多重纹理未按预期工作
Multitexturing not working as expected
给定以下代码段：
import os
import textwrap
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from PIL import Image
from OpenGL.GL.ARB.multitexture import *
from OpenGL.extensions import alternate
def get_opengl_info():
return textwrap.dedent("""\
Vendor: {0}
Renderer: {1}
OpenGL Version: {2}
Shader Version: {3}
{4:*^80}
Num Extensions: {5}
{6}
""").format(
glGetString(GL_VENDOR).decode("utf-8"),
glGetString(GL_RENDERER).decode("utf-8"),
glGetString(GL_VERSION).decode("utf-8"),
glGetString(GL_SHADING_LANGUAGE_VERSION).decode("utf-8"),
"OPENGL EXTENSIONS",
glGetIntegerv(GL_NUM_EXTENSIONS),
"\n".join(glGetString(GL_EXTENSIONS).decode("utf-8").split())
)
def create_gl_texture(use_active_texture, channel, width, height, pbits):
id_texture = glGenTextures(1)
if use_active_texture:
glActiveTexture(GL_TEXTURE0 + channel)
glBindTexture(GL_TEXTURE_2D, id_texture)
glPixelStorei(GL_UNPACK_ALIGNMENT, 1)
glTexImage2D(GL_TEXTURE_2D, 0, 3, width, height, 0,
GL_RGBA, GL_UNSIGNED_BYTE, pbits)
glTexParameter(
GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameter(
GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR)
glTexParameter(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameter(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
glGenerateMipmap(GL_TEXTURE_2D)
return id_texture
def load_texture(use_active_texture, filename, i):
image = Image.open(filename)
ix = image.size[0]
iy = image.size[1]
pbits = image.convert("RGBA").tobytes("raw", "RGBA")
id_texture = create_gl_texture(use_active_texture, i, ix, iy, pbits)
print("Loaded", id_texture)
return id_texture
X_AXIS = 0.0
Y_AXIS = 0.0
Z_AXIS = 0.0
DIRECTION = 1
id_textures = []
def init_gl(Width, Height):
global glMultiTexCoord2f, glActiveTexture
print(get_opengl_info())
print("Choosing between: ", glMultiTexCoord2f.__name__,
glMultiTexCoord2fARB.__name__)
print("Choosing between: ", glActiveTexture.__name__,
glActiveTextureARB.__name__)
glMultiTexCoord2f = alternate(
glMultiTexCoord2f,
glMultiTexCoord2fARB
)
glActiveTexture = alternate(
glActiveTexture,
glActiveTextureARB,
)
print("Selected: ", glMultiTexCoord2f.__name__)
print("Selected: ", glActiveTexture.__name__)
if not glMultiTexCoord2f:
print('Multitexture not supported!')
sys.exit(1)
glClearColor(0.0, 0.0, 0.0, 0.0)
glClearDepth(1.0)
glDepthFunc(GL_LESS)
glEnable(GL_DEPTH_TEST)
glShadeModel(GL_SMOOTH)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
gluPerspective(45.0, float(Width) / float(Height), 0.1, 100.0)
glMatrixMode(GL_MODELVIEW)
glEnable(GL_TEXTURE_2D)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL)
def keyPressed(*args):
if args[0] == "3":
sys.exit()
# Method0: Using glBindTexture + glTexCoord2f per face
def draw_method_0():
global X_AXIS, Y_AXIS, Z_AXIS
global DIRECTION
global id_textures
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glLoadIdentity()
glTranslatef(0.0, 0.0, -6.0)
glRotatef(X_AXIS, 1.0, 0.0, 0.0)
glRotatef(Y_AXIS, 0.0, 1.0, 0.0)
glRotatef(Z_AXIS, 0.0, 0.0, 1.0)
glBindTexture(GL_TEXTURE_2D, id_textures[0])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[1])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[2])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[3])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[4])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[5])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glEnd()
X_AXIS = X_AXIS - 0.030
Z_AXIS = Z_AXIS - 0.030
glutSwapBuffers()
# Method1: Using glActiveTexture+glBindTexture+glMultiTexCoord2f per face
def draw_method_1():
global X_AXIS, Y_AXIS, Z_AXIS
global DIRECTION
global id_textures
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glLoadIdentity()
glTranslatef(0.0, 0.0, -6.0)
glRotatef(X_AXIS, 1.0, 0.0, 0.0)
glRotatef(Y_AXIS, 0.0, 1.0, 0.0)
glRotatef(Z_AXIS, 0.0, 0.0, 1.0)
glActiveTexture(GL_TEXTURE0 + 0)
glBindTexture(GL_TEXTURE_2D, id_textures[0])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 0.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 1.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 1.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 0.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 1)
