Python之OpenGL笔记(16)：旋转的光照钢边木箱
一、目的
1、光照下的钢边木箱，学习光照基础、材质及光照贴图。
二、程序运行结果
三、光照基础
1、环境光照(Ambient Lighting)：
即使在黑暗的情况下，世界上也仍然有一些光亮(月亮、一个来自远处的光)，所以物体永远不会是完全黑暗的。我们使用环境光照来模拟这种情况，也就是无论如何永远都给物体一些颜色。
把环境光照添加到场景里非常简单。我们用光的颜色乘以一个(数值)很小常量环境因子，再乘以物体的颜色，然后使用它作为片段的颜色。
2、漫反射光照(Diffuse Lighting)：
模拟一个发光物对物体的方向性影响(Directional Impact)。它是冯氏光照模型最显著的组成部分。面向光源的一面比其他面会更亮。
计算漫反射光照需要法向量（一个垂直于顶点表面的向量）和定向的光线（作为光的位置和片段的位置之间的向量差的方向向量。为了计算这个光线，我们需要光的位置向量和片段的位置向量。）两向量向量进行点乘，来计算光对当前片段的实际的散射影响。结果值再乘以光的颜色，得到散射因子。
3、镜面光照(Specular Lighting)：
模拟有光泽物体上面出现的亮点。镜面光照的颜色，相比于物体的颜色更倾向于光的颜色。先计算视线方向与反射方向的点乘(确保它不是负值)，然后得到它的32次幂。这个32是高光的发光值(Shininess)。一个物体的发光值越高，反射光的能力越强，散射得越少，高光点越小。
四、材质
当描述物体的时候，我们可以这样定义一个材质；ambient材质向量定义了在环境光照下这个物体反射的是什么颜色；通常这是和物体颜色相同的颜色。diffuse材质向量定义了在漫反射光照下物体的颜色。漫反射颜色被设置为(和环境光照一样)我们需要的物体颜色。specular材质向量设置的是物体受到的镜面光照的影响的颜色(或者可能是反射一个物体特定的镜面高光颜色)。最后，shininess影响镜面高光的散射/半径。
五、源代码
"""
glfw_cube05.py
Author: dalong10
Description: Draw 4 Cube, learning OPENGL
"""
import glutils #Common OpenGL utilities,see glutils.py
import sys, random, math
import OpenGL
from OpenGL.GL import *
from OpenGL.GL.shaders import *
import numpy
import numpy as np
import glfw
strVS = """
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 normal;
layout (location = 2) in vec2 texCoords;
out vec3 Normal;
out vec3 FragPos;
out vec2 TexCoords;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
void main()
{
gl_Position = uPMatrix * uMVMatrix * vec4(position, 1.0f);
FragPos = vec3(uMVMatrix * vec4(position, 1.0f));
Normal = mat3(transpose(inverse(uMVMatrix))) * normal;
TexCoords = texCoords;
}
"""
strFS = """
#version 330 core
struct Material {
sampler2D diffuse;
sampler2D specular;
float shininess;
};
struct Light {
vec3 position;
vec3 ambient;
vec3 diffuse;
vec3 specular;
};
in vec3 FragPos;
in vec3 Normal;
in vec2 TexCoords;
out vec4 color;
uniform vec3 viewPos;
uniform Material material;
uniform Light light;
void main()
{
// Ambient
vec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoords));
// Diffuse
vec3 norm = normalize(Normal);
vec3 lightDir = normalize(light.position - FragPos);
float diff = max(dot(norm, lightDir), 0.0);
vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoords));
// Specular
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir, norm);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));
color = vec4(ambient + diffuse + specular, 1.0f);
}
"""
class FirstCube:
def __init__(self, side):
self.side = side
# load shaders
self.program = glutils.loadShaders(strVS, strFS)
glUseProgram(self.program)
# attributes
self.vertIndex = glGetAttribLocation(self.program, b"position")
self.norIndex = glGetAttribLocation(self.program, b"normal")
self.texIndex = glGetAttribLocation(self.program, b"texCoords")
lightPos=[1.2,1.0,2.0]
s = side/2.0
