PyOpenGL 透视投影
Posted
技术标签:
【中文标题】PyOpenGL 透视投影【英文标题】：PyOpenGL Perspective Projection 【发布时间】：2017-08-04 19:40:29 【问题描述】：我对 PyOpenGL 比较陌生，并开始学习转换和模型、视图和投影矩阵。这很好，直到我编译并运行我的代码，发现我的对象突然消失了，老实说，我不知道 OpenGL 是否正在剪切我的对象，或者只是因为某些相机错误而没有显示它，但我相信它有一些东西与在我的代码中实现的投影矩阵有关，因为当我从我的代码中删除投影矩阵并运行我的程序时，一切突然又恢复了工作，除了我没有实现透视投影的事实。无论如何，任何人都会非常感激：D
这是我的 PyOpenGL 代码。
import OpenGL, PIL, pygame, numpy, pyrr, math, sys, os
from OpenGL.GL import *
from PIL import Image
from pyrr import Matrix44, Vector4, Vector3, Quaternion
VERT_DATA = numpy.array([0.5, 0.5, 0.0,
0.5, -0.5, 0.0,
-0.5, -0.5, 0.0,
-0.5, 0.5, 0.0],
dtype="float32")
COLOR_DATA = numpy.array([1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 1.0, 1.0, 1.0],
dtype="float32")
TEXTURE_COORD_DATA = numpy.array([0.5, 0.5,
0.5, -0.5,
-0.5, -0.5,
-0.5, 0.5],
dtype="float32")
INDICES = numpy.array([0, 1, 3,
1, 2, 3],
dtype="int32")
class GLProgram:
def __init__(self):
self.gl_program = glCreateProgram()
self.mvp_matrix = self.projection()
self.shaders()
self.gl_buffers()
def gl_texture(self, texture_path):
image = Image.open(texture_path).transpose(Image.FLIP_TOP_BOTTOM)
image_data = numpy.fromstring(image.tobytes(), numpy.uint8)
width, height = image.size
texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, texture)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image_data)
glGenerateMipmap(GL_TEXTURE_2D)
return texture
def gl_buffers(self):
self.vao = glGenVertexArrays(1)
glBindVertexArray(self.vao)
self.pos_vbo = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.pos_vbo)
glBufferData(GL_ARRAY_BUFFER, VERT_DATA, GL_STATIC_DRAW)
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(0)
self.text_coord_vbo = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.text_coord_vbo)
glBufferData(GL_ARRAY_BUFFER, TEXTURE_COORD_DATA, GL_STATIC_DRAW)
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(1)
self.pos_ebo = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.pos_ebo)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.pos_ebo)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, INDICES, GL_STATIC_DRAW)
self.brick_texture = self.gl_texture("check.jpg")
def shaders(self):
vertex_shader = glCreateShader(GL_VERTEX_SHADER)
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER)
with open("VertexShader.vert", "r") as vert_file:
vert_source = vert_file.read()
with open("FragmentShader.frag", "r") as frag_file:
frag_source = frag_file.read()
glShaderSource(vertex_shader, vert_source)
glShaderSource(fragment_shader, frag_source)
glCompileShader(vertex_shader)
if not glGetShaderiv(vertex_shader, GL_COMPILE_STATUS):
info_log = glGetShaderInfoLog(vertex_shader)
print ("Compilation Failure for " + vertex_shader + " shader:\n" + info_log)
glCompileShader(fragment_shader)
if not glGetShaderiv(fragment_shader, GL_COMPILE_STATUS):
info_log = glGetShaderInfoLog(fragment_shader)
print ("Compilation Failure for " + fragment_shader + " shader:\n" + info_log)
glAttachShader(self.gl_program, vertex_shader)
glAttachShader(self.gl_program, fragment_shader)
glLinkProgram(self.gl_program)
glDeleteShader(vertex_shader)
glDeleteShader(fragment_shader)
def projection(self):
scale_matrix = pyrr.matrix44.create_from_scale(Vector3([1, 1, 1]))
rot_matrix = Matrix44.identity()
trans_matrix = pyrr.matrix44.create_from_translation(Vector3([1, 1, 0]))
model_matrix = scale_matrix * rot_matrix * trans_matrix
