Framebuffer issue (render to texture) with GTK3 GLArea vs GLFW: Identical OpenGL program works in GLFW but not GTK3's GLArea
About my project: I am working with OpenGL3.2 on Linux and I have built a basic application using GTK3 with a GLArea widget. The program is written in Python using the PyCharm IDE. The project interpreter is set to Python 3.8 and I have loaded up the following packages: Pillow 7.1.2, PyGObject 3.36.1, PyOpenGL 3.1.5, numpy 1.18, pyrr 0.10.3 and glfw 1.11.2 (see image at bottom)
My Problem:
I have a program that runs correctly using GLFW but will not run correctly using GTK3's GLArea. I am trying to render to a texture using a custom framebuffer object The GTK3 based program does not successfully render to the custom framebuffer. However, the GLFW based program renders just fine. There is no difference in the OpenGL code. I am only changing the windowing code. Is there something I need to enable with GTK3 in order to use custom framebuffers? The documentation for GTK3 (here) only indicates that special flags need to be set to enable the depth buffer and the stencil buffer (I have enabled both of these) but nothing related to custom texture buffers.
Any and all insights greatly appreciated.
Here is the problematic GTK3 GLArea program:
import sys
import gi, pyrr
import numpy
gi.require_version('Gtk', '3.0')
from pyrr import matrix44, Vector3
from gi.repository import Gtk
from OpenGL.GL import *
from OpenGL.GL.shaders import compileProgram
from PIL import Image
class GLCanvas(Gtk.GLArea):
def __init__(self):
Gtk.GLArea.__init__(self)
self.set_required_version(3, 2) # Sets the version of OpenGL required by this OpenGL program
self.connect("realize", self.on_initialize) # This signal is used to initialize the OpenGL state
self.connect("render", self.on_render) # This signal is emitted for each frame that is rendered
self.add_tick_callback(self.tick) # This is a frame time clock that is called each time a frame is rendered
self.set_start_time = False # Boolean to track whether the clock has been initialized
self.set_has_depth_buffer(True)
self.set_has_stencil_buffer(True)
def tick(self, widget, frame_clock):
self.current_frame_time = frame_clock.get_frame_time() # Gets the current timestamp in microseconds
if self.set_start_time == False: # Initializes the timer at the start of the program
self.starting_time = self.current_frame_time # Stores the timestamp set when the program was initalized
self.set_start_time = True # Prevents the initialization routine from running again in this instance
self.application_clock = (self.current_frame_time - self.starting_time)/1000000 # Calculate the total number of seconds that the program has been running
return True # Returns true to indicate that tick callback should contine to be called
def on_initialize(self, gl_area):
# Prints information about our OpenGL Context
opengl_context = self.get_context() # Retrieves the Gdk.GLContext used by gl_area
opengl_context.make_current() # Makes the Gdk.GLContext current to the drawing surfaced used by Gtk.GLArea
major, minor = opengl_context.get_version() # Gets the version of OpenGL currently used by the opengl_context
print("\033[93m OpenGL context created successfully.\n -- Using OpenGL Version \033[94m" + str(major) + "." + str(minor) + "\033[0m")
# Checks to see if there were errors creating the context
if gl_area.get_error() != None:
print(gl_area.get_error())
# Get information about current GTK GLArea canvas
window = gl_area.get_allocation()
w_width, w_height = window.width, window.height
self.aspect_ratio = w_width / w_height
self.cube_positions = [(1.0, 1.0, 0.0), (0.0, 0.0, 0.0), (2.0, 0.0, 0.0)]
self.plane_position = matrix44.create_from_translation(Vector3([-3.0, 1.0, 0.0]))
