I have this class below that works in Windows using OpenGL 3.0. However, in Linux this fails because it appears to be using an OpenGL 2.0 methods on an OpenGL 4.6 context. I get this error. How do tell the GtkGLArea in Python GTK to use OpenGL 4.6 libraries?
Traceback (most recent call last):
File "/home/user/git/DisplayIn/src/displayin/engine/openglrenderer.py", line 190, in render
self.setupGraphics()
File "/home/user/git/DisplayIn/src/displayin/engine/openglrenderer.py", line 120, in setupGraphics
self.initBuffers()
File "/home/user/git/DisplayIn/src/displayin/engine/openglrenderer.py", line 133, in initBuffers
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), ctypes.c_void_p(0))
File "/usr/local/lib/python3.10/dist-packages/OpenGL/latebind.py", line 63, in __call__
return self.wrapperFunction( self.baseFunction, *args, **named )
File "/usr/local/lib/python3.10/dist-packages/OpenGL/GL/VERSION/GL_2_0.py", line 469, in glVertexAttribPointer
contextdata.setValue( key, array )
File "/usr/local/lib/python3.10/dist-packages/OpenGL/contextdata.py", line 58, in setValue
context = getContext( context )
File "/usr/local/lib/python3.10/dist-packages/OpenGL/contextdata.py", line 40, in getContext
raise error.Error(
OpenGL.error.Error: Attempt to retrieve context when no valid context
This is the code of the class
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk
from OpenGL.GL import *
import numpy as np
import gc
VERTEX_SOURCE = '''
#version 330
layout (location=0) in vec3 position;
layout (location=1) in vec3 color;
layout (location=2) in vec2 texCoord;
out vec3 ourColor;
out vec2 TexCoord;
void main()
{
gl_Position = vec4(position,1.0);
ourColor = color;
TexCoord= vec2(texCoord.x,1.0-texCoord.y);
}'''
FRAGMENT_SOURCE ='''
#version 330
in vec3 ourColor;
in vec2 TexCoord;
out vec4 color;
uniform sampler2D ourTexture;
void main(){
color = texture(ourTexture, TexCoord);
};'''
recVertices = np.array([
# Positions Colors Texture Coords
1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 1.0, # Top Right 0
1.0, -1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 0.0, # Bottom Right 1
-1.0, -1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, # Bottom Left 2
-1.0, 1.0, 0.0, 1.0, 1.0, 0.0, 0.0, 1.0, # Top Left 3
1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 1.0, # Top Right 4
], dtype=np.float32)
def checkGlError(op: str):
error = glGetError()
if error is not None and error != 0:
print("after %s() glError (0x%x)", op, error)
# Based on examples:
# https://stackoverflow.com/questions/42153819/how-to-load-and-display-an-image-in-opengl-es-3-0-using-c
# https://stackoverflow.com/questions/47565884/use-of-the-gtk-glarea-in-pygobject-gtk3
class OpenGLRenderer(Gtk.GLArea):
def __init__(self):
Gtk.GLArea.__init__(self)
self.connect("realize", self.onRealize)
self.connect("render", self.onRender)
self.ctx = None
self.frame = self.createBlankScreenFrame()
self.area = None
self.shaderProgram = None
self.positionHandle = None
self.textureId = None
self.vao = None
self.vbos = None
self.version = None
def getVersion(self):
major = glGetIntegerv(GL_MAJOR_VERSION)
minor = glGetIntegerv(GL_MINOR_VERSION)
version = glGetString(GL_VERSION)
return major, minor, version
def createBlankScreenFrame(self):
frame = np.array([[[0, 0, 0]]], dtype=np.uint8)
return frame
def onRealize(self, area):
error = area.get_error()
if error != None:
print("your graphics card is probably too old : ", error)
else:
print(area, "realize... fine so far")
self.ctx = self.get_context()
self.ctx.make_current()
major, minor, self.version = self.getVersion()
print("OpenGL realized", self.ctx)
print("%s\n", self.version)
def onRender(self, area, ctx):
# Render will be invoked separately
# self.render(self.frame)
return True
def setupGraphics(self):
if self.shaderProgram is None:
# Load Shaders, Create program, Setup Graphics
vertexShader = glCreateShader(GL_VERTEX_SHADER)
glShaderSource(vertexShader, VERTEX_SOURCE)
