Sprite.cpp

#include "Sprite.h"
#include "Vertex.h"
#include <cstddef>
#include "ResourceManager.h"
namespace NeroEngine{
	Sprite::Sprite() :_vboID(0){
	}


	Sprite::~Sprite()
	{
		if (_vboID != 0){
			glDeleteBuffers(1, &_vboID);
		}
	}

	void Sprite::init(float x, float y, float width, float height, std::string texturePath){
		_x = x;
		_y = y;
		_width = width;
		_height = height;

		_texture = ResourceManager::getTexture(texturePath);


		if (_vboID == 0){
			glGenBuffers(1, &_vboID); // create a buffer
		}

		Vertex vertexData[6];
		//first triangle
		//right bottom
		vertexData[0].setPosition(x + width, y + height);
		vertexData[0].setUV(1.0f, 1.0f);
		//left bottom
		vertexData[1].setPosition(x, y + height);
		vertexData[1].setUV(0.0f, 1.0f);
		//left top
		vertexData[2].setPosition(x, y);
		vertexData[2].setUV(0.0f, 0.0f);

		//second triangle
		//left top
		vertexData[3].setPosition(x, y);
		vertexData[3].setUV(0.0f, 0.0f);
		//right top
		vertexData[4].setPosition(x + width, y);
		vertexData[4].setUV(1.0f, 0.0f);
		//right bottom
		vertexData[5].setPosition(x + width, y + height);
		vertexData[5].setUV(1.0f, 1.0f);

		for (int i = 0; i < 6; i++){
			vertexData[4].setColor(255, 0, 255, 255);
		}
		vertexData[4].setColor(0, 0, 255, 255);
		vertexData[4].setColor(0, 255, 0, 255);


		glBindBuffer(GL_ARRAY_BUFFER, _vboID);//先将buffer绑定到当前
		glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW);//将顶点数组放入这个buffer

		glBindBuffer(GL_ARRAY_BUFFER, 0);
	}
	void Sprite::draw(){

		glBindTexture(GL_TEXTURE_2D, _texture.id);

		glBindBuffer(GL_ARRAY_BUFFER, _vboID);
		glEnableVertexAttribArray(0);

		glEnableVertexAttribArray(1);

		glEnableVertexAttribArray(2);

		//position attrib pointer
		glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, position));
		//color attrib pointer
		glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(Vertex), (void *)offsetof(Vertex, color));

		//uv attrib pointer
		glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void *)offsetof(Vertex, uv));

		glDrawArrays(GL_TRIANGLES, 0, 6);

		glDisableVertexAttribArray(0);

		glDisableVertexAttribArray(1);

		glDisableVertexAttribArray(2);


		glBindBuffer(GL_ARRAY_BUFFER, 0);
	}
}