyglet.gl.GL_MODELVIEW_MATRIX,pyglet.gl.GL_PROJECTION_MATRIX,pyglet.gl.glViewport,0,0,0) But that gave me the error: ctypes.ArgumentError: argument 4: <class 'TypeError'>: expected LP_c_double instance instead of int What am I doing wrong?'

– Jonas
Jan 1 at 20:50

@Rabbid76 Okay now I get this error TypeError: this function takes at least 2 arguments (1 given) from this line model_view = np.array(pyglet.gl.glGetDoublev(pyglet.gl.GL_MODELVIEW_MATRIX))

– Jonas
Jan 2 at 7:24

add a comment |

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