gtk+opengl 之变色的三角形

#include <glib.h>
#include <gtk/gtk.h>
#include "GL/glew.h"
#include <stdio.h>
#include <math.h>
 
static GtkWidget *window;
 
FILE *fp;
 
// Shaders 以定义字符串的方式给出
const GLchar* vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 position;\n"
"void main()\n"
"{\n"
"gl_Position = vec4(position.x, position.y, position.z, 1.0);\n"
"}\0";

const GLchar* fragmentShaderSource = "#version 330 core\n"
"uniform vec4 mycolor;\n"
"void main()\n"
"{\n"
"gl_FragColor = mycolor;\n"
"}\n\0";
 
 
//main函数调用，定义成全局形式
GLuint VAO, VBO;/*声明VAO,VBO*/
GLuint vertexShader, fragmentShader, shaderProgram;/*声明着色器对象和着色器程序对象*/
 
void slog_init()
{
	fp = fopen("log.txt", "a+");
	if(NULL == fp){
		printf("log_init failed.");
	}
}
 
void slog(char * fmt,...)
{
	va_list  ap;
 
	if( NULL != fp){
		va_start(ap, fmt);
		vfprintf(fp, fmt, ap);
		va_end(ap);
		fprintf(fp, "\n");
		fflush(fp);
	}
}
 
//VBO,VAO初始化
void draw_init()
{
	GLfloat vertices[] = {
		-0.5f,-0.5f,0.0f,
		0.5f,-0.5f,0.0f,
		0.0f,0.5f,0.0f	};
 
	//生成顶点数组对象VAO
	glGenVertexArrays(1, &VAO);
	//生成顶点缓冲对象VBO
	glGenBuffers(1, &VBO);
	//绑定VAO
	glBindVertexArray(VAO);
	//绑定VBO
	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	//复制顶点数据到VB0
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
	//解释顶点数据链接方式
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_TRUE, 3 * sizeof(GLfloat),(GLvoid *) 0);
	//glVertexAttribPointer(0, 3, GL_FLOAT, GL_TRUE, 0, 0);/*两个顶点属性之间无间隙，第五个参数可设置为0*/
	glEnableVertexAttribArray(0);/*开启顶点属性，参数是顶点属性location*/
 
	//解绑VBO
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	//解绑VAO
	glBindVertexArray(0);

	//生成顶点着色器
	vertexShader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);/*着色器源码附加到着色器对象上*/
	glCompileShader(vertexShader);/*编译顶点着色器*/
 
	//检查顶点着色器是否编译成功，不成功输出错误信息
	GLint success;
	GLchar infoLog[512];
	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		slog("---shaderinit-----GetShaderiv error=[%d]", success);
		glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
		glDeleteShader(vertexShader);
	}
	
	//生成片段着色器
	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
	glCompileShader(fragmentShader);
	
	//检查片段着色器是否编译成功，不成功输出错误信息
	glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		slog("---shaderinit-----GetShaderiv error=[%d]", success);
		glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
		glDeleteShader(fragmentShader);
	}
 
	//生成着色器程序对象，并连接着色器
	shaderProgram = glCreateProgram();
	glAttachShader(shaderProgram, vertexShader);/*把编译好的着色器附加到着色器程序对象上*/
	glAttachShader(shaderProgram, fragmentShader);
 
	//尝试链接
	glLinkProgram(shaderProgram);
	//检查链接着色器程序是否成功，不成功输出错误信息
	glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
	if(!success)
	{
		slog("---shaderinit-----GetShaderiv error=[%d]", success);
		glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
		glDeleteProgram(shaderProgram);
	}
 
	//删除着色器
	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);
}
 
gboolean
display(gpointer user_data)
{
    //    给area发送一个render信号，要开始画三角形了
	gtk_gl_area_queue_render(GTK_GL_AREA(user_data));
 
    //   不停下来，一直画吧
   return TRUE;
}

gboolean
render(GtkWidget *area, gpointer user_data)
{
	glClearColor(0.2f, 0.3f, 0.3f, 1.0f);// clear the window
	glClear(GL_COLOR_BUFFER_BIT);
	
    //    将颜色传入fragmentshader，蓝色分量一直变化
	int timeValue = time(NULL);
	float blueValue = sin(timeValue) / 2.0f + 0.5f;
	glUniform4f(glGetUniformLocation(shaderProgram, "mycolor"), 0.0f, 0.0f, blueValue, 1.0f);

    //绘制过程	
	glUseProgram(shaderProgram);
	glBindVertexArray(VAO);
	glDrawArrays(GL_TRIANGLES, 0, 3);
	glBindVertexArray(0);

  return TRUE;
}
 
void
realize(GtkWidget *area, gpointer user_data)
{
	gtk_gl_area_make_current(GTK_GL_AREA(area));
	if (gtk_gl_area_get_error(GTK_GL_AREA(area)) != NULL)
        	return;
 
	glewExperimental = GL_TRUE;
	gboolean ret = glewInit();
	if(ret != GLEW_OK)
	{
		slog("<%s>--------glew init error [%s]", __func__, glewGetErrorString(ret));
	}
	
	draw_init();
	
    //    添加定时时间，每100ms调用一次display
	g_timeout_add(100, display, area);
}
 
static void create_window(void)
{
	window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
 
	gtk_window_set_title(GTK_WINDOW(window),"Triangle");
	gtk_window_set_position(GTK_WINDOW(window),GTK_WIN_POS_CENTER); 
	
	gtk_window_set_resizable(GTK_WINDOW(window), TRUE);
	gtk_widget_set_size_request(window, 800,800); 
 
	GError *error = NULL;
 
	GtkWidget *area = gtk_gl_area_new();
	gtk_gl_area_set_required_version(GTK_GL_AREA(area), 3, 2);
	gtk_gl_area_set_auto_render(GTK_GL_AREA(area), FALSE);
	
	g_object_connect(area,
			"signal::render", render, NULL,
			"signal::realize", realize, NULL,
			NULL);
 
	gtk_container_add(GTK_CONTAINER(window), GTK_WIDGET(area));
 
	gtk_widget_show_all(window);
}
 
int main(int argc, char *argv[])
{
	slog_init();
	gtk_init(&argc, &argv);
 
	create_window();
 
	gtk_main();
}

编译

gcc -o triangle triangle.c `pkg-config --cflags --libs gtk+-3.0` -lSOIL -lGLEW -lGL -lm
执行效果（不知道怎么放视频）

反正就是颜色来回变化