glBindTexture(GL_TEXTURE_2D, id_textures[1])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 1.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 1.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 0.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 0.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 2)
glBindTexture(GL_TEXTURE_2D, id_textures[2])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 0.0, 0.0)
glVertex3f(-1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 1.0, 0.0)
glVertex3f(1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 3)
glBindTexture(GL_TEXTURE_2D, id_textures[3])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 1.0, 1.0)
glVertex3f(-1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 0.0, 1.0)
glVertex3f(1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 4)
glBindTexture(GL_TEXTURE_2D, id_textures[4])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 1.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 0.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 5)
glBindTexture(GL_TEXTURE_2D, id_textures[5])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 0.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 1.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glEnd()
X_AXIS = X_AXIS - 0.030
Z_AXIS = Z_AXIS - 0.030
glutSwapBuffers()
# Method2: Using glActiveTexture+glBindTexture+glTexCoord2f per face
def draw_method_2():
global X_AXIS, Y_AXIS, Z_AXIS
global DIRECTION
global id_textures
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glLoadIdentity()
glTranslatef(0.0, 0.0, -6.0)
glRotatef(X_AXIS, 1.0, 0.0, 0.0)
glRotatef(Y_AXIS, 0.0, 1.0, 0.0)
glRotatef(Z_AXIS, 0.0, 0.0, 1.0)
glActiveTexture(GL_TEXTURE0 + 0)
glBindTexture(GL_TEXTURE_2D, id_textures[0])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 1)
glBindTexture(GL_TEXTURE_2D, id_textures[1])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 2)
glBindTexture(GL_TEXTURE_2D, id_textures[2])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 3)
glBindTexture(GL_TEXTURE_2D, id_textures[3])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 4)
glBindTexture(GL_TEXTURE_2D, id_textures[4])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 5)
glBindTexture(GL_TEXTURE_2D, id_textures[5])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glEnd()
X_AXIS = X_AXIS - 0.030
Z_AXIS = Z_AXIS - 0.030
glutSwapBuffers()
def load_textures(use_active_texture):
global id_textures
id_textures.append(load_texture(use_active_texture, "tex00.jpg", 0))
id_textures.append(load_texture(use_active_texture, "tex01.jpg", 1))
id_textures.append(load_texture(use_active_texture, "tex02.jpg", 2))
id_textures.append(load_texture(use_active_texture, "tex03.jpg", 3))
id_textures.append(load_texture(use_active_texture, "tex04.jpg", 4))
id_textures.append(load_texture(use_active_texture, "tex05.jpg", 5))
def main():
glutInit(sys.argv)
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_ALPHA | GLUT_DEPTH)
glutInitWindowSize(640, 480)
glutInitWindowPosition(200, 200)
glutCreateWindow(b'OpenGL Python Textured Cube')
init_gl(640, 480)
current_method = 2
draw_methods = {
0: {"f": draw_method_0, "use_active_texture": False},
1: {"f": draw_method_1, "use_active_texture": True},
2: {"f": draw_method_2, "use_active_texture": True}
}
draw = draw_methods[current_method]["f"]
load_textures(draw_methods[current_method]["use_active_texture"])
glutDisplayFunc(draw)
glutIdleFunc(draw)
glutKeyboardFunc(keyPressed)
glutMainLoop()
if __name__ == "__main__":
main()
如果我设置 current_method=0 我会得到我期望的输出，所有立方体面都将使用不同的纹理（如预期的那样）：
如果我设置 current_method=1 只有一张脸会被正确纹理化，那是错误的输出：
如果我设置 current_method=2 所有面都将使用相同的纹理 [0]，这也是错误的输出：
我想了解为什么方法 1 和 2 没有提供与方法 0 相同的输出。我知道使用 glActiveTexture 正确使用着色器时变得微不足道，但我想了解在旧的固定管道。
我认为这里的核心问题是对多纹理工作原理的误解。
多纹理同时应用多个纹理到相同的图元。您想要应用不同的纹理，一次一个纹理， 到不同的图元。从这里应该很清楚，多纹理并没有做你想要的，所以没有必要使用它。
多重纹理的工作原理
使用多重纹理，多个纹理单元使用混合混合函数组合它们的结果。
texture unit 0 --> +---------+
| blend | --\
texture unit 1 --> +---------+ \--> +---------+
| blend | --> etc.