cube = [-0.5, -0.5, 0.5, 0.0, 0.0,
0.5, -0.5, 0.5, 1.0, 0.0,
0.5, 0.5, 0.5, 1.0, 1.0,
-0.5, 0.5, 0.5, 0.0, 1.0,
-0.5, -0.5, -0.5, 0.0, 0.0,
0.5, -0.5, -0.5, 1.0, 0.0,
0.5, 0.5, -0.5, 1.0, 1.0,
-0.5, 0.5, -0.5, 0.0, 1.0,
0.5, -0.5, -0.5, 0.0, 0.0,
0.5, 0.5, -0.5, 1.0, 0.0,
0.5, 0.5, 0.5, 1.0, 1.0,
0.5, -0.5, 0.5, 0.0, 1.0,
-0.5, 0.5, -0.5, 0.0, 0.0,
-0.5, -0.5, -0.5, 1.0, 0.0,
-0.5, -0.5, 0.5, 1.0, 1.0,
-0.5, 0.5, 0.5, 0.0, 1.0,
-0.5, -0.5, -0.5, 0.0, 0.0,
0.5, -0.5, -0.5, 1.0, 0.0,
0.5, -0.5, 0.5, 1.0, 1.0,
-0.5, -0.5, 0.5, 0.0, 1.0,
0.5, 0.5, -0.5, 0.0, 0.0,
-0.5, 0.5, -0.5, 1.0, 0.0,
-0.5, 0.5, 0.5, 1.0, 1.0,
0.5, 0.5, 0.5, 0.0, 1.0]
cube = numpy.array(cube, dtype=numpy.float32)
self.cube_indices = [0, 1, 2, 2, 3, 0,
4, 5, 6, 6, 7, 4,
8, 9, 10, 10, 11, 8,
12, 13, 14, 14, 15, 12,
16, 17, 18, 18, 19, 16,
20, 21, 22, 22, 23, 20]
self.cube_indices = numpy.array(self.cube_indices, dtype=numpy.uint32)
plane = [-0.5, -0.5, 0.0, 0.0, 0.0,
2.0, -0.5, 0.0, 1.0, 0.0,
2.0, 1.0, 0.0, 1.0, 1.0,
-0.5, 1.0, 0.0, 0.0, 1.0]
plane = numpy.array(plane, dtype=numpy.float32)
self.plane_indices = [0, 1, 2, 2, 3, 0]
self.plane_indices = numpy.array(self.plane_indices, dtype=numpy.uint32)
vertex_shader = """
#version 330
in layout(location = 0) vec3 position;
in layout(location = 1) vec2 textCoords;
uniform mat4 vp;
uniform mat4 model;
out vec2 outText;
void main()
{
gl_Position = vp * model * vec4(position, 1.0f);
outText = textCoords;
}
"""
fragment_shader = """
#version 330
in vec2 outText;
out vec4 outColor;
uniform sampler2D renderedTexture;
void main()
{
outColor = texture(renderedTexture, outText);
}
"""
shader = OpenGL.GL.shaders.compileProgram(OpenGL.GL.shaders.compileShader(vertex_shader, GL_VERTEX_SHADER),
OpenGL.GL.shaders.compileShader(fragment_shader, GL_FRAGMENT_SHADER))
# cube VAO
self.cube_vao = glGenVertexArrays(1)
glBindVertexArray(self.cube_vao)
cube_VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, cube_VBO)
glBufferData(GL_ARRAY_BUFFER, cube.itemsize * len(cube), cube, GL_STATIC_DRAW)
cube_EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, cube_EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, self.cube_indices.itemsize * len(self.cube_indices), self.cube_indices, GL_STATIC_DRAW)
# position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, cube.itemsize * 5, ctypes.c_void_p(0))
glEnableVertexAttribArray(0)
# textures
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, cube.itemsize * 5, ctypes.c_void_p(12))
glEnableVertexAttribArray(1)
glBindVertexArray(0)
# plane VAO
self.plane_vao = glGenVertexArrays(1)
glBindVertexArray(self.plane_vao)
plane_VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, plane_VBO)
glBufferData(GL_ARRAY_BUFFER, plane.itemsize * len(plane), plane, GL_STATIC_DRAW)
plane_EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, plane_EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, self.plane_indices.itemsize * len(self.plane_indices), self.plane_indices,
GL_STATIC_DRAW)
# position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, plane.itemsize * 5, ctypes.c_void_p(0))
glEnableVertexAttribArray(0)
# textures
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, plane.itemsize * 5, ctypes.c_void_p(12))
glEnableVertexAttribArray(1)
glBindVertexArray(0)
###########################################################################################
self.plane_texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, self.plane_texture)
# texture wrapping params
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# texture filtering params
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_RGBA, w_width, w_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, None)
glBindTexture(GL_TEXTURE_2D, 0)
depth_buff = glGenRenderbuffers(1)
glBindRenderbuffer(GL_RENDERBUFFER, depth_buff)
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, w_width, w_height)
self.FBO = glGenFramebuffers(1)
glBindFramebuffer(GL_FRAMEBUFFER, self.FBO)
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, self.plane_texture, 0)
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depth_buff)
glBindFramebuffer(GL_FRAMEBUFFER, 0)
###########################################################################################
self.crate_texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, self.crate_texture)
# Set the texture wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# Set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
# load image
image = Image.open("models/crate.jpg")
img_data = numpy.array(list(image.getdata()), numpy.uint8)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width, image.height, 0, GL_RGB, GL_UNSIGNED_BYTE, img_data)
glBindTexture(GL_TEXTURE_2D, 0)
###########################################################################################
glEnable(GL_DEPTH_TEST)
view = matrix44.create_from_translation(Vector3([0.0, 0.0, -5.0]))
projection = matrix44.create_perspective_projection_matrix(45.0, self.aspect_ratio, 0.1, 100.0)
vp = matrix44.multiply(view, projection)
glUseProgram(shader)
vp_loc = glGetUniformLocation(shader, "vp")
self.model_loc = glGetUniformLocation(shader, "model")
glUniformMatrix4fv(vp_loc, 1, GL_FALSE, vp)
return True
def on_render(self, gl_area, gl_context):
glClearColor(0.2, 0.25, 0.27, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
rot_y = pyrr.Matrix44.from_y_rotation(self.application_clock * 2)
# draw to the default frame buffer
glBindVertexArray(self.cube_vao)
glBindTexture(GL_TEXTURE_2D, self.crate_texture)
for i in range(len(self.cube_positions)):
model = matrix44.create_from_translation(self.cube_positions[i])
if i == 0:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, rot_y * model)
elif i == 1:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
else:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
glDrawElements(GL_TRIANGLES, len(self.cube_indices), GL_UNSIGNED_INT, None)
# draw to the custom frame buffer
glBindFramebuffer(GL_FRAMEBUFFER, self.FBO)
glClearColor(0.0, 0.0, 0.0, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
for i in range(len(self.cube_positions)):
model = matrix44.create_from_translation(self.cube_positions[i])
if i == 0:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, rot_y * model)
elif i == 1:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
else:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
glDrawElements(GL_TRIANGLES, len(self.cube_indices), GL_UNSIGNED_INT, None)
glBindVertexArray(0)
glBindFramebuffer(GL_FRAMEBUFFER, 0)
# draw the plane
glBindVertexArray(self.plane_vao)
glBindTexture(GL_TEXTURE_2D, self.plane_texture)
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, self.plane_position)
glDrawElements(GL_TRIANGLES, len(self.plane_indices), GL_UNSIGNED_INT, None)
glBindVertexArray(0)
self.queue_draw() # Schedules a redraw for Gtk.GLArea
class RootWindow(Gtk.Application):
def __init__(self):
Gtk.Application.__init__(self)
def do_activate(self):
window = Gtk.Window(application=self)
window.set_title("Render To Texture")
window.set_default_size(1280, 720)
window.set_position(Gtk.WindowPosition.CENTER)
window.add(GLCanvas())
window.show_all()
win = RootWindow()
exit_status = win.run(sys.argv)
sys.exit(exit_status)
Here is the full working GLFW program (original source):
import glfw
from OpenGL.GL import *
import OpenGL.GL.shaders
import numpy
import pyrr
from pyrr import matrix44, Vector3
from PIL import Image
def window_resize(window, width, height):
glViewport(0, 0, width, height)