view_matrix = pyrr.matrix44.create_look_at(numpy.array([4, 3, 3]), numpy.array([1, 1, 0]), numpy.array([0, 1, 0]))
proj_matrix = pyrr.matrix44.create_perspective_projection_matrix(45.0, 1280/720, 0.1, 1000.0)
mvp_matrix = proj_matrix * view_matrix * model_matrix
return mvp_matrix
def display(self):
glEnable(GL_DEPTH_TEST)
glClearColor(0.0, 0.0, 0.0, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glUseProgram(self.gl_program)
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, self.brick_texture)
texture_uniform = glGetUniformLocation(self.gl_program, "the_texture")
glUniform1i(texture_uniform, 0)
trans_uniform = glGetUniformLocation(self.gl_program, "mvp")
glUniformMatrix4fv(trans_uniform, 1, GL_FALSE, self.mvp_matrix)
glBindVertexArray(self.vao)
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, None)
glUseProgram(0)
def main():
pygame.init()
os.environ['SDL_VIDEO_CENTERED'] = '1'
pygame.display.set_caption("3D Graphics")
pygame.display.set_mode((1280, 720), pygame.DOUBLEBUF | pygame.OPENGL)
clock = pygame.time.Clock()
gl = GLProgram()
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
sys.exit()
clock.tick(60)
gl.display()
pygame.display.flip()
if __name__ == "__main__":
main()
顶点着色器：
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec2 text_coord;
out vec2 final_text_coord;
uniform mat4 mvp;
void main()
gl_Position = mvp * vec4(position, 1.0);
final_text_coord = text_coord;
片段着色器：
#version 330 core
in vec2 final_text_coord;
out vec4 frag_color;
uniform sampler2D the_texture;
void main()
frag_color = texture(the_texture, final_text_coord);
【问题讨论】：
pyrr 文档说“矩阵以行优先格式排列”，但您使用它们时就好像它们以列优先格式存储一样。 我理解你对矩阵布局的看法，但是当你说“你使用它们就像它们作为列主要存储一样”时你迷失了，请你详细说明一下。 如果A 是 row-major 并且 B 是相同的矩阵但采用 col-major 格式，则 A = transpose(B)。顺序或矩阵乘法也必须反转。
@18TristonLehmann：您使用glUniformMatrix4fv(..., GL_FALSE) 发送矩阵，按照 GL 的约定，这意味着它需要 16 个浮点数，其中前四个将描述该矩阵的第一列。您也不会通过翻转着色器中的乘法顺序来隐式转置该矩阵，因此您实际应用于这些向量的矩阵将转置为您应该使用的矩阵。
好的，我想我已经成功了，我会尽快发布答案。太感谢了！！！！
【参考方案1】：
您的代码存在几个问题：
矩阵乘法。将两个二维 numpy 数组相乘会产生一个分量乘积，而不是矩阵乘法。使用numpy.matmul 可以解决这个问题。
矩阵约定不明确。
正如pyrr 的文档所述，矩阵在内存中按行优先排列，这与 GL 的默认约定相反。此外，pyrr 创建了转换为标准 GL 约定的矩阵。有人可能认为这两件事都会自行抵消，这只是在一定程度上是正确的。每当您对这些矩阵实际执行一些其他操作（例如乘法）时，它就会中断，然后它将使用本机约定，并搞砸了。
我确实修改了您的代码，提供了两种不同的解决方案。由于您在问题和答案之间稍微更改了代码，因此我最终得到了两个版本的狂野组合。我还禁用了纹理的东西，因为我缺少一些库（和图像文件）。我相应地修改了片段着色器，但这并不重要。
import OpenGL, PIL, pygame, numpy, pyrr, math, sys, os
from OpenGL.GL import *
from PIL import Image
from pyrr import Matrix44, Vector4, Vector3, Quaternion
VERT_DATA = numpy.array([0.5, 0.5, 0.0,
0.5, -0.5, 0.0,
-0.5, -0.5, 0.0,
-0.5, 0.5, 0.0],
dtype="float32")
COLOR_DATA = numpy.array([1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 1.0, 1.0, 1.0],
dtype="float32")
TEXTURE_COORD_DATA = numpy.array([0.5, 0.5,
0.5, -0.5,
-0.5, -0.5,
-0.5, 0.5],
dtype="float32")
INDICES = numpy.array([0, 1, 3,
1, 2, 3],
dtype="int32")
WINDOW_WIDTH=1280
WINDOW_HEIGHT=720
class GLProgram:
def __init__(self):
self.gl_program = glCreateProgram()
self.mvp_matrix = self.projection()
self.shaders()
self.gl_buffers()
self.cube_model_matrix, self.cube_view_matrix, self.cube_proj_matrix = self.gl_translate(Vector3([1.0, 1.0, 1.0]), 45.0, Vector3([0.5, 0.5, 0.5]))
self.cube_mvp = self.gl_translate3(Vector3([1.0, 1.0, 1.0]), -45.0, Vector3([0.5, 0.5, 0.5]))
def gl_texture(self, texture_path):
return 0
def gl_buffers(self):
