在模型上放置纹理并在 OGL 4.0 GLSL 中使用纹理矩阵
一个简单的 OGL 4.0 GLSL 着色器程序，显示如何在网格上映射 2D 纹理。该程序使用 phyton 脚本执行。要运行脚本，必须安装 PyOpenGL 和 NumPy。
纹理矩阵定义纹理在网格上的映射方式。通过操作纹理矩阵，可以移动，缩放和旋转纹理。
顶点着色器
tex.vert
#version 400
layout (location = 0) in vec3 inPos;
layout (location = 1) in vec2 inTex;
out vec2 vertTex;
uniform mat4 u_projectionMat44;
uniform mat4 u_viewMat44;
uniform mat4 u_modelMat44;
uniform mat4 u_textureMat44;
void main()
{
vertTex = ( u_textureMat44 * vec4( inTex, 0.0, 1.0 ) ).st;
vec4 modolPos = u_modelMat44 * vec4( inPos, 1.0 );
vec4 viewPos = u_viewMat44 * modolPos;
gl_Position = u_projectionMat44 * viewPos;
}
片段着色器
tex.frag
#version 400
in vec2 vertTex;
out vec4 fragColor;
uniform sampler2D u_texture;
void main()
{
vec4 texCol = texture( u_texture, vertTex.st );
fragColor = vec4( texCol.rgb, 1.0 );
}
Phyton 剧本
from OpenGL.GL import *
from OpenGL.GLUT import *
from OpenGL.GLU import *
import numpy as np
from time import time
import math
import sys
# draw event
def OnDraw():
currentTime = time()
# set up projection matrix
prjMat = perspective( 90.0, wndW/wndH, 0.5, 100.0)
# set up view matrix
viewMat = Translate( np.matrix(np.identity(4), copy=False, dtype='float32'), np.array( [0.0, 0.0, -15.0] ) )
viewMat = RotateView( viewMat, [30.0, CalcAng( currentTime, 60.0 ), 0.0] )
# set up tetrahedron model matrix
cubeModelMat = np.matrix(np.identity(4), copy=False, dtype='float32')
cubeModelMat = RotateX( cubeModelMat, -90.0 )
cubeModelMat = Scale( cubeModelMat, np.repeat( 5.0, 3 ) )
# set up texture matrix
texMat = np.matrix(np.identity(4), copy=False, dtype='float32')
deltaT = Fract( (currentTime - startTime) / 28.0 ) * 28.0
if deltaT < 7.0 or deltaT >= 21.0:
texMat = Scale( texMat, np.repeat( CalcMove(currentTime, 7.0, [1.0, 2.0]), 3 ) )
if deltaT >= 7.0 and deltaT < 14.0 or deltaT >= 21.0:
transAng = math.radians( CalcAng(currentTime, 7.0) )
texMat = Translate( texMat, np.array( [math.sin(transAng)*0.5, math.cos(transAng)*0.5-0.5, 0.0] ) )
if deltaT >= 14.0:
texMat = RotateZ( texMat, CalcAng(currentTime, 7.0) )
# set up attributes and shader program
glEnable( GL_DEPTH_TEST )
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT )
glUseProgram( shaderProgram )
glUniformMatrix4fv( projectionMatLocation, 1, GL_FALSE, prjMat )
glUniformMatrix4fv( viewMatLocation, 1, GL_FALSE, viewMat )
glUniformMatrix4fv( textureMatLocation, 1, GL_FALSE, texMat )
glUniform1i( textureLocation, 0 )
# draw cube
glUniformMatrix4fv( modelMatLocation, 1, GL_FALSE, cubeModelMat )
glBindVertexArray( cubeVAObj )
glDrawElements(GL_TRIANGLES, len(cubeIndices), GL_UNSIGNED_INT, cubeIndices)
glutSwapBuffers()
def Fract(val): return val - math.trunc(val)
def CalcAng(currentTime, intervall): return Fract( (currentTime - startTime) / intervall ) * 360.0
def CalcMove(currentTime, intervall, range):
pos = Fract( (currentTime - startTime) / intervall ) * 2.0
pos = pos if pos < 1.0 else (2.0-pos)
return range[0] + (range[1] - range[0]) * pos
# read shader program and compile shader
def CompileShader( sourceFileName, shaderStage ):
with open( sourceFileName, 'r' ) as sourceFile:
sourceCode = sourceFile.read()
nameMap = { GL_VERTEX_SHADER: 'vertex', GL_FRAGMENT_SHADER: 'fragment' }
print( '\n%s shader code:' % nameMap.get(shaderStage, '') )
print( sourceCode )
shaderObj = glCreateShader( shaderStage )
glShaderSource( shaderObj, sourceCode )
glCompileShader( shaderObj )
result = glGetShaderiv( shaderObj, GL_COMPILE_STATUS )
if not (result):
print( glGetShaderInfoLog( shaderObj ) )
sys.exit()
return shaderObj
# linke shader objects to shader program
def LinkProgram( shaderObjs ):
shaderProgram = glCreateProgram()
for shObj in shaderObjs:
glAttachShader( shaderProgram, shObj )
glLinkProgram( shaderProgram )
result = glGetProgramiv( shaderProgram, GL_LINK_STATUS )
if not (result):
print( 'link error:' )
print( glGetProgramInfoLog( shaderProgram ) )
sys.exit()
return shaderProgram
# create vertex array object
def CreateVAO( dataArrays ):
noOfBuffers = len(dataArrays)