cube_positions = [(1.0, 1.0, 0.0), (0.0, 0.0, 0.0), (2.0, 0.0, 0.0)]
plane_position = matrix44.create_from_translation(Vector3([-3.0, 1.0, 0.0]))
def main():
if not glfw.init():
return
w_width, w_height = 1280, 720
aspect_ratio = w_width / w_height
window = glfw.create_window(w_width, w_height, "My OpenGL window", None, None)
if not window:
glfw.terminate()
return
glfw.make_context_current(window)
glfw.set_window_size_callback(window, window_resize)
cube = [-0.5, -0.5, 0.5, 0.0, 0.0,
0.5, -0.5, 0.5, 1.0, 0.0,
0.5, 0.5, 0.5, 1.0, 1.0,
-0.5, 0.5, 0.5, 0.0, 1.0,
-0.5, -0.5, -0.5, 0.0, 0.0,
0.5, -0.5, -0.5, 1.0, 0.0,
0.5, 0.5, -0.5, 1.0, 1.0,
-0.5, 0.5, -0.5, 0.0, 1.0,
0.5, -0.5, -0.5, 0.0, 0.0,
0.5, 0.5, -0.5, 1.0, 0.0,
0.5, 0.5, 0.5, 1.0, 1.0,
0.5, -0.5, 0.5, 0.0, 1.0,
-0.5, 0.5, -0.5, 0.0, 0.0,
-0.5, -0.5, -0.5, 1.0, 0.0,
-0.5, -0.5, 0.5, 1.0, 1.0,
-0.5, 0.5, 0.5, 0.0, 1.0,
-0.5, -0.5, -0.5, 0.0, 0.0,
0.5, -0.5, -0.5, 1.0, 0.0,
0.5, -0.5, 0.5, 1.0, 1.0,
-0.5, -0.5, 0.5, 0.0, 1.0,
0.5, 0.5, -0.5, 0.0, 0.0,
-0.5, 0.5, -0.5, 1.0, 0.0,
-0.5, 0.5, 0.5, 1.0, 1.0,
0.5, 0.5, 0.5, 0.0, 1.0]
cube = numpy.array(cube, dtype=numpy.float32)
cube_indices = [ 0, 1, 2, 2, 3, 0,
4, 5, 6, 6, 7, 4,
8, 9, 10, 10, 11, 8,
12, 13, 14, 14, 15, 12,
16, 17, 18, 18, 19, 16,
20, 21, 22, 22, 23, 20]
cube_indices = numpy.array(cube_indices, dtype=numpy.uint32)
plane = [-0.5, -0.5, 0.0, 0.0, 0.0,
2.0, -0.5, 0.0, 1.0, 0.0,
2.0, 1.0, 0.0, 1.0, 1.0,
-0.5, 1.0, 0.0, 0.0, 1.0]
plane = numpy.array(plane, dtype=numpy.float32)
plane_indices = [0, 1, 2, 2, 3, 0]
plane_indices = numpy.array(plane_indices, dtype=numpy.uint32)
vertex_shader = """
#version 330
in layout(location = 0) vec3 position;
in layout(location = 1) vec2 textCoords;
uniform mat4 vp;
uniform mat4 model;
out vec2 outText;
void main()
{
gl_Position = vp * model * vec4(position, 1.0f);
outText = textCoords;
}
"""
fragment_shader = """
#version 330
in vec2 outText;
out vec4 outColor;
uniform sampler2D renderedTexture;
void main()
{
outColor = texture(renderedTexture, outText);
}
"""
shader = OpenGL.GL.shaders.compileProgram(OpenGL.GL.shaders.compileShader(vertex_shader, GL_VERTEX_SHADER),
OpenGL.GL.shaders.compileShader(fragment_shader, GL_FRAGMENT_SHADER))
# cube VAO
cube_vao = glGenVertexArrays(1)
glBindVertexArray(cube_vao)
cube_VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, cube_VBO)
glBufferData(GL_ARRAY_BUFFER, cube.itemsize * len(cube), cube, GL_STATIC_DRAW)
cube_EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, cube_EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, cube_indices.itemsize * len(cube_indices), cube_indices, GL_STATIC_DRAW)
# position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, cube.itemsize * 5, ctypes.c_void_p(0))
glEnableVertexAttribArray(0)
# textures
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, cube.itemsize * 5, ctypes.c_void_p(12))
glEnableVertexAttribArray(1)
glBindVertexArray(0)
# plane VAO
plane_vao = glGenVertexArrays(1)
glBindVertexArray(plane_vao)
plane_VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, plane_VBO)
glBufferData(GL_ARRAY_BUFFER, plane.itemsize * len(plane), plane, GL_STATIC_DRAW)
plane_EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, plane_EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, plane_indices.itemsize * len(plane_indices), plane_indices, GL_STATIC_DRAW)
# position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, plane.itemsize * 5, ctypes.c_void_p(0))
glEnableVertexAttribArray(0)
# textures
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, plane.itemsize * 5, ctypes.c_void_p(12))
glEnableVertexAttribArray(1)
glBindVertexArray(0)
###########################################################################################
plane_texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, plane_texture)
# texture wrapping params
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# texture filtering params
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_RGBA, w_width, w_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, None)
glBindTexture(GL_TEXTURE_2D, 0)
depth_buff = glGenRenderbuffers(1)
glBindRenderbuffer(GL_RENDERBUFFER, depth_buff)
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, w_width, w_height)
FBO = glGenFramebuffers(1)
glBindFramebuffer(GL_FRAMEBUFFER, FBO)
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, plane_texture, 0)
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depth_buff)
glBindFramebuffer(GL_FRAMEBUFFER, 0)
###########################################################################################
crate_texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, crate_texture)
# Set the texture wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# Set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
# load image
image = Image.open("res/crate.jpg")
img_data = numpy.array(list(image.getdata()), numpy.uint8)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width, image.height, 0, GL_RGB, GL_UNSIGNED_BYTE, img_data)
glBindTexture(GL_TEXTURE_2D, 0)
###########################################################################################
glEnable(GL_DEPTH_TEST)
view = matrix44.create_from_translation(Vector3([0.0, 0.0, -5.0]))
projection = matrix44.create_perspective_projection_matrix(45.0, aspect_ratio, 0.1, 100.0)
vp = matrix44.multiply(view, projection)
glUseProgram(shader)
vp_loc = glGetUniformLocation(shader, "vp")
model_loc = glGetUniformLocation(shader, "model")
glUniformMatrix4fv(vp_loc, 1, GL_FALSE, vp)
while not glfw.window_should_close(window):
glfw.poll_events()
glClearColor(0.2, 0.25, 0.27, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
rot_y = pyrr.Matrix44.from_y_rotation(glfw.get_time() * 2)
# draw to the default frame buffer
glBindVertexArray(cube_vao)
glBindTexture(GL_TEXTURE_2D, crate_texture)
for i in range(len(cube_positions)):
model = matrix44.create_from_translation(cube_positions[i])
if i == 0:
glUniformMatrix4fv(model_loc, 1, GL_FALSE, rot_y * model)
elif i == 1:
glUniformMatrix4fv(model_loc, 1, GL_FALSE, model)
else:
glUniformMatrix4fv(model_loc, 1, GL_FALSE, model)
glDrawElements(GL_TRIANGLES, len(cube_indices), GL_UNSIGNED_INT, None)
# draw to the custom frame buffer
glBindFramebuffer(GL_FRAMEBUFFER, FBO)
glClearColor(0.0, 0.0, 0.0, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
for i in range(len(cube_positions)):
model = matrix44.create_from_translation(cube_positions[i])
if i == 0:
glUniformMatrix4fv(model_loc, 1, GL_FALSE, rot_y * model)
elif i == 1:
glUniformMatrix4fv(model_loc, 1, GL_FALSE, model)
else:
glUniformMatrix4fv(model_loc, 1, GL_FALSE, model)
glDrawElements(GL_TRIANGLES, len(cube_indices), GL_UNSIGNED_INT, None)
glBindVertexArray(0)
glBindFramebuffer(GL_FRAMEBUFFER, 0)
# draw the plane
glBindVertexArray(plane_vao)
glBindTexture(GL_TEXTURE_2D, plane_texture)
glUniformMatrix4fv(model_loc, 1, GL_FALSE, plane_position)
glDrawElements(GL_TRIANGLES, len(plane_indices), GL_UNSIGNED_INT, None)
glBindVertexArray(0)
glfw.swap_buffers(window)
glfw.terminate()
if __name__ == "__main__":
main()
Solution
Solution
It turns out that GLArea is not using framebuffer 0 as the default. The issue here is resetting the framebuffer back to 0 at the end of the rendering loop with glBindFramebuffer(GL_FRAMEBUFFER, 0). Instead, use default_ID = glGetIntegerv(GL_FRAMEBUFFER_BINDING) at the beginning of the rendering loop to get the current default ID. At the end of the loop, reset to the default framebuffer using glBindFramebuffer(GL_FRAMEBUFFER, default_ID).
