learnOpenGL-模版测试

企业开发 2023-09-30 04:04:09 阅读次数: 0

模版缓冲大致流程：
1.启用模板缓冲的写入
2.渲染物体，更新模板缓冲的内容。
3.禁用模板缓冲的写
4.渲染（其它）物体，根据模板缓冲的内容丢弃特定的片段
关键函数：

glEnable(GL_STENCIL_TEST);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
glStencilMask(0xFF); // 每一位写入模板缓冲时都保持原样
glStencilMask(0x00); // 每一位在写入模板缓冲时都会变成0（禁用写入）
glStencilFunc(GLenum func, GLint ref, GLuint mask)
glStencilOp(GLenum sfail, GLenum dpfail, GLenum dppass)

例子：只要一个片段的模板值等于(GL_EQUAL)参考值1，片段将会通过测试并被绘制，否则会被丢弃。

物体轮廓：
1.启用模版缓冲写入，被渲染物体片段更新模版缓冲为1
2.渲染物体
3.禁用模版缓冲写入及深度测试
4.使用另一个绘制边框的片段着色器
5.渲染同一个稍微放大的物体，只有模版缓冲不为1时才绘制片段
6。绘制完一个带边框的物体，重新启用模版缓冲写入和深度测试

glStencilFunc(GL_EQUAL, 1, 0xFF)

main.cpp

#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "shader.h"
#include "stb_image.h"
#include <glm.hpp>
#include <gtc/matrix_transform.hpp>
#include <gtc/type_ptr.hpp>
#include "Camera.h"
#include "Model.h"

Camera* myCamera = new Camera(glm::vec3(0.0f, 0.0f, 3.0f), glm::vec3(0.0f, 0.0f, -1.0f), glm::vec3(0.0f, 1.0f, 0.0f));

void mouse_callback(GLFWwindow* window, double xpos, double ypos) {
    
    
	myCamera->mouseCb(xpos, ypos);
};

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    
    
	myCamera->scrollCb(xoffset, yoffset);
}

GLfloat deltaTime = 0.0f;
GLfloat lastFrame = 0.0f;

void processInput(GLFWwindow* window) {
    
    
	GLfloat currentFrame = glfwGetTime();
	deltaTime = currentFrame - lastFrame;
	lastFrame = currentFrame;
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);
	if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS) {
    
    
		myCamera->pressKeyW(deltaTime);
	}
	if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS) {
    
    
		myCamera->pressKeyS(deltaTime);
	}
	if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS) {
    
    
		myCamera->pressKeyA(deltaTime);
	}
	if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS) {
    
    
		myCamera->pressKeyD(deltaTime);
	}
}


float cubeVertices[] = {
    
    
	// positions          // texture Coords
	-0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
	 0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	-0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 0.0f,

	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	 0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
	-0.5f,  0.5f,  0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,

	-0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	-0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	-0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f, -0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
	-0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
	-0.5f, -0.5f, -0.5f,  0.0f, 1.0f,

	-0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
	 0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	 0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
	-0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
	-0.5f,  0.5f, -0.5f,  0.0f, 1.0f
};
float planeVertices[] = {
    
    
	// positions          // texture Coords (note we set these higher than 1 (together with GL_REPEAT as texture wrapping mode). this will cause the floor texture to repeat)
	 5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
	-5.0f, -0.5f,  5.0f,  0.0f, 0.0f,
	-5.0f, -0.5f, -5.0f,  0.0f, 2.0f,

	 5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
	-5.0f, -0.5f, -5.0f,  0.0f, 2.0f,
	 5.0f, -0.5f, -5.0f,  2.0f, 2.0f
};

int main()
{
    
    
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);

	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	GLFWwindow* window = glfwCreateWindow(800, 600, "test", nullptr, nullptr);
	if (window == nullptr)
	{
    
    
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);

	//glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);

	glewExperimental = GL_TRUE;
	if (glewInit() != GLEW_OK)
	{
    
    
		std::cout << "Failed to initialize GLEW" << std::endl;
		glfwTerminate();
		return -1;
	}

	glViewport(0, 0, 800, 600);

	GLuint cubeVAO, cubeVBO;
	glGenVertexArrays(1, &cubeVAO);
	glBindVertexArray(cubeVAO);
	glGenBuffers(1, &cubeVBO);
	glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, GL_STATIC_DRAW);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
	glBindVertexArray(0);

	unsigned int planeVAO, planeVBO;
	glGenVertexArrays(1, &planeVAO);
	glGenBuffers(1, &planeVBO);
	glBindVertexArray(planeVAO);
	glBindBuffer(GL_ARRAY_BUFFER, planeVBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(planeVertices), &planeVertices, GL_STATIC_DRAW);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
	glBindVertexArray(0);

	GLuint tex;
	glGenTextures(1, &tex);
	int width, height, nrComponents;
	unsigned char* image = stbi_load("container.jpg", &width, &height, &nrComponents, 0);
	if (image) {
    
    
		GLenum format;
		if (nrComponents == 1)
			format = GL_RED;
		else if (nrComponents == 3)
			format = GL_RGB;
		else if (nrComponents == 4)
			format = GL_RGBA;

		glBindTexture(GL_TEXTURE_2D, tex);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, format, GL_UNSIGNED_BYTE, image);
		glGenerateMipmap(GL_TEXTURE_2D);

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

		stbi_image_free(image);
	}

	glm::mat4 model;
	glm::mat4 view;
	glm::mat4 projection;

	Shader* frameShader = new Shader("test.vert", "frame.frag");

	Shader* testShader = new Shader("test.vert", "test.frag");

