def __init__(self, name, program, geometry):
self.name = name
self.program = program
self.geometry = geometry
self.vertex_attr = glGetAttribLocation(self.program.id, b"vertex")
self.edge_attr = glGetAttribLocation(self.program.id, b"edge")
self.model_attr = glGetAttribLocation(self.program.id, b"turtle_model")
self.color_attr = glGetAttribLocation(self.program.id, b"turtle_color")
# create VAO to store Vertex attribute state for later
self.vao = GLuint()
glGenVertexArrays(1, self.vao)
# bind VAO to record array setup/state
glBindVertexArray(self.vao)
# load shape data into vertex buffer
self.vertex_buffer = VertexBuffer(GLfloat, GL_STATIC_DRAW)
self.vertex_buffer.load(geometry.edges)
self.vertex_buffer.partition(
[(self.vertex_attr, 4), (self.edge_attr, 3)]
)
# allocate/configure instanced buffers
# turtle model buffer
self.model_buffer = VertexBuffer(GLfloat, GL_STREAM_DRAW)
# mat4 is 4 sequential locations
array = [
(self.model_attr, 4),
(self.model_attr + 1, 4),
(self.model_attr + 2, 4),
(self.model_attr + 3, 4),
]
self.model_buffer.partition(array, divisor=1)
# turtle color buffer
self.color_buffer = VertexBuffer(GLfloat, GL_STREAM_DRAW)
# mat3 is 3 sequential locations
array = [
(self.color_attr, 3),
(self.color_attr + 1, 3),
(self.color_attr + 2, 3),
]
self.color_buffer.partition(array, divisor=1)
# VAO now configured, so unbind
glBindVertexArray(0)
def render(self, model, color, num_turtles):
"""Renders all turtles of a given shape"""
self.program.bind()
glBindVertexArray(self.vao)
self.model_buffer.load(model.data, model.byte_size)
self.color_buffer.load(color.data, color.byte_size)
glDrawArraysInstanced(
GL_TRIANGLES,
0,
len(self.geometry.edges) // 7, # 7 = 4 for vertex, 3 for edge
num_turtles
)
glBindVertexArray(0)
self.program.unbind()