import sys
import gi, pyrr
import numpy
gi.require_version('Gtk', '3.0')
from pyrr import matrix44, Vector3
from gi.repository import Gtk
from OpenGL.GL import *
from OpenGL.GL.shaders import compileProgram
from PIL import Image
class GLCanvas(Gtk.GLArea):
def __init__(self):
Gtk.GLArea.__init__(self)
self.set_required_version(3, 2) # Sets the version of OpenGL required by this OpenGL program
self.connect("realize", self.on_initialize) # This signal is used to initialize the OpenGL state
self.connect("render", self.on_render) # This signal is emitted for each frame that is rendered
self.add_tick_callback(self.tick) # This is a frame time clock that is called each time a frame is rendered
self.set_start_time = False # Boolean to track whether the clock has been initialized
self.set_has_depth_buffer(True)
self.set_has_stencil_buffer(True)
def tick(self, widget, frame_clock):
self.current_frame_time = frame_clock.get_frame_time() # Gets the current timestamp in microseconds
if self.set_start_time == False: # Initializes the timer at the start of the program
self.starting_time = self.current_frame_time # Stores the timestamp set when the program was initalized
self.set_start_time = True # Prevents the initialization routine from running again in this instance
self.application_clock = (self.current_frame_time - self.starting_time)/1000000 # Calculate the total number of seconds that the program has been running
return True # Returns true to indicate that tick callback should contine to be called
def on_initialize(self, gl_area):
# Prints information about our OpenGL Context
opengl_context = self.get_context() # Retrieves the Gdk.GLContext used by gl_area
opengl_context.make_current() # Makes the Gdk.GLContext current to the drawing surfaced used by Gtk.GLArea
major, minor = opengl_context.get_version() # Gets the version of OpenGL currently used by the opengl_context
# https://stackoverflow.com/questions/287871/how-to-print-colored-text-in-terminal-in-python
print("\033[93m OpenGL context created successfully.\n -- Using OpenGL Version \033[94m" + str(major) + "." + str(minor) + "\033[0m")
# Checks to see if there were errors creating the context
if gl_area.get_error() != None:
print(gl_area.get_error())
# Get information about current GTK GLArea canvas
window = gl_area.get_allocation()
w_width, w_height = window.width, window.height
self.aspect_ratio = w_width / w_height
self.cube_positions = [(1.0, 1.0, 0.0), (0.0, 0.0, 0.0), (2.0, 0.0, 0.0)]
self.plane_position = matrix44.create_from_translation(Vector3([-3.0, 1.0, 0.0]))
cube = [-0.5, -0.5, 0.5, 0.0, 0.0,
0.5, -0.5, 0.5, 1.0, 0.0,
0.5, 0.5, 0.5, 1.0, 1.0,
-0.5, 0.5, 0.5, 0.0, 1.0,
-0.5, -0.5, -0.5, 0.0, 0.0,
0.5, -0.5, -0.5, 1.0, 0.0,
0.5, 0.5, -0.5, 1.0, 1.0,
-0.5, 0.5, -0.5, 0.0, 1.0,
0.5, -0.5, -0.5, 0.0, 0.0,
0.5, 0.5, -0.5, 1.0, 0.0,
0.5, 0.5, 0.5, 1.0, 1.0,
0.5, -0.5, 0.5, 0.0, 1.0,
-0.5, 0.5, -0.5, 0.0, 0.0,
-0.5, -0.5, -0.5, 1.0, 0.0,
-0.5, -0.5, 0.5, 1.0, 1.0,
-0.5, 0.5, 0.5, 0.0, 1.0,
-0.5, -0.5, -0.5, 0.0, 0.0,
0.5, -0.5, -0.5, 1.0, 0.0,
0.5, -0.5, 0.5, 1.0, 1.0,
-0.5, -0.5, 0.5, 0.0, 1.0,
0.5, 0.5, -0.5, 0.0, 0.0,
-0.5, 0.5, -0.5, 1.0, 0.0,
-0.5, 0.5, 0.5, 1.0, 1.0,
0.5, 0.5, 0.5, 0.0, 1.0]
cube = numpy.array(cube, dtype=numpy.float32)
self.cube_indices = [0, 1, 2, 2, 3, 0,