cube_vertices = [
-s, -s, -s,
s, -s, -s,
s, s, -s,
s, s, -s,
-s, s, -s,
-s, -s, -s,
-s, -s, s,
s, -s, s,
s, s, s,
s, s, s,
-s, s, s,
-s, -s, s,
-s, s, s,
-s, s, -s,
-s, -s, -s,
-s, -s, -s,
-s, -s, s,
-s, s, s,
s, s, s,
s, s, -s,
s, -s, -s,
s, -s, -s,
s, -s, s,
s, s, s,
-s, -s, -s,
s, -s, -s,
s, -s, s,
s, -s, s,
-s, -s, s,
-s, -s, -s,
-s, s, -s,
s, s,-s,
s, s, s,
s, s, s,
-s, s, s,
-s, s,-s
]
# Normals
t=1.0
cube_normals=[
0,0,-t, 0,0,-t, 0,0,-t, 0,0,-t, 0,0,-t, 0,0,-t,
0,0,t, 0,0, t, 0,0, t, 0,0, t, 0,0, t, 0,0, t,
-t,0,0, -t,0,0, -t,0,0, -t,0,0, -t,0,0, -t,0,0,
t,0,0, t,0,0, t,0,0, t,0,0, t,0,0, t,0,0,
0,-t,0, 0,-t,0, 0,-t,0, 0,-t,0, 0,-t,0, 0,-t,0,
0,t,0, 0,t,0, 0,t,0, 0,t,0, 0,t,0, 0,t,0
]
# texture coords
quadT = [
0,0, t,0, t,t, t,t, 0,t, 0,0,
0,0, t,0, t,t, t,t, 0,t, 0,0,
t,0, t,t, 0,t, 0,t, 0,0, t,0,
t,0, t,t, 0,t, 0,t, 0,0, t,0,
0,t, t,t, t,0, t,0, 0,0, 0,t,
0,t, t,t, t,0, t,0, 0,0, 0,t
]
# set up vertex array object (VAO)
self.vao = glGenVertexArrays(1)
glBindVertexArray(self.vao)
# set up VBOs
vertexData = numpy.array(cube_vertices, numpy.float32)
self.vertexBuffer = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer)
glBufferData(GL_ARRAY_BUFFER, 4*len(vertexData), vertexData, GL_STATIC_DRAW)
noData = numpy.array(cube_normals, numpy.float32)
self.normalsBuffer = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.normalsBuffer)
glBufferData(GL_ARRAY_BUFFER, 4*len(noData), noData,GL_STATIC_DRAW)
tcData = numpy.array(quadT, numpy.float32)
self.tcBuffer = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self.tcBuffer)
glBufferData(GL_ARRAY_BUFFER, 4*len(tcData), tcData,GL_STATIC_DRAW)
# enable arrays
glEnableVertexAttribArray(self.vertIndex)
glEnableVertexAttribArray(self.norIndex)
glEnableVertexAttribArray(self.texIndex)
# Position attribute
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer)
glVertexAttribPointer(self.vertIndex, 3, GL_FLOAT, GL_FALSE, 0,None)
# Normals attribute
glBindBuffer(GL_ARRAY_BUFFER, self.normalsBuffer)
glVertexAttribPointer(self.norIndex, 3, GL_FLOAT, GL_FALSE, 0,None)
# TexCoord attribute
glBindBuffer(GL_ARRAY_BUFFER, self.tcBuffer)
glVertexAttribPointer(self.texIndex, 2, GL_FLOAT, GL_FALSE, 0,None)
# unbind VAO
glBindVertexArray(0)
glBindBuffer(GL_ARRAY_BUFFER, 0)
def render(self,pMatrix,mvMatrix,texid,texid2,a,b,c,scale,r):
self.texid = texid
self.texid2 = texid2
# enable texture
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, self.texid)
glActiveTexture(GL_TEXTURE1)
glBindTexture(GL_TEXTURE_2D, self.texid2)
# use shader
glUseProgram(self.program)
glUniformMatrix4fv(glGetUniformLocation(self.program, 'uPMatrix'),
1, GL_FALSE, pMatrix)
# set modelview matrix
glUniformMatrix4fv(glGetUniformLocation(self.program, 'uMVMatrix'),
1, GL_FALSE, mvMatrix)