glCompileShader(vertexShader)
status = glGetShaderiv(vertexShader, GL_COMPILE_STATUS)
print("Compile vertexShader status: " + str(status == GL_TRUE))
pixelShader = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(pixelShader, FRAGMENT_SOURCE)
glCompileShader(pixelShader)
status = glGetShaderiv(pixelShader, GL_COMPILE_STATUS)
print("Compile vertexShader status: " + str(status == GL_TRUE))
self.shaderProgram = glCreateProgram()
glAttachShader(self.shaderProgram, vertexShader)
glAttachShader(self.shaderProgram, pixelShader)
glLinkProgram(self.shaderProgram)
glBindFragDataLocation(self.shaderProgram, 0, "color")
self.positionHandle = glGetAttribLocation(self.shaderProgram, "position")
# Initalize Vertex Buffers
self.initBuffers()
def initBuffers(self):
# Initialize an buffer to store all the verticles and transfer them to the GPU
self.vao = glGenVertexArrays(1) # Generate VAO
self.vbos = glGenBuffers(1) # Generate VBO
glBindVertexArray(self.vao) # Bind the Vertex Array
glBindBuffer(GL_ARRAY_BUFFER, self.vbos) # Bind verticles array for OpenGL to use
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * len(recVertices), recVertices, GL_STATIC_DRAW)
# 1. set the vertex attributes pointers
# Position Attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), ctypes.c_void_p(0))
glEnableVertexAttribArray(0)
# Color Attribute
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), ctypes.c_void_p(3 * sizeof(GLfloat)))
glEnableVertexAttribArray(1)
# Texture Coordinate Attribute
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), ctypes.c_void_p(6 * sizeof(GLfloat)))
glEnableVertexAttribArray(2)
glBindVertexArray(0) # 3. Unbind VAO
def generateTexture(self, frame):
# Delete previous frame
# del self.frame
# gc.collect()
# Update Frame
self.frame = frame
# Delete previous textures to avoid memory leak
if self.textureId is not None:
glDeleteTextures(1, [self.textureId])
# If we have a frame to display
if frame is not None:
# extract array from Image
h, w, d = frame.shape
# Frame is a 3 dimentional array where shape eg. (1920, 1080, 3)
# Where it is w, h, and 3 values for color
# https://www.educba.com/numpy-flatten/
pixels = frame.ravel(order = 'C')
# Generate Texture
self.textureId = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, self.textureId) # Bind our 2D texture so that following set up will be applied
# Set texture wrapping parameter
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)
# Set texture Filtering parameter
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGB, GL_UNSIGNED_BYTE, pixels)
glGenerateMipmap(GL_TEXTURE_2D)
glBindTexture(GL_TEXTURE_2D, 0) # Unbind 2D textures
def render(self, frame):
# Set OpenGL Render Context
if self.ctx is not None and frame is not None:
self.ctx.make_current()
# Initialize Graphics
self.setupGraphics()
# Generate Texture
self.generateTexture(frame)
# Clear Screen
glClearColor(0, 0, 1, 1)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
# Use Shader Program, Bind Vertex Array and Texture
glUseProgram(self.shaderProgram)
checkGlError("glUseProgram")
glActiveTexture(GL_TEXTURE0)
checkGlError("glActiveTexture")
glBindTexture(GL_TEXTURE_2D, self.textureId)
checkGlError("glBindTexture")
mlocation = glGetUniformLocation(self.shaderProgram, "ourTexture")
checkGlError("glGetUniformLocation")
glUniform1i(mlocation, 0)
checkGlError("glUniform1i")
glBindVertexArray(self.vao)
checkGlError("glBindVertexArray")
# Render Frame
glDrawArrays(GL_TRIANGLES, 0, 3)
glDrawArrays(GL_TRIANGLES, 2, 3)
# Queue Draw
glFlush()
self.queue_draw()
Any ideas on how to set the OpenGL version for GtkGLArea?
So it turns out, I got this error because I was using the app in Wayland. This code runs fine in X11 so I needed to add this code to be run sometime before the code above to make this app work in Wayland as well.
# Needed for Wayland Support for OpenGL in Linux
if 'WAYLAND_DISPLAY' in os.environ and 'PYOPENGL_PLATFORM' not in os.environ:
os.environ['PYOPENGL_PLATFORM'] = 'x11'