texture unit 2 ----------------------> +---------+
每个阶段的混合函数由 glTexEnv 设置，可以是 GL_MODULATE、GL_DECAL 或 GL_ADD。这就是当时光照贴图与纹理结合的方式：一种纹理具有漫反射纹理，一种纹理具有光照贴图纹理。
同样，这与您想要实现的效果完全不同，因此多纹理在您的应用程序中没有意义。
glActiveTexture 的工作原理
glActiveTexture 不会改变绘制到屏幕上的纹理单元。默认情况下，只有纹理单元 #0 会绘制到屏幕上。
glActiveTexture 只允许您将纹理绑定到其他纹理单元。但是，由于未使用纹理单元 #1，因此绑定到单元 #1 的纹理或坐标是什么都无关紧要。所以你应该总是使用 glActiveTexture(GL_TEXTURE0)，因为你总是想改变纹理单元 #0.
解决方案
所以，您有不使用多纹理的工作代码。伟大的！你完成了。您不会因使用更多 OpenGL 功能而获得奖励积分。
或者，如果您使用二维数组纹理，则可以在单个绘制调用中绘制整个立方体。您只需将现有纹理加载为 2D 阵列纹理中的平面，并使用 3D 纹理坐标而不是 2D 纹理坐标。同样，不需要多重纹理。
If i set current_method=1 only one face will be textured properly, that's a wrong output.
不，这不是错误的输出。这是完全正确的输出。您永远不会设置固定功能管道状态来执行任何多纹理处理（有关详细信息，请参阅@Dietrich Epp 的回答）。您的渲染管道配置为：
- 采用每个片段插值顶点颜色的颜色值（你从未设置过，iirc 默认为白色）
- 使用纹理坐标集 0 的每个片段内插纹理坐标对当前绑定到纹理单元 0 的纹理进行采样
- 使用纹理的 Alpha 通道（
GL_DECAL 模式）将结果混合在一起
- 将其用作最终片段颜色。
很明显，您永远不会看到绑定到大于 0 的纹理单元的纹理。那么您看到了什么？
当current_method==0时，您会看到您所期望的。
如果 current_method==1，您会看到 从第一个纹理中提取的单个样本 - 它始终绑定在单元 0 上。由于您没有为单元 0 设置任何 tex 坐标，GL 将只重复最近设置的值，即第一个面的最后一个顶点的 (0,1)。这当然会用于新面的所有顶点，所以插值会产生一个常数值，导致常数纹理采样结果，从而产生常数颜色。
现在 current_method=2 您仍然有第一个纹理绑定在所有面的纹理 0 处。但是由于您现在再次为纹理单元 0 提供了正确的每顶点纹理坐标，因此对其进行采样实际上会再次对不同区域的纹理进行采样，因此您将获得该纹理到基元的合理映射。
给定以下代码段：
import os
import textwrap
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from PIL import Image
from OpenGL.GL.ARB.multitexture import *
from OpenGL.extensions import alternate
def get_opengl_info():
return textwrap.dedent("""\
Vendor: {0}
Renderer: {1}
OpenGL Version: {2}
Shader Version: {3}
{4:*^80}
Num Extensions: {5}
{6}
""").format(
glGetString(GL_VENDOR).decode("utf-8"),
glGetString(GL_RENDERER).decode("utf-8"),
glGetString(GL_VERSION).decode("utf-8"),
glGetString(GL_SHADING_LANGUAGE_VERSION).decode("utf-8"),
"OPENGL EXTENSIONS",
glGetIntegerv(GL_NUM_EXTENSIONS),
"\n".join(glGetString(GL_EXTENSIONS).decode("utf-8").split())
)
def create_gl_texture(use_active_texture, channel, width, height, pbits):
id_texture = glGenTextures(1)
if use_active_texture:
glActiveTexture(GL_TEXTURE0 + channel)
glBindTexture(GL_TEXTURE_2D, id_texture)
glPixelStorei(GL_UNPACK_ALIGNMENT, 1)
glTexImage2D(GL_TEXTURE_2D, 0, 3, width, height, 0,
GL_RGBA, GL_UNSIGNED_BYTE, pbits)
glTexParameter(
GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameter(
GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR)
glTexParameter(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameter(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
glGenerateMipmap(GL_TEXTURE_2D)
return id_texture
def load_texture(use_active_texture, filename, i):
image = Image.open(filename)
ix = image.size[0]
iy = image.size[1]
pbits = image.convert("RGBA").tobytes("raw", "RGBA")
id_texture = create_gl_texture(use_active_texture, i, ix, iy, pbits)
print("Loaded", id_texture)
return id_texture
X_AXIS = 0.0
