[Question] How do I create a context

[Elsarques]

I'm trying to run an example OpenGL Project, by porting it to OpenGL ES 2, so that I can run on Termux:GUI and learn how to make 3D graphics, and i'm stuck in this problem that I can't figure out the variable that indicates the display to create a context, basically, I need help, here's the code:

import termuxgui as tg
from OpenGL.GLES2 import *  # pylint: disable=W0614
from OpenGL.GLU import *  # pylint: disable=W0614
from OpenGL.GLUT import *
import glm
from OpenGL.EGL import *

from utils.shaderLoader import Shader

with tg.Connection() as c:
  
  a = tg.Activity(c)
  
  #hdc=a
  #hglrc=eglCreateContext(hdc, None, EGL_NO_CONTEXT, None)
  #eglMakeCurrent(hdc,hglrc)
  
  g_vertex_buffer_data = [
		  -1.0,-1.0,-1.0,
		  -1.0,-1.0, 1.0,
		  -1.0, 1.0, 1.0,
		  1.0, 1.0,-1.0,
		  -1.0,-1.0,-1.0,
		  -1.0, 1.0,-1.0,
		  1.0,-1.0, 1.0,
		  -1.0,-1.0,-1.0,
		  1.0,-1.0,-1.0,
		  1.0, 1.0,-1.0,
		  1.0,-1.0,-1.0,
		  -1.0,-1.0,-1.0,
		  -1.0,-1.0,-1.0,
		  -1.0, 1.0, 1.0,
		  -1.0, 1.0,-1.0,
		  1.0,-1.0, 1.0,
		  -1.0,-1.0, 1.0,
		  -1.0,-1.0,-1.0,
		  -1.0, 1.0, 1.0,
		  -1.0,-1.0, 1.0,
		  1.0,-1.0, 1.0,
		  1.0, 1.0, 1.0,
		  1.0,-1.0,-1.0,
		  1.0, 1.0,-1.0,
		  1.0,-1.0,-1.0,
		  1.0, 1.0, 1.0,
		  1.0,-1.0, 1.0,
		  1.0, 1.0, 1.0,
		  1.0, 1.0,-1.0,
		  -1.0, 1.0,-1.0,
		  1.0, 1.0, 1.0,
		  -1.0, 1.0,-1.0,
		  -1.0, 1.0, 1.0,
		  1.0, 1.0, 1.0,
		  -1.0, 1.0, 1.0,
		  1.0,-1.0, 1.0]
  g_color_buffer_data = [ 
		0.583,  0.771,  0.014,
		0.609,  0.115,  0.436,
		0.327,  0.483,  0.844,
		0.822,  0.569,  0.201,
		0.435,  0.602,  0.223,
		0.310,  0.747,  0.185,
		0.597,  0.770,  0.761,
		0.559,  0.436,  0.730,
		0.359,  0.583,  0.152,
		0.483,  0.596,  0.789,
		0.559,  0.861,  0.639,
		0.195,  0.548,  0.859,
		0.014,  0.184,  0.576,
		0.771,  0.328,  0.970,
		0.406,  0.615,  0.116,
		0.676,  0.977,  0.133,
		0.971,  0.572,  0.833,
		0.140,  0.616,  0.489,
		0.997,  0.513,  0.064,
		0.945,  0.719,  0.592,
		0.543,  0.021,  0.978,
		0.279,  0.317,  0.505,
		0.167,  0.620,  0.077,
		0.347,  0.857,  0.137,
		0.055,  0.953,  0.042,
		0.714,  0.505,  0.345,
		0.783,  0.290,  0.734,
		0.722,  0.645,  0.174,
		0.302,  0.455,  0.848,
		0.225,  0.587,  0.040,
		0.517,  0.713,  0.338,
		0.053,  0.959,  0.120,
		0.393,  0.621,  0.362,
		0.673,  0.211,  0.457,
		0.820,  0.883,  0.371,
		0.982,  0.099,  0.879
  ]        

  glClearColor(0.0,0,0.4,0)
  glDepthFunc(GL_LESS)
  glEnable(GL_DEPTH_TEST)
  
  shader = Shader()
  shader.initShaderFromGLSL(["glsl/tu01/vertex.glsl"],["glsl/tu01/fragment.glsl"])
  MVP_ID   = glGetUniformLocation(shader.program,"MVP")

  Projection = glm.perspective(glm.radians(45.0),800.0/480.0,0.1,100.0)
  View =  glm.lookAt(glm.vec3(4,3,-3), # Camera is at (4,3,-3), in World Space
                glm.vec3(0,0,0), #and looks at the (0.0.0))
                glm.vec3(0,1,0) ) #Head is up (set to 0,-1,0 to look upside-down)

  Model=  glm.mat4(1.0)
  MVP =  Projection * View *Model
  #print context.MVP
  #exit(0)

  vertexbuffer  = glGenBuffers(1)
  glBindBuffer(GL_ARRAY_BUFFER,vertexbuffer)
  glBufferData(GL_ARRAY_BUFFER,len(g_vertex_buffer_data)*4,(GLfloat * len(g_vertex_buffer_data))(*g_vertex_buffer_data),GL_STATIC_DRAW)


  colorbuffer  = glGenBuffers(1)
  glBindBuffer(GL_ARRAY_BUFFER,colorbuffer)
  glBufferData(GL_ARRAY_BUFFER,len(g_color_buffer_data)*4,(GLfloat * len(g_color_buffer_data))(*g_color_buffer_data),GL_STATIC_DRAW)

  while(True):
	  #print self.context.MVP
	  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
	  glUseProgram(shader.program)
	  glUniformMatrix4fv(MVP_ID, 1,GL_FALSE,glm.value_ptr(MVP))

	  glEnableVertexAttribArray(0)
	  glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer)

	  glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,0,ctypes.c_voidp(0)) # None means ctypes.c_voidp(0)

	  glEnableVertexAttribArray(1)
	  glBindBuffer(GL_ARRAY_BUFFER, colorbuffer)
	  glVertexAttribPointer(1,3,GL_FLOAT,GL_FALSE,0,ctypes.c_voidp(0))


	  glDrawArrays(GL_TRIANGLES, 0, 12*3) # 12*3 indices starting at 0 -> 12 triangles

	  glDisableVertexAttribArray(0)
	  glDisableVertexAttribArray(1)
time.sleep(5)