self.vao = glGenVertexArrays(1)
glBindVertexArray(self.vao)
self.pos_vbo = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.pos_vbo)
glBufferData(GL_ARRAY_BUFFER, VERT_DATA, GL_STATIC_DRAW)
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(0)
self.text_coord_vbo = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.text_coord_vbo)
glBufferData(GL_ARRAY_BUFFER, TEXTURE_COORD_DATA, GL_STATIC_DRAW)
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(1)
self.pos_ebo = glGenBuffers(1)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.pos_ebo)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.pos_ebo)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, INDICES, GL_STATIC_DRAW)
self.brick_texture = self.gl_texture("check.jpg")
def shaders(self):
vertex_shader = glCreateShader(GL_VERTEX_SHADER)
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER)
with open("VertexShader.vert", "r") as vert_file:
vert_source = vert_file.read()
with open("FragmentShader.frag", "r") as frag_file:
frag_source = frag_file.read()
glShaderSource(vertex_shader, vert_source)
glShaderSource(fragment_shader, frag_source)
glCompileShader(vertex_shader)
if not glGetShaderiv(vertex_shader, GL_COMPILE_STATUS):
info_log = glGetShaderInfoLog(vertex_shader)
print ("Compilation Failure for " + vertex_shader + " shader:\n" + info_log)
glCompileShader(fragment_shader)
if not glGetShaderiv(fragment_shader, GL_COMPILE_STATUS):
info_log = glGetShaderInfoLog(fragment_shader)
print ("Compilation Failure for " + fragment_shader + " shader:\n" + info_log)
glAttachShader(self.gl_program, vertex_shader)
glAttachShader(self.gl_program, fragment_shader)
glLinkProgram(self.gl_program)
glDeleteShader(vertex_shader)
glDeleteShader(fragment_shader)
def projection(self):
scale_matrix = pyrr.matrix44.create_from_scale(Vector3([1, 1, 1]))
rot_matrix = Matrix44.identity()
trans_matrix = pyrr.matrix44.create_from_translation(Vector3([1, 1, 0]))
model_matrix = scale_matrix * rot_matrix * trans_matrix
view_matrix = pyrr.matrix44.create_look_at(numpy.array([4, 3, 3]), numpy.array([1, 1, 0]), numpy.array([0, 1, 0]))
proj_matrix = pyrr.matrix44.create_perspective_projection_matrix(45.0, 1280/720, 0.1, 1000.0)
mvp_matrix = proj_matrix * view_matrix * model_matrix
return mvp_matrix
def gl_translate(self, translation, rotation, scale):
trans_matrix = pyrr.matrix44.create_from_translation(translation)
rot_matrix = numpy.transpose(pyrr.matrix44.create_from_y_rotation(rotation))
scale_matrix = numpy.transpose(pyrr.matrix44.create_from_scale(scale))
model_matrix = scale_matrix * rot_matrix * trans_matrix
view_matrix = pyrr.matrix44.create_look_at(numpy.array([2.0, 2.0, 3.0], dtype="float32"),
numpy.array([0.0, 0.0, 0.0], dtype="float32"),
numpy.array([0.0, 1.0, 0.0], dtype="float32"))
proj_matrix = pyrr.matrix44.create_perspective_projection(45.0, WINDOW_WIDTH/WINDOW_HEIGHT, 0.1, 200.0)
return model_matrix, view_matrix, proj_matrix
def gl_translate2(self, translation, rotation, scale):
trans_matrix = pyrr.matrix44.create_from_translation(translation)
rot_matrix = pyrr.matrix44.create_from_y_rotation(rotation)
scale_matrix = pyrr.matrix44.create_from_scale(scale)
model_matrix = numpy.matmul(numpy.matmul(scale_matrix,rot_matrix),trans_matrix)
view_matrix = pyrr.matrix44.create_look_at(numpy.array([2.0, 2.0, 3.0], dtype="float32"),
