[英]Texture Loading using PNGDecoder and LWJGL
I am relatively new to OpenGL, so this question might seem a bit trivial.我对 OpenGL 比较陌生,所以这个问题可能看起来有点微不足道。 I have this code in my Main.java, which is supposed to output a rectangle with the texture of the image on it:我的 Main.java 中有这个代码,它应该输出一个带有图像纹理的矩形:
float vertices[] = {
// positions // colors // texture coords
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom left
-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // top left
};
int indices[] = {
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
int VBO = glGenBuffers(), VAO = glGenVertexArrays(), EBO = glGenBuffers();
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices, GL_STATIC_DRAW);
// position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, false, 8, 0);
glEnableVertexAttribArray(0);
// color attribute
glVertexAttribPointer(1, 3, GL_FLOAT, false, 8, 2);
glEnableVertexAttribArray(1);
// texture coord attribute
glVertexAttribPointer(2, 2, GL_FLOAT, false, 8, 5);
glEnableVertexAttribArray(2);
Texture texture = null;
try {
log.info("Loading texture");
texture = Texture.loadTexture("texture.png");
} catch (IOException e) {
log.severe("Texture loading failed due to IOException: " + e.getMessage());
e.printStackTrace();
}
while (!glfwWindowShouldClose(window))
{
glClear(GL_COLOR_BUFFER_BIT);
if(mainProgram != null) {
mainProgram.use();
}
glBindTexture(GL_TEXTURE_2D, texture.getId());
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
//...
}
My shaders are the following: Vertex Shader:我的着色器如下: 顶点着色器:
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout(location = 2) in vec2 aTexCoord;
out vec3 vertexColor;
out vec2 texCoord;
void main()
{
gl_Position = vec4(aPos , 1.0);
vertexColor = aColor;
texCoord = aTexCoord;
}
Fragment Shader:片段着色器:
#version 330 core
out vec4 FragColor;
in vec3 ourColor;
in vec2 TexCoord;
// texture sampler
uniform sampler2D texture1;
void main()
{
FragColor = texture(texture1, TexCoord);
}
The Texture class referenced above is the following:上面引用的 Texture 类如下:
public class Texture {
public static Texture loadTexture(String fileName) throws IOException{
//load png file
PNGDecoder decoder = new PNGDecoder(new java.io.FileInputStream(new File("C:/Users/Using/Absolute/Paths/For/Demonstration/texture.png")));
//create a byte buffer big enough to store RGBA values
ByteBuffer buffer = BufferUtils.createByteBuffer(4 * decoder.getWidth() * decoder.getHeight());
//decode
decoder.decode(buffer, decoder.getWidth() * 4, PNGDecoder.Format.RGBA);
//flip the buffer so its ready to read
buffer.flip();
//create a texture
int id = glGenTextures();
//bind the texture
glBindTexture(GL_TEXTURE_2D, id);
//tell opengl how to unpack bytes
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
//set the texture parameters, can be GL_LINEAR or GL_NEAREST
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//upload texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, decoder.getWidth(), decoder.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
// Generate Mip Map
glGenerateMipmap(GL_TEXTURE_2D);
return new Texture(id);
}
private int id;
public Texture(int id){
this.id = id;
}
public int getId(){
return id;
}
}
Note that the path of the texture image is not the problem, as the code works without any Exceptions or Compiler errors.请注意,纹理图像的路径不是问题,因为代码工作时没有任何异常或编译器错误。 The PNGDecoder i used can be found here .我使用的 PNGDecoder 可以在这里找到。
The stride and offset argument must be set in bytes when specifying the array of generic vertex attribute data by glVertexAttribPointer
.当通过glVertexAttribPointer
指定通用顶点属性数据数组时,必须以字节为单位设置步幅和偏移量参数。
Furthermore, the uv
coordinates are the 7th and 8th element in the attribute tuple:此外, uv
坐标是属性元组中的第 7 个和第 8 个元素:
glVertexAttribPointer(0, 3, GL_FLOAT, false, 8, 0);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 8*4, 0);
glVertexAttribPointer(1, 3, GL_FLOAT, false, 8, 2);
glVertexAttribPointer(1, 3, GL_FLOAT, false, 8*4, 3*4);
glVertexAttribPointer(2, 2, GL_FLOAT, false, 8, 5);
glVertexAttribPointer(2, 2, GL_FLOAT, false, 8*4, 6*4);
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