Skip to content

Instantly share code, notes, and snippets.

@ousttrue
Last active May 19, 2022 15:27
Show Gist options
  • Save ousttrue/c4ae334fc1505cdf4cd7 to your computer and use it in GitHub Desktop.
Save ousttrue/c4ae334fc1505cdf4cd7 to your computer and use it in GitHub Desktop.
PyOpenGL vbo sample
# coding: utf-8
# 20190825 rewrite
import sys
import array
import ctypes
import struct
from typing import Any
from OpenGL.GL import *
from OpenGL.GLUT import *
VS = '''
#version 330
in vec2 aPosition;
void main ()
{
gl_Position = vec4(aPosition, 0.5, 1);
}
'''
FS = '''
#version 330
out vec4 FragColor;
void main()
{
FragColor = vec4(1, 1, 1, 1);
}
'''
def load_shader(src: str, shader_type: int) -> int:
shader = glCreateShader(shader_type)
glShaderSource(shader, src)
glCompileShader(shader)
error = glGetShaderiv(shader, GL_COMPILE_STATUS)
if error != GL_TRUE:
info = glGetShaderInfoLog(shader)
glDeleteShader(shader)
raise Exception(info)
return shader
class Shader:
def __init__(self) -> None:
self.program = glCreateProgram()
def __del__(self) -> None:
glDeleteProgram(self.program)
def compile(self, vs_src: str, fs_src: str) -> None:
vs = load_shader(vs_src, GL_VERTEX_SHADER)
if not vs:
return
fs = load_shader(fs_src, GL_FRAGMENT_SHADER)
if not fs:
return
glAttachShader(self.program, vs)
glAttachShader(self.program, fs)
glLinkProgram(self.program)
error = glGetProgramiv(self.program, GL_LINK_STATUS)
glDeleteShader(vs)
glDeleteShader(fs)
if error != GL_TRUE:
info = glGetShaderInfoLog(self.program)
raise Exception(info)
def use(self):
glUseProgram(self.program)
def unuse(self):
glUseProgram(0)
class VBO:
def __init__(self) -> None:
self.vbo = glGenBuffers(1)
self.component_count = 0 # Vec2, Vec3, Vec4 などの2, 3, 4
self.vertex_count = 0
def __del__(self) -> None:
glDeleteBuffers(1, [self.vbo])
def bind(self) -> None:
glBindBuffer(GL_ARRAY_BUFFER, self.vbo)
def unbind(self) -> None:
glBindBuffer(GL_ARRAY_BUFFER, 0)
def set_vertex_attribute(self, component_count: int, bytelength: int,
data: any) -> None:
''' float2, 3, 4'''
self.component_count = component_count
stride = 4 * self.component_count
self.vertex_count = bytelength // stride
self.bind()
glBufferData(GL_ARRAY_BUFFER, bytelength, data, GL_STATIC_DRAW)
def set_slot(self, slot: int) -> None:
self.bind()
glEnableVertexAttribArray(slot)
glVertexAttribPointer(slot, self.component_count, GL_FLOAT, GL_FALSE, 0, None)
def draw(self) -> None:
glDrawArrays(GL_TRIANGLES, 0, self.vertex_count)
class IBO:
def __init__(self) -> None:
self.vbo = glGenBuffers(1)
self.index_count = 0
self.index_type = 0
def __del__(self) -> None:
glDeleteBuffers(1, [self.vbo])
def bind(self) -> None:
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.vbo)
def unbind(self) -> None:
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0)
def set_indices(self, stride: int, bytelength: int, data: Any) -> None:
self.index_count = bytelength // stride
self.bind()
if stride == 1:
self.index_type = GL_UNSIGNED_BYT
elif stride == 2:
self.index_type = GL_UNSIGNED_SHORT
elif stride == 4:
self.index_type = GL_UNSIGNED_INT
glBufferData(GL_ELEMENT_ARRAY_BUFFER, bytelength, data, GL_STATIC_DRAW)
def draw(self) -> None:
glDrawElements(GL_TRIANGLES, self.index_count, self.index_type, None)
class Triangle:
def __init__(self) -> None:
self.vbo: VBO = None
self.ibo: IBO = None
self.shader: Shader = None
self.positions = (-1.0, -1.0, 1.0, -1.0, 0.0, 1.0)
self.indices = (0, 1, 2)
def initialize(self):
self.shader = Shader()
self.shader.compile(VS, FS)
self.vbo = VBO()
self.ibo = IBO()
if False:
# Error
self.vbo.set_vertex_attribute(2, 4 * 2 * 3,
array.array('f', self.positions))
self.ibo.set_indices(4, 12, array.array('I', self.indices))
elif True:
# OK
self.vbo.set_vertex_attribute(2, 4 * 2 * 3, (ctypes.c_float *
6)(*self.positions))
self.ibo.set_indices(4, 12, (ctypes.c_uint * 3)(*self.indices))
elif False:
# not work
self.vbo.set_vertex_attribute(2, 4 * 2 * 3,
memoryview(struct.pack("6f", *self.positions)))
self.ibo.set_indices(4, 12, memoryview(struct.pack("3I", *self.indices)))
else:
# OK
self.vbo.set_vertex_attribute(2, 4 * 2 * 3,
struct.pack("6f", *self.positions))
self.ibo.set_indices(4, 12, struct.pack("3I", *self.indices))
def draw(self) -> None:
if not self.vbo:
self.initialize()
self.shader.use()
self.vbo.set_slot(0)
self.ibo.bind()
self.ibo.draw()
self.ibo.unbind()
self.vbo.unbind()
self.shader.unuse()
def main():
glutInit(sys.argv)
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
# glutInitContextVersion(3, 3) # this call cause an error when glVertexAttribPointer
glutInitContextFlags(GLUT_CORE_PROFILE | GLUT_DEBUG)
glutInitWindowSize(256, 256)
glutCreateWindow(b"vbo")
print(glGetString(GL_VERSION))
print(
f'VERSION: {glGetInteger(GL_MAJOR_VERSION)}.{glGetInteger(GL_MINOR_VERSION)}'
)
triangle = Triangle()
def disp_func():
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
triangle.draw()
glFlush()
glutSwapBuffers()
glutDisplayFunc(disp_func)
# glutIdleFunc(disp_func)
def reshape_func(w, h):
glViewport(0, 0, w, h)
glutReshapeFunc(reshape_func)
glClearColor(0.0, 0.0, 0.0, 0.0)
glClearDepth(1.0)
glDepthFunc(GL_LESS)
glEnable(GL_DEPTH_TEST)
glutMainLoop()
if __name__ == "__main__":
main()
@CLandel89
Copy link

You can make array.array(...) work by converting it to a byte string: array.array(...).tobytes()

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment