I am trying to render multiple objects in pyopengl using pyqt5. After following tutorials I created a 3D mesh which uploads a wavefront obj file and renders it with texture. This worked for me:
class Model:
def __init__(self, file_name, texture_name):
self.object = ObjectLoader()
self.object.load_model(file_name)
//creating and compiling shaders
glUseProgram(shader)
vertex_buffer_object = GLuint(0)
glGenBuffers(1, vertex_buffer_object)
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object)
glBufferData(GL_ARRAY_BUFFER, len(self.object.model) * 4, self.object.c_model, GL_DYNAMIC_DRAW)
glDrawArrays(GL_TRIANGLES, 0, len(self.object.vertex_index))
# vertices
vertex_offset = 0
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(vertex_offset))
glEnableVertexAttribArray(0)
# textures
texture_offset = len(self.object.vertex_index) * 12
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 2, ctypes.c_void_p(texture_offset))
glEnableVertexAttribArray(1)
# normals
normal_offset = texture_offset + len(self.object.texture_index) * 8
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(normal_offset))
glEnableVertexAttribArray(2)
texture = GLuint(0)
glGenTextures(1, texture)
glBindTexture(GL_TEXTURE_2D, texture)
# texture wrapping
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# texture filtering
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
image = Image.open(texture_name)
flipped_image = image.transpose(Image.FLIP_TOP_BOTTOM)
image_data = image.convert("RGB").tobytes()
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width, image.height, 0, GL_RGB, GL_UNSIGNED_BYTE, image_data)
// setting the view, projection etc matrix
Since I am working with PyQt5, I have this class were I load the object:
class Obj(QOpenGLWidget):
def __init__(self, parent):
QOpenGLWidget.__init__(self, parent)
def initializeGL(self):
glClearColor(82/255, 95/255, 107/255, 1.0)
glEnable(GL_DEPTH_TEST)
self.model = Model("....obj", "texture.png")
def paintGL(self):
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glDrawArrays(GL_TRIANGLES, 0, len(self.model.object.vertex_index))
self.update()
def resizeGL(self, width, height):
glViewport(0, 0, width, height)
What I am struggling with is creating in the Obj class another Model. I tried creating it in initializeGL and rendering in paintGL with another glDrawArrays call, but nothing happened, or nothing expected... Any idea of what I am doing wrong?
You have to use a Vertex Array Object. A Vertex Array Object stores all of the state needed to supply vertex data.
The constructor of the model only creates all the required OpenGL objects. The shader program is not part of the model. Use the same program for all models:
class Model:
def __init__(self, file_name, texture_name):
self.object = ObjectLoader()
self.object.load_model(file_name)
# create vertex array object
self.vao = glGenVertexArrays(1)
glBindVertexArray(self.vao)
vertex_buffer_object = GLuint(0)
glGenBuffers(1, vertex_buffer_object)
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object)
glBufferData(GL_ARRAY_BUFFER, len(self.object.model) * 4, self.object.c_model, GL_DYNAMIC_DRAW)
glDrawArrays(GL_TRIANGLES, 0, len(self.object.vertex_index))
# vertices
vertex_offset = 0
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(vertex_offset))
glEnableVertexAttribArray(0)
# textures
texture_offset = len(self.object.vertex_index) * 12
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 2, ctypes.c_void_p(texture_offset))
glEnableVertexAttribArray(1)
# normals
normal_offset = texture_offset + len(self.object.texture_index) * 8
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, self.object.model.itemsize * 3, ctypes.c_void_p(normal_offset))
glEnableVertexAttribArray(2)
# create texture
self.texture = GLuint(0)
glGenTextures(1, self.texture)
glBindTexture(GL_TEXTURE_2D, self.texture)
# texture wrapping
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# texture filtering
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
image = Image.open(texture_name)
flipped_image = image.transpose(Image.FLIP_TOP_BOTTOM)
image_data = image.convert("RGB").tobytes()
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, image.width, image.height, 0, GL_RGB, GL_UNSIGNED_BYTE, image_data)
Add a method to the class which binds the OpenGL objects (VAO and texture) and draws the mesh:
class Model:
# [...]
def draw(self):
// bind texture
glBindTexture(GL_TEXTURE_2D, self.texture)
// create vertex array object
glBindVertexArray(self.vao)
// draw object
glDrawArrays(GL_TRIANGLES, 0, len(self.object.vertex_index))
With this setup you can draw multiple models:
class Obj(QOpenGLWidget):
def __init__(self, parent):
QOpenGLWidget.__init__(self, parent)
def initializeGL(self):
glClearColor(82/255, 95/255, 107/255, 1.0)
glEnable(GL_DEPTH_TEST)
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
self.model1 = Model("....obj", "texture.png")
self.model2 = Model("....obj", "texture2.png")
# [...]
def paintGL(self):
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
# install program
glUseProgram(self.shader)
# setting the view, projection etc matrix
# [...]
self.model1.draw()
self.model2.draw()
# [...]
self.update()
def resizeGL(self, width, height):
glViewport(0, 0, width, height)
The models can be organized in a list, too:
class Obj(QOpenGLWidget):
# [...]
def initializeGL(self):
# [...]
self.models = [
Model("....obj", "texture.png"),
Model("....obj", "texture2.png")
# [...]
]
def paintGL(self):
# [...]
for model in self.models:
model.draw()
# [...]