Here's the command that set everything:

pkg install termux-gui-package python-opengl numpy

pip install PyOpenGL

if i remember correctly that's all you need to install, but I'm not certain if it's actually just these

almost forgot, here's the repo that i downloaded the examples:

https://github.com/jcteng/python-opengl-tutorial

[tareksander]

Currently the python library has no support for shared hardware buffers. If you want to use OpenGL, you'll need to use the C library. Here is the OpenGL example.

I likely won't have time to implement this for the python library for a few months.

[Elsarques]

Currently the python library has no support for shared hardware buffers. If you want to use OpenGL, you'll need to use the C library. Here is the OpenGL example.

I likely won't have time to implement this for the python library for a few months.

I see, i'm trying to compile the example and it's throwing and EGL error:

buffer_gl.c:10:10: fatal error: EGL/egl.h: No such file or directory
10 | #include <EGL/egl.h>
| ^~~~~~~~~~~
compilation terminated.

How do I install EGL with C?

[tareksander]

I think the headers are in the mesa-dev package?

[Elsarques]

I think the headers are in the mesa-dev package?

The header worked now, but I still can't compile it, I have little to no knowledge in C, so I don't know what happened here

gcc -o buffer buffer_gl.c
/data/data/com.termux/files/usr/bin/ld: /data/data/com.termux/files/usr/tmp/ccPQigwS.o: in function checkGLError': buffer_gl.c:(.text+0x10): undefined reference to glGetError'
/data/data/com.termux/files/usr/bin/ld: /data/data/com.termux/files/usr/tmp/ccPQigwS.o: in function createShader': buffer_gl.c:(.text+0x70): undefined reference to glCreateShader'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x98): undefined reference to glShaderSource' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xb0): undefined reference to glCompileShader'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xdc): undefined reference to glGetShaderiv' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x10c): undefined reference to glGetShaderiv'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x148): undefined reference to glGetShaderInfoLog' /data/data/com.termux/files/usr/bin/ld: /data/data/com.termux/files/usr/tmp/ccPQigwS.o: in function main':
buffer_gl.c:(.text+0x1c0): undefined reference to tgui_connection_create' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x200): undefined reference to tgui_activity_create'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x258): undefined reference to tgui_hardware_buffer_create' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x2a8): undefined reference to tgui_hardware_buffer_create'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x2d4): undefined reference to eglGetDisplay' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x310): undefined reference to eglInitialize'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x320): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x388): undefined reference to eglQueryString'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x39c): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x474): undefined reference to eglGetProcAddress'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x488): undefined reference to eglGetProcAddress' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x49c): undefined reference to eglGetProcAddress'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x4b0): undefined reference to eglGetProcAddress' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x500): undefined reference to eglChooseConfig'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x510): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x55c): undefined reference to eglBindAPI'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x56c): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x5b4): undefined reference to eglCreateContext'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x5c8): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x61c): undefined reference to eglCreatePbufferSurface'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x630): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x664): undefined reference to eglMakeCurrent'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x674): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x69c): undefined reference to glGetString'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x714): undefined reference to glClearColor' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x738): undefined reference to glViewport'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x7b8): undefined reference to eglGetError' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x80c): undefined reference to eglGetError'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x838): undefined reference to glBindFramebuffer' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x854): undefined reference to glBindRenderbuffer'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x898): undefined reference to glFramebufferRenderbuffer' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x8b4): undefined reference to glBindFramebuffer'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x8d0): undefined reference to glBindRenderbuffer' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x914): undefined reference to glFramebufferRenderbuffer'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x930): undefined reference to glCreateProgram' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x980): undefined reference to glAttachShader'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x99c): undefined reference to glAttachShader' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x9b4): undefined reference to glLinkProgram'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0x9d0): undefined reference to glGetProgramiv' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xa00): undefined reference to glGetProgramiv'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xa3c): undefined reference to glGetProgramInfoLog' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xa70): undefined reference to glUseProgram'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xa94): undefined reference to glGetAttribLocation' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xab4): undefined reference to glEnableVertexAttribArray'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xaf8): undefined reference to tgui_poll_event' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xb64): undefined reference to tgui_create_surface_view'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xbb8): undefined reference to tgui_surface_view_config' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xbf0): undefined reference to tgui_send_touch_event'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xc04): undefined reference to tgui_focus' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xcac): undefined reference to tgui_focus'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xcfc): undefined reference to tgui_event_destroy' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xe18): undefined reference to glClear'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xe4c): undefined reference to glVertexAttribPointer' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xe6c): undefined reference to glDrawArrays'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xebc): undefined reference to glBindFramebuffer' /data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xed0): undefined reference to glFlush'
/data/data/com.termux/files/usr/bin/ld: buffer_gl.c:(.text+0xef4): undefined reference to `tgui_surface_view_set_buffer'
collect2: error: ld returned 1 exit status

[lualvsil]

you need to link the libraries, try like this:
gcc buffer_gl.c -o buffer -ltermuxgui -lEGL -lGLESv2