4, 5, 6, 6, 7, 4,
8, 9, 10, 10, 11, 8,
12, 13, 14, 14, 15, 12,
16, 17, 18, 18, 19, 16,
20, 21, 22, 22, 23, 20]
self.cube_indices = numpy.array(self.cube_indices, dtype=numpy.uint32)
plane = [-0.5, -0.5, 0.0, 0.0, 0.0,
2.0, -0.5, 0.0, 1.0, 0.0,
2.0, 1.0, 0.0, 1.0, 1.0,
-0.5, 1.0, 0.0, 0.0, 1.0]
plane = numpy.array(plane, dtype=numpy.float32)
self.plane_indices = [0, 1, 2, 2, 3, 0]
self.plane_indices = numpy.array(self.plane_indices, dtype=numpy.uint32)
vertex_shader = """
#version 330
in vec3 position;
in vec2 textCoords;
uniform mat4 vp;
uniform mat4 model;
out vec2 outText;
void main()
{
gl_Position = vp * model * vec4(position, 1.0f);
outText = textCoords;
}
"""
fragment_shader = """
#version 330
in vec2 outText;
out vec4 outColor;
uniform sampler2D renderedTexture;
void main()
{
outColor = texture(renderedTexture, outText);
}
"""
shader = OpenGL.GL.shaders.compileProgram(OpenGL.GL.shaders.compileShader(vertex_shader, GL_VERTEX_SHADER),
OpenGL.GL.shaders.compileShader(fragment_shader, GL_FRAGMENT_SHADER))
# cube VAO
self.cube_vao = glGenVertexArrays(1)
glBindVertexArray(self.cube_vao)
cube_VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, cube_VBO)
glBufferData(GL_ARRAY_BUFFER, cube.itemsize * len(cube), cube, GL_STATIC_DRAW)
cube_EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, cube_EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, self.cube_indices.itemsize * len(self.cube_indices), self.cube_indices, GL_STATIC_DRAW)
# position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, cube.itemsize * 5, ctypes.c_void_p(0))
glEnableVertexAttribArray(0)
# textures
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, cube.itemsize * 5, ctypes.c_void_p(12))
glEnableVertexAttribArray(1)
glBindVertexArray(0)
# plane VAO
self.plane_vao = glGenVertexArrays(1)
glBindVertexArray(self.plane_vao)
plane_VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, plane_VBO)
glBufferData(GL_ARRAY_BUFFER, plane.itemsize * len(plane), plane, GL_STATIC_DRAW)
plane_EBO = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, plane_EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, self.plane_indices.itemsize * len(self.plane_indices), self.plane_indices,
GL_STATIC_DRAW)
# position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, plane.itemsize * 5, ctypes.c_void_p(0))
glEnableVertexAttribArray(0)
# textures
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, plane.itemsize * 5, ctypes.c_void_p(12))
glEnableVertexAttribArray(1)
glBindVertexArray(0)
###########################################################################################
self.plane_texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, self.plane_texture)
# texture wrapping params
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# texture filtering params
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_RGBA, w_width, w_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, None)
glBindTexture(GL_TEXTURE_2D, 0)
depth_buff = glGenRenderbuffers(1)
glBindRenderbuffer(GL_RENDERBUFFER, depth_buff)
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, w_width, w_height)
self.FBO = glGenFramebuffers(1)
glBindFramebuffer(GL_FRAMEBUFFER, self.FBO)
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, self.plane_texture, 0)
