Pyxel's text(x, y, string, color) function silently fails to print text to the screen. about pyxel

[yeputons]

Dirty hack that worked on my machine, see shaders.py:327:

-#define texture_color(index) int(texture2D(u_texture[index], uv).r * 255.0)
+#define texture_color(index) int(texture2D(u_texture[index], uv).r * 255.0 + 0.5)

My assumption is that the problem is that texture values are floats between 0.0 and 1.0, and we want to distinguish 1/255ths. Unfortunately, 1/255 cannot be represented exactly and it turns out that 1/255 * 255 (via OpenGL) is rounded down to 0 on my machine. This effect can be also noted when rendering images with blt. Say, color 1 becomes 0, 2 becomes 1, 4 becomes 3. So, instead of rounding down with int(), I now round to the approx. closest integer.

I'm not exactly sure what causes that effect or even what are exact values returned by texture2D() * 255.0 instead of 1.0. I think it should be something like 0.9999, but I haven't checked and recommend further investigation (a hotfix may be landed in the meantime).

cc @olgalupuleac

[kitao]

@yeputons I imported your modification in v0.7.8. I hope it works in your environment.

[kev-inn]

Just checked it on my system and it works for me, which is strange.

• Win10
• Python 3.6.2
• pyxel 0.7.4

Code is the same:

import pyxel

pyxel.init(160, 120)

def update():
    if pyxel.btnp(pyxel.KEY_Q):
        pyxel.quit()

def draw():
    pyxel.cls(0)
    pyxel.rect(10, 10, 20, 20, 11)
    pyxel.text(10, 10, "This is a sentence.", 11)

pyxel.run(update, draw)

[kitao]

@mattjquinn Hi, what will happen when the example #3 (draw api sample) runs on your environment?

[mattjquinn]

Example #3 also has missing text. It also appears that clip() doesn't work either, though the screen changes colors and one of the sprites moves as expected:

Example #1 is also missing the top line of text as well:

[matju]

I have a similar issue - except I'm on MacOS Sierra. brew and pip3 installed everything OK.

In my case:

• Example 1 doesn't render any text
• Clipping doesn't work for Example 3
• Some fragments of text are rendered for Example 3 (see screenshot)
• Example 3's circles don't render properly

[timbledum]

Fine on my mac at home, but getting no text displayed on my windows 10 work computer. No install issues. Tried on 3.6 and 3.7, including fresh environment.

Do we have opengl version issues perhaps? I'm finding it hard to figure out what version is installed on windows though.

[matju]

In my case I'm running MacOS 10.12.6 on a MacBook Pro (13-inch, 2016, Four Thunderbolt 3 ports) with Intel Iris Graphics 550 - apparently this supports OpenGL 4.1.

brew list --versions reports python 3.7.0 and glfw 3.2.1.

pip3 list reports:

Package     Version
----------- -------
cffi        1.11.5 
glfw        1.7.0  
numpy       1.15.0 
Pillow      5.2.0  
pip         18.0   
pycparser   2.18   
PyOpenGL    3.1.0  
pyxel       0.7.6  
setuptools  40.0.0 
sounddevice 0.3.11 
wheel       0.31.1 

[kitao]

@matju Appearently, you environment has enough specs to run Pyxel.

Now I'm wondering there is some informal OpenGL code and it causes this bug.

Could you try change line 139 of the example #3 from pyxel.blt(x, y, 0, 0, 0, 16, 16) to pyxel.blt(x, y, 4, 0, 0, 16, 16)?

By this change, Pyxel draws the system font texture with blt command.
If some characters with blue color are shown, it means the system font texture is available and the shader for text has some problem. If not, the system font texture has some problem.

[mattjquinn]

@kitao Using OpenGL 4.2, I made the change to line 139; only difference was the first cat being replaced by a black square:

Output of glxinfo is

OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile 
OpenGL core profile version string: 4.2 (Core Profile) Mesa 17.3.6
OpenGL core profile shading language version string: 4.20
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 17.3.6
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.0 Mesa 17.3.6
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00
OpenGL ES profile extensions:

Is there any advice you can give us for debugging issues with system font resources that Pyxel expects to be present?

[kitao]

@mattjquinn Thank you! It seems that the image bank #5 of Pyxel is not available.
Potential possibility is your environment doesn't allow to use five textures at the same time, or shader setting of Pyxel for textures is informal OpenGL code.

If possible, could you change line.40 of constants.py of Pyxel from `RENDERER_IMAGE_COUNT = 5' to 'RENDERER_IMAGE_COUNT = 2'?

If the example #3 works by this change, the cause is the number of the texture unit.

[mattjquinn]

No luck @kitao; after decreasing from 5 to 2, the only difference is that the background behind the first cat is gray:

So you're saying that since this doesn't work, I should look into environment limitations on using five textures at the same time?

[kitao]

@mattjquinn Sorry! You also need to the example #3.

Now, the System Font image number is 1, so please change the same line of the example #3 to pyxel.blt(x, y, 1, 0, 0, 16, 16).

[mattjquinn]

Still no luck: first cat is now completely blacked out:

[matju]

@kitao If I change line 139 of example 3 to pyxel.blt(x, y, 4, 0, 0, 16, 16) then the first cat is replaced with some faint blue text:

[kitao]

@matju Thank you for checking. This is the image I expected. So in your case, the number of the texture or size may be the cause. (Though I don't know it can cause breaking text rendering like this.)

Could you try to just change the `RENDERER_IMAGE_COUNT' of constant.py to some number less than 5 to make sure the number of the texture cause this?

[kitao]

Hi, @yeputons
Thank you for good information! I understood what happen in your environment.
So in your environment, all color drawn with blt and text command changes rather than text is not drawn?

[yeputons]

@kitao Color drawn with blt changes, yes, but text is not drawn at all: font is passed through a texture with 0/1 values, and 1 gets rounded down to 0 in texture_color, so the shader assumes that all pixels are zero and does not draw anything.

[timbledum]

This fixed it for me!

[kitao]

Good!

[mattjquinn]

Yes fixed for me as well.

[matju]

Sorry to disappoint but I have the same problem in Pyxel 0.7.8...

$ pip3 list
Package     Version
----------- -------
cffi        1.11.5 
glfw        1.7.0  
numpy       1.15.0 
Pillow      5.2.0  
pip         18.0   
pycparser   2.18   
PyOpenGL    3.1.0  
pyxel       0.7.8  
setuptools  40.0.0 
sounddevice 0.3.11 
wheel       0.31.1 

[kitao]

@matju In your case, texts are drawn partially and circles are not drawn. So I split your case as #45
Let me ask more information in #45