buffers = glGenBuffers(noOfBuffers)
newVAObj = glGenVertexArrays( 1 )
glBindVertexArray( newVAObj )
for inx in range(0, noOfBuffers):
vertexSize, dataArr = dataArrays[inx]
arr = np.array( dataArr, dtype='float32' )
glBindBuffer( GL_ARRAY_BUFFER, buffers[inx] )
glBufferData( GL_ARRAY_BUFFER, arr, GL_STATIC_DRAW )
glEnableVertexAttribArray( inx )
glVertexAttribPointer( inx, vertexSize, GL_FLOAT, GL_FALSE, 0, None )
return newVAObj
def Translate(matA, trans):
matB = np.copy(matA)
for i in range(0, 4): matB[3,i] = matA[0,i] * trans[0] + matA[1,i] * trans[1] + matA[2,i] * trans[2] + matA[3,i]
return matB
def Scale(matA, s):
matB = np.copy(matA)
for i0 in range(0, 3):
for i1 in range(0, 4): matB[i0,i1] = matA[i0,i1] * s[i0]
return matB
def RotateHlp(matA, angDeg, a0, a1):
matB = np.copy(matA)
ang = math.radians(angDeg)
sinAng, cosAng = math.sin(ang), math.cos(ang)
for i in range(0, 4):
matB[a0,i] = matA[a0,i] * cosAng + matA[a1,i] * sinAng
matB[a1,i] = matA[a0,i] * -sinAng + matA[a1,i] * cosAng
return matB
def RotateX(matA, angDeg): return RotateHlp(matA, angDeg, 1, 2)
def RotateY(matA, angDeg): return RotateHlp(matA, angDeg, 2, 0)
def RotateZ(matA, angDeg): return RotateHlp(matA, angDeg, 0, 1)
def RotateView(matA, angDeg): return RotateZ(RotateY(RotateX(matA, angDeg[0]), angDeg[1]), angDeg[2])
def perspective(fov, aspectRatio, near, far):
fn, f_n = far + near, far - near
r, t = aspectRatio, 1.0 / math.tan( math.radians(fov) / 2.0 )
return np.matrix( [ [t/r,0,0,0], [0,t,0,0], [0,0,-fn/f_n,-2.0*far*near/f_n], [0,0,-1,0] ] )
# initialize glut
glutInit()
# create window
wndW, wndH = 800, 600
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_ALPHA | GLUT_DEPTH)
glutInitWindowPosition(0, 0)
glutInitWindowSize(wndW, wndH)
wndID = glutCreateWindow(b'OGL window')
glutDisplayFunc(OnDraw)
glutIdleFunc(OnDraw)
# define cube vertex array opject
icoPts = [
[-1.0, -1.0, 1.0], [ 1.0, -1.0, 1.0], [ 1.0, 1.0, 1.0], [-1.0, 1.0, 1.0],
[-1.0, -1.0, -1.0], [ 1.0, -1.0, -1.0], [ 1.0, 1.0, -1.0], [-1.0, 1.0, -1.0] ]
cubePosData = []
for inx in [ 0, 1, 2, 3, 1, 5, 6, 2, 5, 4, 7, 6, 4, 0, 3, 7, 3, 2, 6, 7, 1, 0, 4, 5 ]:
for inx_s in range(0, 3): cubePosData.append( icoPts[inx][inx_s] )
cubeTexData = []
for inx in range(0, 6):
for texCoord in [-0.5, -0.5, 0.5, -0.5, 0.5, 0.5, -0.5, 0.5]: cubeTexData.append( texCoord )
icoCol = [ [1.0, 0.0, 0.0], [1.0, 0.5, 0.0], [1.0, 0.0, 1.0], [1.0, 1.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0] ]
cubeIndices = []
for inx in range(0, 6):
for inx_s in [0, 1, 2, 0, 2, 3]: cubeIndices.append( inx * 4 + inx_s )
cubeVAObj = CreateVAO( [ (3, cubePosData), (2, cubeTexData) ] )
cubeInxArr = np.array( cubeIndices, dtype='uint' )
# load, compile and link shader
shaderProgram = LinkProgram( [
CompileShader( 'python/ogl4tex/tex.vert', GL_VERTEX_SHADER ),
CompileShader( 'python/ogl4tex/tex.frag', GL_FRAGMENT_SHADER )
] )
projectionMatLocation = glGetUniformLocation(shaderProgram, "u_projectionMat44")
viewMatLocation = glGetUniformLocation(shaderProgram, "u_viewMat44")
modelMatLocation = glGetUniformLocation(shaderProgram, "u_modelMat44")
textureMatLocation = glGetUniformLocation(shaderProgram, "u_textureMat44")
textureLocation = glGetUniformLocation(shaderProgram, "u_texture")
# create texture
texCX, texCY = 128, 128
texPlan = np.zeros( texCX * texCY * 4, dtype=np.uint8 )
for inx_x in range(0, texCX):
for inx_y in range(0, texCY):
val_x = math.sin( math.pi * 6.0 * inx_x / texCX )
val_y = math.sin( math.pi * 6.0 * inx_y / texCY )
inx_tex = inx_y * texCX * 4 + inx_x * 4
texPlan[inx_tex + 0] = int( 128 + 127 * val_x )
texPlan[inx_tex + 1] = 63
texPlan[inx_tex + 2] = int( 128 + 127 * val_y )
texPlan[inx_tex + 3] = 255
glActiveTexture( GL_TEXTURE0 )
texObj = glGenTextures( 1 )
glBindTexture( GL_TEXTURE_2D, texObj )
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texCX, texCY, 0, GL_RGBA, GL_UNSIGNED_BYTE, texPlan)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
# start main loop
startTime = time()
glutMainLoop()