Question

我正在尝试将2D映射到三角形的纹理。但是目前，我只能得到一个渐变色的三角形，上面没有任何纹理。这意味着，我在glsl中的纹理函数总是返回vec4（1,1,1,1）并且我的textCoords正在工作。我该如何解决？尝试任何建议都会有所帮助！

顺便说一下，已经为此工作了3天。

纹理类中的

：

构造

Texture::Texture(const std::string& fileName){

   int width, height, numComponents;
   //float* imageData = stbi_loadf(fileName.c_str(), &width, &height, &numComponents, 4);
   unsigned char* imageData = stbi_load(fileName.c_str(), &width, &height, &numComponents, 4);
   if(imageData == NULL){
      cerr << "Texture loading failed for "<<fileName<< endl;
   }

   glGenTextures(1, &m_texture);
   glBindTexture(GL_TEXTURE_2D, m_texture);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

   glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA8,width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);


   stbi_image_free(imageData);
 }

纹理绑定功能：

void Texture::Bind(){
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D, m_texture);
}

在我的main.cpp中：

m_shader.generateProgramObject();
m_shader.attachVertexShader( getAssetFilePath("VertexShader.vs").c_str() );
m_shader.attachFragmentShader( getAssetFilePath("FragmentShader.fs").c_str()   );
m_shader.link();

// texture created here
texture = Texture("Assets/bricks.jpg");


// enable vertex attribute indices
glGenVertexArrays(1, &m_vao_triangle);
glBindVertexArray(m_vao_triangle);

// Enable the attribute index location for "position" when rendering.
GLint positionAttribLocation = m_shader.getAttribLocation( "position" );
glEnableVertexAttribArray(positionAttribLocation);

GLint textCoordLocation = m_shader.getAttribLocation( "atextCoord" );
glEnableVertexAttribArray(textCoordLocation);


// Restore defaults
glBindVertexArray(0);


CHECK_GL_ERRORS;

将三角形数据上传到缓冲区

vec3 triangleVertices[] = {
    // Construct equalaterial triangle
    vec3(0.0f, 0.0f, 0.0f),
    vec3(0.25f, 1.0f, 0.0),
    vec3(0.5f, 0.0f, 0.0f)
};

vec2 textCoords[] = {
         vec2(1.0f, 0.0f), 
         vec2(0.25f, 1.0f), 
         vec2(0.5f, 0.0f)};



// Generate a vertex buffer object to hold the triangle's vertex data.
glGenBuffers(1, &m_vbo_triangle);

//-- Upload triangle vertex data to the vertex buffer:
glBindBuffer(GL_ARRAY_BUFFER, m_vbo_triangle);
glBufferData(GL_ARRAY_BUFFER, sizeof(triangleVertices), triangleVertices,
        GL_STATIC_DRAW);

glBindBuffer(GL_ARRAY_BUFFER, 0);
CHECK_GL_ERRORS;




//====generate buffer for holding texture coordinates====
glGenBuffers(1, &m_uv_triangle);
glBindBuffer(GL_ARRAY_BUFFER, m_uv_triangle);
glBufferData(GL_ARRAY_BUFFER, sizeof(textCoords), textCoords,
             GL_STATIC_DRAW);

// Unbind the target GL_ARRAY_BUFFER, now that we are finished using it.
glBindBuffer(GL_ARRAY_BUFFER, 0);

CHECK_GL_ERRORS;

将缓冲区数据映射到着色器

 glBindVertexArray(m_vao_triangle);

 glBindBuffer(GL_ARRAY_BUFFER, m_vbo_triangle);
 GLint positionAttribLocation = m_shader.getAttribLocation( "position" );
 glVertexAttribPointer(positionAttribLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);



 glBindBuffer(GL_ARRAY_BUFFER, m_uv_triangle);
 GLint textCoordLocation = m_shader.getAttribLocation( "atextCoord" );
 glVertexAttribPointer(textCoordLocation,2, GL_FLOAT, GL_FALSE, 0, nullptr);


 //-- Unbind target, and restore default values:
 glBindBuffer(GL_ARRAY_BUFFER, 0);
 glBindVertexArray(0);

 CHECK_GL_ERRORS;

将制服上传到着色器

    m_shader.enable();

    ...

    GLint uniformLocation_diffuse = m_shader.getUniformLocation("diffuse");
    glUniform1i(uniformLocation_diffuse, 0);
    CHECK_GL_ERRORS;

    m_shader.disable();

    CHECK_GL_ERRORS;

在我的绘画功能中：

glBindVertexArray(m_vao_triangle);
//   below I tried, but didn't work
//   glClear(GL_STENCIL_BUFFER_BIT);
//   glEnable(GL_BLEND);
//   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
//   glEnable(GL_DEPTH_TEST);

texture.Bind();
//   do these below: 
//   glActiveTexture(GL_TEXTURE0);
//   glBindTexture(GL_TEXTURE_2D, texture.m_texture);

m_shader.enable();

glDrawArrays(GL_TRIANGLES, 0, 3);


m_shader.disable();


// Restore defaults
glBindVertexArray(0);

CHECK_GL_ERRORS;

在这里，我还将附上我的着色器顶点着色器：

#version 330

in vec3 position;
in vec2 atextCoord;

uniform mat4 transform;
out vec2 textCoord;

void main() {
   gl_Position = transform * vec4(position, 1.0);
   textCoord = atextCoord;
}

我的片段着色器：

#version 330

uniform sampler2D diffuse;

out vec4 fragColor;
in vec2 textCoord;

void main() {

   fragColor = vec4(texture(diffuse, textCoord).rgb,1.0) *    vec4(textCoord,0.0,1.0); 
   // texture(...) shows vec4(1,1,1,1)
   // radiant colour can only prove my textCoord is working
   // fragColor = texture(diffuse, textCoord);   <- only shows a default texture
}

here is the running result

Here is the texture image

Answer 1

我找到了一种方法让它发挥作用。

我复制Texture构造函数中的每一行并将其粘贴到draw（），而不是调用texture.Bind（）。看起来我在它准备绘制几何图形之前制作纹理，这种方式正在发挥作用。

但我仍然必须知道为什么会这样。对于编码风格，我仍然需要将我的代码放在Texture类中。您是否介意提供以前发生的事情的解决方案？

it looks like this right now

OpenGL GLSL纹理函数总是返回vec4（1,1,1,1），白色三角形

1 个答案: