Debug No5 basic lighting

2022 Year afternoon 15：14

1.bug state ： Do not show rendering . An error message indicates that vertex shaders and fragment shaders failed to compile .

analysis ：Asset No problem with the data , There may be problems in the component production line , The first step is initModel(), And then there was initShader(). Moreover is rend（） The order problem in , Check step by step .

solve ： Find a place initShader（） It's through cube Shader call . It is found that , Because the name of the packaged component , Conflict with member function of class with the same name , Instead of calling here to compile two cubes shader Component method , Instead, only one compiled cube is called shader Member method of .

Harvest ： Avoid conflicting naming when packaging . Member methods are called through class objects , Ordinary functions can be called directly . It can be seen that the foundation is not solid .

---

 2.bug state ： Show only one （ Render complete ）cube Cube , Instead of displaying the light cube .

  analysis ： Although the vertex attributes passed in have position and UV. But I think for the light cube, we can omit the texture and UV Information . So the problem here must be , I set to read too much attribute information , And in the rend() The link does not resolve the corresponding variable in the shader . Or attribute information is missing in the shader I read , But resolved some variables that do not exist in the shader . But either way , I didn't even see VS The compiler reported an error , Unless the error about the shader is the error of opening the shader file or the shader and its obvious syntax error .

  solve ： Deleted redundant variables such as textures in shaders , stay rend() The link has no bound texture .

Harvest ： In fact, shader reading data is very flexible , For example, the native data of vertex attributes has texture , Location , Color data , But I You can only receive data that I may use in vertex shaders . For example, the vertex shader of the light cube only receives position information and I don't need to deal with other attribute information when rendering .

void rend()
{
    // buffer 
	glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
	glEnable(GL_DEPTH_TEST);
	// Describe the camera 
	_projMatrix = glm::perspective(glm::radians(45.0f), 1.0f, 0.1f, 100.0f); // Custom projection matrix 
	_camera.update();   // Update the camera matrix in real time 

	cube_shader.shader_Begin();
	    // Resource description 
		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, _texture);
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, _texture2);
		glm::mat4 _modelMatrix(1.0f);
		// Resolve shaders   Variable , And pass in the data 
		cube_shader.setMatrix("_modelMatrix", _modelMatrix);
		cube_shader.setMatrix("_viewMatrix", _camera.getMatrix());// Input data to the matrix of the corresponding name 
		cube_shader.setMatrix("_projMatrix", _projMatrix);

		cube_shader.setInt("_texture", 0);
		cube_shader.setInt("_texture2", 1);
		// Bind vertex array , Draw the outline 
		glBindVertexArray(VAO_cube);
		glDrawArrays(GL_TRIANGLES, 0, 36);

	cube_shader.shader_End();

	sun_shader.shader_Begin();
		// Resolve shaders   Variable , And pass in the data 
		sun_shader.setMatrix("_modelMatrix", _modelMatrix);
		sun_shader.setMatrix("_viewMatrix", _camera.getMatrix());// Input data to the matrix of the corresponding name 
		sun_shader.setMatrix("_projMatrix", _projMatrix);

		_modelMatrix = glm::translate(_modelMatrix, glm::vec3(3.0f, 0.0f, 0.0f));
		sun_shader.setMatrix("_modelMatrix", _modelMatrix);
        // Bind vertex array , Draw the outline 
		glBindVertexArray(VAO_sun);
		glDrawArrays(GL_TRIANGLES, 0, 36);
	sun_shader.shader_End();
	
}

summary ： After grasping the basic framework and detailed framework of knowledge , After summarizing the overall framework , We should practice more . Improve proficiency .

---

3.bug3 : Rendering effect , The light is blue .（ Light intensity setting from 0.5--1.0---1.5） But the contrast between the color and the original picture shows that it is incorrect .

  analysis ： I guess it's because the color of the light source is read incorrectly , But after checking the process for many times, no data error was found . stay RenderDoc in , Prompt vertex shader compilation problem ... After the output light source , I found that the light source was blue , But after observation, we found that this blue is not a coincidence , It is （1.0f) Blue +（1.0f) Green and blue . And I adjust the red value in Figure 2 , It doesn't work anyway , But blue and green values are available . So connect the two , See light suddenly ！ It turned out that the red value passed during initialization topped the red value at the time of assignment , Invalidate the red color in the assignment .

// happen bug Front code 
  
glm::vec3 ligntColor(1.0f);

// This way of writing means only changing 1.0f Red , Other colors are not transmitted .
// This is related to glm::mat3(1.0f) There are differences in the way of writing , The latter means to pass in an identity matrix .

Figure 1

Figure 2

Figure 3

  resolvent ： When declaring the color and position of the light source , Do not write initialization as glm::vec3 light_color(1.0f); Instead, re assign values below . Or initialize directly to the target value .

But it has not been solved RenderDoc Wrong report in . The tip is API The use is not standardized . The reason has not been proved .

Final effect

Harvest ： Testing is the only criterion for practicing truth , Don't let go of any details . In addition to glm::vec3 The data is C++ data , and uniform It's from CPU Direct transmission GPU The data of , So you need to resolve variables in shaders alone . but uniform Variable data and uniform irrelevant , It will only affect the transmission mode .

---

4.bug state ： Under diffuse reflection cube Lose texture .

  analysis ： It indicates that there is an error in the texture , There is a problem in reading data of shader in the first step , So I checked the vertex attribute pointer , It is found that the offset is taken incorrectly , The color is normal after modification .

---

The final summary ：  I need to improve my ability , Is the ability to generalize errors into technical terms . such as ： Not as expected bug There are many states , But there is only one precise generalization . Code capabilities and debug The improvement of ability , It's a process of constantly simplifying requirements . A few days ago bug It is easy to change the process type , But now bug You need to analyze data through data .