	Shader* lightShader = new Shader("test.vert", "light.frag");

	//Model* testModel = new Model("ganyu/tex/甘雨.fbx");

	while (!glfwWindowShouldClose(window))
	{
    
    
		processInput(window);
		glfwPollEvents();


		glEnable(GL_DEPTH_TEST);
		//深度测试函数
		glDepthFunc(GL_LESS);

		glEnable(GL_STENCIL_TEST); //启用模板缓冲

		glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
		//参数：1.模板测试失败时的行为，2.模板测试通过，但深度测试失败时的行为，3.模板测试和深度测试都通过的行为
		/*
		GL_KEEP	保持当前储存的模板值
		GL_ZERO	将模板值设置为0
		GL_REPLACE	将模板值设置为glStencilFunc函数设置的ref值
		GL_INCR	如果模板值小于最大值则将模板值加1
		GL_INCR_WRAP	与GL_INCR一样，但如果模板值超过了最大值则归零
		GL_DECR	如果模板值大于最小值则将模板值减1
		GL_DECR_WRAP	与GL_DECR一样，但如果模板值小于0则将其设置为最大值
		GL_INVERT	按位翻转当前的模板缓冲值
		*/

		glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

		testShader->Use();

		glStencilMask(0x00); //绘制底板时不更新缓冲

		glBindVertexArray(planeVAO);
		glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "model"), 1, GL_FALSE, glm::value_ptr(glm::mat4(1.0f)));
		glDrawArrays(GL_TRIANGLES, 0, 6);
		glBindVertexArray(0);

		glStencilMask(0xFF); // 设置一个位编码，与将要写入缓冲的模板值进行与(AND)运算。默认情况下设置的位掩码所有位都为1，不影响输出
		//glStencilMask(0x00); 每一位在写入模板缓冲时都会变成0（禁用写入）  与深度测试中的glDepthMask(GL_FALSE)是等价的

		glStencilFunc(GL_ALWAYS, 1, 0xFF);
		//参数1：模板测试函数。该函数将应用到已储存的模板值和第二个参数上。：GL_NEVER、GL_LESS、GL_LEQUAL、GL_GREATER、GL_GEQUAL、GL_EQUAL、GL_NOTEQUAL和GL_ALWAYS。与深度缓冲类似
		//2：模板测试的参考值，模板缓存的内容会与该值比较，3.掩码，在参考值与模板值测试比较前与他们进行AND运算。

		glUniform1i(glGetUniformLocation(testShader->getProgram(), "texture1"), 0);

		glBindVertexArray(cubeVAO);
		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, tex);

		view = myCamera->getViewMat4();
		glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "view"), 1, GL_FALSE, glm::value_ptr(view));

		projection = glm::perspective(glm::radians(myCamera->getFov()), 800.0f / 600.0f, 0.1f, 100.0f);
		glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "projection"), 1, GL_FALSE, glm::value_ptr(projection));

		model = glm::mat4(1.0f);
		model = glm::translate(model, glm::vec3(-1.0f, 0.0f, -1.0f));
		glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "model"), 1, GL_FALSE, glm::value_ptr(model));
		glDrawArrays(GL_TRIANGLES, 0, 36);
		model = glm::mat4(1.0f);
		model = glm::translate(model, glm::vec3(2.0f, 0.0f, 0.0f));
		glUniformMatrix4fv(glGetUniformLocation(testShader->getProgram(), "model"), 1, GL_FALSE, glm::value_ptr(model));
		glDrawArrays(GL_TRIANGLES, 0, 36);

		glStencilFunc(GL_NOTEQUAL, 1, 0xFF);
		glStencilMask(0x00); // 禁止模板缓冲的写入
		glDisable(GL_DEPTH_TEST);

		frameShader->Use();

		float scale = 1.1f;

		glBindVertexArray(cubeVAO);
		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, tex);

		view = myCamera->getViewMat4();
		glUniformMatrix4fv(glGetUniformLocation(frameShader->getProgram(), "view"), 1, GL_FALSE, glm::value_ptr(view));

		projection = glm::perspective(glm::radians(myCamera->getFov()), 800.0f / 600.0f, 0.1f, 100.0f);
		glUniformMatrix4fv(glGetUniformLocation(frameShader->getProgram(), "projection"), 1, GL_FALSE, glm::value_ptr(projection));

		model = glm::mat4(1.0f);
		model = glm::translate(model, glm::vec3(-1.0f, 0.0f, -1.0f));
		model = glm::scale(model, glm::vec3(scale, scale, scale));
		glUniformMatrix4fv(glGetUniformLocation(frameShader->getProgram(), "model"), 1, GL_FALSE, glm::value_ptr(model));
		glDrawArrays(GL_TRIANGLES, 0, 36);
		model = glm::mat4(1.0f);
		model = glm::translate(model, glm::vec3(2.0f, 0.0f, 0.0f));
		model = glm::scale(model, glm::vec3(scale, scale, scale));
		glUniformMatrix4fv(glGetUniformLocation(frameShader->getProgram(), "model"), 1, GL_FALSE, glm::value_ptr(model));
		glDrawArrays(GL_TRIANGLES, 0, 36);

		glStencilMask(0xFF);
		glStencilFunc(GL_ALWAYS, 0, 0xFF);
		glEnable(GL_DEPTH_TEST);

		glfwSwapBuffers(window);
	}


	glfwTerminate();
	return 0;
}

片段着色器

#version 330 core
out vec4 FragColor;

in vec2 TexCoords;

void main()
{
    
    
    FragColor = vec4(0.04, 0.28, 0.26, 1.0);
}

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