Y_AXIS = 0.0
Z_AXIS = 0.0
DIRECTION = 1
id_textures = []
def init_gl(Width, Height):
global glMultiTexCoord2f, glActiveTexture
print(get_opengl_info())
print("Choosing between: ", glMultiTexCoord2f.__name__,
glMultiTexCoord2fARB.__name__)
print("Choosing between: ", glActiveTexture.__name__,
glActiveTextureARB.__name__)
glMultiTexCoord2f = alternate(
glMultiTexCoord2f,
glMultiTexCoord2fARB
)
glActiveTexture = alternate(
glActiveTexture,
glActiveTextureARB,
)
print("Selected: ", glMultiTexCoord2f.__name__)
print("Selected: ", glActiveTexture.__name__)
if not glMultiTexCoord2f:
print('Multitexture not supported!')
sys.exit(1)
glClearColor(0.0, 0.0, 0.0, 0.0)
glClearDepth(1.0)
glDepthFunc(GL_LESS)
glEnable(GL_DEPTH_TEST)
glShadeModel(GL_SMOOTH)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
gluPerspective(45.0, float(Width) / float(Height), 0.1, 100.0)
glMatrixMode(GL_MODELVIEW)
glEnable(GL_TEXTURE_2D)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL)
def keyPressed(*args):
if args[0] == "3":
sys.exit()
# Method0: Using glBindTexture + glTexCoord2f per face
def draw_method_0():
global X_AXIS, Y_AXIS, Z_AXIS
global DIRECTION
global id_textures
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glLoadIdentity()
glTranslatef(0.0, 0.0, -6.0)
glRotatef(X_AXIS, 1.0, 0.0, 0.0)
glRotatef(Y_AXIS, 0.0, 1.0, 0.0)
glRotatef(Z_AXIS, 0.0, 0.0, 1.0)
glBindTexture(GL_TEXTURE_2D, id_textures[0])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[1])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[2])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[3])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[4])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glEnd()
glBindTexture(GL_TEXTURE_2D, id_textures[5])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glEnd()
X_AXIS = X_AXIS - 0.030
Z_AXIS = Z_AXIS - 0.030
glutSwapBuffers()
# Method1: Using glActiveTexture+glBindTexture+glMultiTexCoord2f per face
def draw_method_1():
global X_AXIS, Y_AXIS, Z_AXIS
global DIRECTION
global id_textures
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glLoadIdentity()
glTranslatef(0.0, 0.0, -6.0)
glRotatef(X_AXIS, 1.0, 0.0, 0.0)
glRotatef(Y_AXIS, 0.0, 1.0, 0.0)
glRotatef(Z_AXIS, 0.0, 0.0, 1.0)
glActiveTexture(GL_TEXTURE0 + 0)
glBindTexture(GL_TEXTURE_2D, id_textures[0])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 0.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 1.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 1.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 0, 0.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 1)
glBindTexture(GL_TEXTURE_2D, id_textures[1])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 1.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 1.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 0.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 1, 0.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 2)