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depth_buff)
glBindFramebuffer(GL_FRAMEBUFFER, 0)
###########################################################################################
self.crate_texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, self.crate_texture)
# Set the texture wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# Set texture filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
# load image
image = Image.open("models/crate.jpg")
img_data = numpy.array(list(image.getdata()), numpy.uint8)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width, image.height, 0, GL_RGB, GL_UNSIGNED_BYTE, img_data)
glBindTexture(GL_TEXTURE_2D, 0)
###########################################################################################
glEnable(GL_DEPTH_TEST)
view = matrix44.create_from_translation(Vector3([0.0, 0.0, -5.0]))
projection = matrix44.create_perspective_projection_matrix(45.0, self.aspect_ratio, 0.1, 100.0)
vp = matrix44.multiply(view, projection)
glUseProgram(shader)
vp_loc = glGetUniformLocation(shader, "vp")
self.model_loc = glGetUniformLocation(shader, "model")
glUniformMatrix4fv(vp_loc, 1, GL_FALSE, vp)
return True
def on_render(self, gl_area, gl_context):
default_ID = glGetIntegerv(GL_FRAMEBUFFER_BINDING)
glClearColor(0.2, 0.25, 0.27, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
rot_y = pyrr.Matrix44.from_y_rotation(self.application_clock * 2)
# draw to the default frame buffer
glBindVertexArray(self.cube_vao)
glBindTexture(GL_TEXTURE_2D, self.crate_texture)
for i in range(len(self.cube_positions)):
model = matrix44.create_from_translation(self.cube_positions[i])
if i == 0:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, rot_y * model)
elif i == 1:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
else:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
glDrawElements(GL_TRIANGLES, len(self.cube_indices), GL_UNSIGNED_INT, None)
# draw to the custom frame buffer
glBindFramebuffer(GL_FRAMEBUFFER, self.FBO)
glClearColor(0.0, 0.0, 0.0, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
for i in range(len(self.cube_positions)):
model = matrix44.create_from_translation(self.cube_positions[i])
if i == 0:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, rot_y * model)
elif i == 1:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
else:
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, model)
glDrawElements(GL_TRIANGLES, len(self.cube_indices), GL_UNSIGNED_INT, None)
glBindFramebuffer(GL_FRAMEBUFFER, default_ID)
glBindVertexArray(0)
# draw the plane
glBindVertexArray(self.plane_vao)
glBindTexture(GL_TEXTURE_2D, self.plane_texture)
glUniformMatrix4fv(self.model_loc, 1, GL_FALSE, self.plane_position)
glDrawElements(GL_TRIANGLES, len(self.plane_indices), GL_UNSIGNED_INT, None)
glBindVertexArray(0)
self.queue_draw() # Schedules a redraw for Gtk.GLArea
class RootWindow(Gtk.Application):
def __init__(self):
Gtk.Application.__init__(self)
def do_activate(self):
window = Gtk.Window(application=self)
window.set_title("Render To Texture")
window.set_default_size(1280, 720)
window.set_position(Gtk.WindowPosition.CENTER)
window.add(GLCanvas())
window.show_all()
win = RootWindow()
exit_status = win.run(sys.argv)
sys.exit(exit_status)
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