glUniform1i(glGetUniformLocation(self.program, "material.diffuse"), 0)
glUniform1i(glGetUniformLocation(self.program, "material.specular"), 1)
lightPosLoc = glGetUniformLocation(self.program, "light.position")
glUniform3f(lightPosLoc, 1.2, 1.0, 2.0)
# Set lights properties
glUniform3f(glGetUniformLocation(self.program, "light.ambient"), 0.2, 0.2, 0.2)
glUniform3f(glGetUniformLocation(self.program, "light.diffuse"), 0.5, 0.5, 0.5)
glUniform3f(glGetUniformLocation(self.program, "light.specular"), 1.0, 1.0, 1.0)
# Set material properties
glUniform1f(glGetUniformLocation(self.program, "material.shininess"), 32.0)
# bind VAO
glBindVertexArray(self.vao)
glEnable(GL_DEPTH_TEST)
# draw
glDrawArrays(GL_TRIANGLES, 0, 36)
# unbind VAO
glBindVertexArray(0)
if __name__ == '__main__':
import sys
import glfw
import OpenGL.GL as gl
camera = glutils.Camera([0.0, 0.0, 3.0],
[0.0, 0.0, 0.0],
[0.0, 1.0, 0.0])
def on_key(window, key, scancode, action, mods):
if key == glfw.KEY_ESCAPE and action == glfw.PRESS:
glfw.set_window_should_close(window,1)
# Initialize the library
if not glfw.init():
sys.exit()
# Create a windowed mode window and its OpenGL context
window = glfw.create_window(300, 300, "draw Light Cube ", None, None)
if not window:
glfw.terminate()
sys.exit()
# Make the window's context current
glfw.make_context_current(window)
# Install a key handler
glfw.set_key_callback(window, on_key)
PI = 3.14159265358979323846264
texid = glutils.loadTexture("container2.png")
texid2 = glutils.loadTexture("container2_specular.png")
# Loop until the user closes the window
a=0
firstCube0 = FirstCube(1.0)
while not glfw.window_should_close(window):
# Render here
width, height = glfw.get_framebuffer_size(window)
ratio = width / float(height)
gl.glViewport(0, 0, width, height)
gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
gl.glMatrixMode(gl.GL_PROJECTION)
gl.glLoadIdentity()
gl.glOrtho(-ratio, ratio, -1, 1, 1, -1)
gl.glMatrixMode(gl.GL_MODELVIEW)
gl.glLoadIdentity()
gl.glClearColor(0.0,0.0,4.0,0.0)
camera.eye=[5*math.sin(a*PI/180.0),0,5*math.cos(a*PI/180.0)]
pMatrix = glutils.perspective(100.0, ratio, 0.1, 100.0)
# modelview matrix
mvMatrix = glutils.lookAt(camera.eye, camera.center, camera.up)
glBindTexture(GL_TEXTURE_2D, texid)
i=a
firstCube0.render(pMatrix, mvMatrix,texid,texid2,1.2,1.0,2.0 ,0.5,i)
a=a+1
if a>360:
a=0
# Swap front and back buffers
glfw.swap_buffers(window)
# Poll for and process events
glfw.poll_events()
glfw.terminate()
六、参考文献
1、learnopengl教程 https://learnopengl-cn.readthedocs.io/zh/latest/02%20Lighting/04%20Lighting%20maps/
2、大龙10简书 https://www.jianshu.com/p/4382b25ad797
3、贴图地址： https://learnopengl.com/img/textures/container2.png，
https://learnopengl.com/img/textures/container2_specular.png