glBindTexture(GL_TEXTURE_2D, id_textures[2])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 0.0, 0.0)
glVertex3f(-1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 1.0, 0.0)
glVertex3f(1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 2, 1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 3)
glBindTexture(GL_TEXTURE_2D, id_textures[3])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 1.0, 1.0)
glVertex3f(-1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 0.0, 1.0)
glVertex3f(1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 3, 1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 4)
glBindTexture(GL_TEXTURE_2D, id_textures[4])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 1.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 0.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 4, 0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 5)
glBindTexture(GL_TEXTURE_2D, id_textures[5])
glBegin(GL_QUADS)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 0.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 1.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glMultiTexCoord2f(GL_TEXTURE0 + 5, 0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glEnd()
X_AXIS = X_AXIS - 0.030
Z_AXIS = Z_AXIS - 0.030
glutSwapBuffers()
# Method2: Using glActiveTexture+glBindTexture+glTexCoord2f per face
def draw_method_2():
global X_AXIS, Y_AXIS, Z_AXIS
global DIRECTION
global id_textures
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glLoadIdentity()
glTranslatef(0.0, 0.0, -6.0)
glRotatef(X_AXIS, 1.0, 0.0, 0.0)
glRotatef(Y_AXIS, 0.0, 1.0, 0.0)
glRotatef(Z_AXIS, 0.0, 0.0, 1.0)
glActiveTexture(GL_TEXTURE0 + 0)
glBindTexture(GL_TEXTURE_2D, id_textures[0])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 1)
glBindTexture(GL_TEXTURE_2D, id_textures[1])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 2)
glBindTexture(GL_TEXTURE_2D, id_textures[2])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 3)
glBindTexture(GL_TEXTURE_2D, id_textures[3])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 4)
glBindTexture(GL_TEXTURE_2D, id_textures[4])
glBegin(GL_QUADS)
glTexCoord2f(1.0, 0.0)
glVertex3f(1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(1.0, 1.0, 1.0)
glTexCoord2f(0.0, 0.0)
glVertex3f(1.0, -1.0, 1.0)
glEnd()
glActiveTexture(GL_TEXTURE0 + 5)
glBindTexture(GL_TEXTURE_2D, id_textures[5])
glBegin(GL_QUADS)
glTexCoord2f(0.0, 0.0)
glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 0.0)
glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0)
glVertex3f(-1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0)
glVertex3f(-1.0, 1.0, -1.0)
glEnd()
X_AXIS = X_AXIS - 0.030
Z_AXIS = Z_AXIS - 0.030
glutSwapBuffers()