numpy.array([0.0, 0.0, 0.0], dtype="float32"),
numpy.array([0.0, 1.0, 0.0], dtype="float32"))
proj_matrix = pyrr.matrix44.create_perspective_projection(45.0, WINDOW_WIDTH/WINDOW_HEIGHT, 0.1, 200.0)
m = numpy.matmul(numpy.matmul(model_matrix,view_matrix),proj_matrix)
return m
def gl_translate3(self, translation, rotation, scale):
trans_matrix = numpy.transpose(pyrr.matrix44.create_from_translation(translation))
rot_matrix = numpy.transpose(pyrr.matrix44.create_from_y_rotation(rotation))
scale_matrix = numpy.transpose(pyrr.matrix44.create_from_scale(scale))
model_matrix = numpy.matmul(numpy.matmul(trans_matrix,rot_matrix),scale_matrix)
view_matrix = numpy.transpose(pyrr.matrix44.create_look_at(numpy.array([2.0, 2.0, 3.0], dtype="float32"),
numpy.array([0.0, 0.0, 0.0], dtype="float32"),
numpy.array([0.0, 1.0, 0.0], dtype="float32")))
proj_matrix = numpy.transpose(pyrr.matrix44.create_perspective_projection(45.0, WINDOW_WIDTH/WINDOW_HEIGHT, 0.1, 200.0))
m = numpy.matmul(numpy.matmul(proj_matrix,view_matrix),model_matrix)
return numpy.transpose(m)
def display(self):
glEnable(GL_DEPTH_TEST)
glClearColor(0.0, 0.0, 0.0, 1.0)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glUseProgram(self.gl_program)
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, self.brick_texture)
texture_uniform = glGetUniformLocation(self.gl_program, "the_texture")
glUniform1i(texture_uniform, 0)
trans_uniform = glGetUniformLocation(self.gl_program, "mvp")
glUniformMatrix4fv(trans_uniform, 1, GL_FALSE, self.cube_mvp)
#model_location = glGetUniformLocation(self.gl_program, "model")
#glUniformMatrix4fv(model_location, 1, GL_FALSE, self.cube_model_matrix)
#view_location = glGetUniformLocation(self.gl_program, "view")
#glUniformMatrix4fv(view_location, 1, GL_FALSE, self.cube_view_matrix)
#proj_location = glGetUniformLocation(self.gl_program, "proj")
#glUniformMatrix4fv(proj_location, 1, GL_FALSE, self.cube_proj_matrix)
glBindVertexArray(self.vao)
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, None)
glUseProgram(0)
def main():
pygame.init()
os.environ['SDL_VIDEO_CENTERED'] = '1'
pygame.display.set_caption("3D Graphics")
pygame.display.set_mode((1280, 720), pygame.DOUBLEBUF | pygame.OPENGL)
clock = pygame.time.Clock()
gl = GLProgram()
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
sys.exit()
clock.tick(60)
gl.display()
pygame.display.flip()
if __name__ == "__main__":
main()
使用此顶点着色器：
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec2 text_coord;
out vec2 final_text_coord;
uniform mat4 mvp;
void main()
gl_Position = mvp * vec4(position, 1.0);
final_text_coord = text_coord;
还有这个片段着色器：
#version 330 core
in vec2 final_text_coord;
out vec4 frag_color;
uniform sampler2D the_texture;
void main()
frag_color = vec4(1,0,0,1);
我专门添加了方法gl_translate2和gl_translate3。两者都产生相同的矩阵，2 变体只是使用 pyrr 库的本机乘法顺序约定，gl_translate3 使用 GL 约定。
我还创建了具有不同参数的矩阵
self.cube_mvp = self.gl_translate3(Vector3([1.0, 1.0, 1.0]), -45.0, Vector3([0.5, 0.5, 0.5]))
这在旋转的负号上有所不同（并补偿了您在 gl_transaltion 中所做的额外 transpose）。
结果与您在发布的答案中得到的不同，但这是由于错误的乘法函数（尤其是删除了平移部分并将旋转扭曲为一些剪切操作）。
gl_translate2 和 gl_translate3 得到的结果是：
对于指定的参数，这看起来很合理。
【讨论】：
我不确定gl_translate3 现在与我之前在聊天中提出的变体有何不同，但我们可能错过了一些细节。另请注意，您只需将glUniformMatrix 的transpose 参数设置为GL_TRUE，即可摆脱最后的numpy.transpose(m)。
所以这里的解决方案是始终使用带有 pyrr 矩阵的 numpy.matmul 而不是星号。所以平移、旋转和缩放矩阵也应该使用matmul相乘才能正常工作以上是关于PyOpenGL 透视投影的主要内容，如果未能解决你的问题，请参考以下文章