shader/scene.cpp

#include "scene.h"
#include "ggl.h"
#include "utils.h"
#include "ground.h"

GLuint vbo, ebo;
GLuint program;
GLint positionLocation, modelMatrixLocation, viewMatrixLocation, projectionMatrixLocation, colorLocation;//顶点、模型矩阵、视图矩阵、投影矩阵的位置
GLint texcoordLocation, textureLocation;//顶点坐标插槽位置、贴图插槽位置
GLuint texture;
glm::mat4 modelMatrix, viewMatrix, projectionMatrix;
Ground ground;

void Init() {
	/*1.初始化vbo并为vbo赋值*/
	float data[] = {
		-0.2f,-0.2f,0.0f,1.0f,  1.0f,0.0f,0.0f,1.0f, 0.0f,0.0f,
		0.2f,-0.2f,0.0f,1.0f,  0.0f,1.0f,0.0f,1.0f, 1.0f,0.0f,
		0.0f,0.2f,0.0f,1.0f,  0.0f,0.0f,1.0f,1.0f, 0.5f,1.0f
	};
	glGenBuffers(1, &vbo);//创建vbo
	glBindBuffer(GL_ARRAY_BUFFER, vbo);//绑定下面要操作的vbo
	glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 30, data, GL_STATIC_DRAW);//发送cpu数据到GPU
	glBindBuffer(GL_ARRAY_BUFFER, 0);//关闭绑定

	/*1.2使用vbo定义绘画顺序*/
	unsigned short indexes[] = { 0,1,2 };
	glGenBuffers(1, &ebo);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned short) * 3, indexes, GL_STATIC_DRAW);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

	/*2.编译shader*/
	int fileSize = 0;
	unsigned char * shaderCode = LoadFileContent("Res/test.vs", fileSize); 
	GLuint vsShader = CompileShader(GL_VERTEX_SHADER, (char*)shaderCode);//编译 vertex shader
	delete shaderCode;

	shaderCode = LoadFileContent("Res/test.fs", fileSize);
	GLuint fsShader = CompileShader(GL_FRAGMENT_SHADER, (char*)shaderCode);//编译 fragment shader
	delete shaderCode;

	/*3.链接 vertex shader 和 fragment shader*/
	program = CreateProgram(vsShader, fsShader);
	glDeleteShader(vsShader);
	glDeleteShader(fsShader);

	/*4.获取顶点、模型矩阵、视图矩阵、投影矩阵，在GPU中的位置，有这个位置后面才能对其进行赋值操作*/
	/*
	attribute vec4 position;
	uniform mat4 ModelMatrix;
	uniform mat4 ViewMatrix;
	uniform mat4 ProjectionMatrix;
	*/
	positionLocation = glGetAttribLocation(program, "position");
	colorLocation = glGetAttribLocation(program, "color");
	texcoordLocation = glGetAttribLocation(program, "texcoord");

	modelMatrixLocation = glGetUniformLocation(program, "ModelMatrix");
	viewMatrixLocation = glGetUniformLocation(program, "ViewMatrix");
	projectionMatrixLocation = glGetUniformLocation(program, "ProjectionMatrix");
	textureLocation = glGetUniformLocation(program, "U_Texture");
	modelMatrix = glm::translate(0.0f, 0.0f, -0.6f);

	texture = CreateTexture2DFromBMP("Res/test.bmp");

	ground.Init();
}
void SetViewPortSize(float width, float height) {
	//5.1.设置投影矩阵
	projectionMatrix = glm::perspective(60.0f, width / height, 0.1f, 1000.0f);
}
void Draw() {
	float frameTime = GetFrameTime();
	glClearColor(0.1f, 0.4f, 0.6f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	ground.Draw(viewMatrix, projectionMatrix);

	glUseProgram(program);

	/*5.2.把MVP矩阵赋值到显卡中*/
	glUniformMatrix4fv(modelMatrixLocation, 1, GL_FALSE, glm::value_ptr(modelMatrix));//设置模型矩阵
	glUniformMatrix4fv(viewMatrixLocation, 1, GL_FALSE, glm::value_ptr(viewMatrix));
	glUniformMatrix4fv(projectionMatrixLocation, 1, GL_FALSE, glm::value_ptr(projectionMatrix));
	

	/*6.设置绘制的数据*/
	glBindTexture(GL_TEXTURE_2D, texture);
	glUniform1i(textureLocation, 0);//设置贴图
	glBindBuffer(GL_ARRAY_BUFFER, vbo);//绑定vbo，就是1部分设置的几个顶点数据
	glEnableVertexAttribArray(positionLocation);//启用顶点插槽
	glVertexAttribPointer(positionLocation, 4, GL_FLOAT, GL_FALSE, sizeof(float) * 10, 0);//把vbo顶点数据填入顶点插槽
	glEnableVertexAttribArray(colorLocation);//启用颜色插槽
	glVertexAttribPointer(colorLocation, 4, GL_FLOAT, GL_FALSE, sizeof(float) * 10, (void*)(sizeof(float) * 4));//把vbo颜色数据填入颜色插槽
	glEnableVertexAttribArray(texcoordLocation);
	glVertexAttribPointer(texcoordLocation, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 10, (void*)(sizeof(float) * 8));

	glBindBuffer(GL_ARRAY_BUFFER, 0);

	/*7.绘制*/
	//glDrawArrays(GL_TRIANGLES, 0, 3);//顺序绘制
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
	glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, 0);//按照ebo顺序绘制
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	
	
	/*8.解除绑定*/
	glUseProgram(0);
}