def load_textures(use_active_texture):
global id_textures
id_textures.append(load_texture(use_active_texture, "tex00.jpg", 0))
id_textures.append(load_texture(use_active_texture, "tex01.jpg", 1))
id_textures.append(load_texture(use_active_texture, "tex02.jpg", 2))
id_textures.append(load_texture(use_active_texture, "tex03.jpg", 3))
id_textures.append(load_texture(use_active_texture, "tex04.jpg", 4))
id_textures.append(load_texture(use_active_texture, "tex05.jpg", 5))
def main():
glutInit(sys.argv)
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_ALPHA | GLUT_DEPTH)
glutInitWindowSize(640, 480)
glutInitWindowPosition(200, 200)
glutCreateWindow(b'OpenGL Python Textured Cube')
init_gl(640, 480)
current_method = 2
draw_methods = {
0: {"f": draw_method_0, "use_active_texture": False},
1: {"f": draw_method_1, "use_active_texture": True},
2: {"f": draw_method_2, "use_active_texture": True}
}
draw = draw_methods[current_method]["f"]
load_textures(draw_methods[current_method]["use_active_texture"])
glutDisplayFunc(draw)
glutIdleFunc(draw)
glutKeyboardFunc(keyPressed)
glutMainLoop()
if __name__ == "__main__":
main()
如果我设置 current_method=0 我会得到我期望的输出，所有立方体面都将使用不同的纹理（如预期的那样）：
如果我设置 current_method=1 只有一张脸会被正确纹理化，那是错误的输出：
如果我设置 current_method=2 所有面都将使用相同的纹理 [0]，这也是错误的输出：
我想了解为什么方法 1 和 2 没有提供与方法 0 相同的输出。我知道使用 glActiveTexture 正确使用着色器时变得微不足道，但我想了解在旧的固定管道。
我认为这里的核心问题是对多纹理工作原理的误解。
多纹理同时应用多个纹理到相同的图元。您想要应用不同的纹理，一次一个纹理， 到不同的图元。从这里应该很清楚，多纹理并没有做你想要的，所以没有必要使用它。
多重纹理的工作原理
使用多重纹理，多个纹理单元使用混合混合函数组合它们的结果。
texture unit 0 --> +---------+
| blend | --\
texture unit 1 --> +---------+ \--> +---------+
| blend | --> etc.
texture unit 2 ----------------------> +---------+
每个阶段的混合函数由 glTexEnv 设置，可以是 GL_MODULATE、GL_DECAL 或 GL_ADD。这就是当时光照贴图与纹理结合的方式：一种纹理具有漫反射纹理，一种纹理具有光照贴图纹理。
同样，这与您想要实现的效果完全不同，因此多纹理在您的应用程序中没有意义。
glActiveTexture 的工作原理
glActiveTexture 不会改变绘制到屏幕上的纹理单元。默认情况下，只有纹理单元 #0 会绘制到屏幕上。
glActiveTexture 只允许您将纹理绑定到其他纹理单元。但是，由于未使用纹理单元 #1，因此绑定到单元 #1 的纹理或坐标是什么都无关紧要。所以你应该总是使用 glActiveTexture(GL_TEXTURE0)，因为你总是想改变纹理单元 #0.
解决方案
所以，您有不使用多纹理的工作代码。伟大的！你完成了。您不会因使用更多 OpenGL 功能而获得奖励积分。
或者，如果您使用二维数组纹理，则可以在单个绘制调用中绘制整个立方体。您只需将现有纹理加载为 2D 阵列纹理中的平面，并使用 3D 纹理坐标而不是 2D 纹理坐标。同样，不需要多重纹理。
If i set
current_method=1only one face will be textured properly, that's a wrong output.
不，这不是错误的输出。这是完全正确的输出。您永远不会设置固定功能管道状态来执行任何多纹理处理（有关详细信息，请参阅@Dietrich Epp 的回答）。您的渲染管道配置为：
- 采用每个片段插值顶点颜色的颜色值（你从未设置过，iirc 默认为白色）
- 使用纹理坐标集 0 的每个片段内插纹理坐标对当前绑定到纹理单元 0 的纹理进行采样
- 使用纹理的 Alpha 通道（
GL_DECAL模式）将结果混合在一起 - 将其用作最终片段颜色。
很明显，您永远不会看到绑定到大于 0 的纹理单元的纹理。那么您看到了什么？
当current_method==0时，您会看到您所期望的。
如果 current_method==1，您会看到 从第一个纹理中提取的单个样本 - 它始终绑定在单元 0 上。由于您没有为单元 0 设置任何 tex 坐标，GL 将只重复最近设置的值，即第一个面的最后一个顶点的 (0,1)。这当然会用于新面的所有顶点，所以插值会产生一个常数值，导致常数纹理采样结果，从而产生常数颜色。
现在 current_method=2 您仍然有第一个纹理绑定在所有面的纹理 0 处。但是由于您现在再次为纹理单元 0 提供了正确的每顶点纹理坐标，因此对其进行采样实际上会再次对不同区域的纹理进行采样，因此您将获得该纹理到基元的合理映射。