struct Texture {
	unsigned int textureId;
	Texture(int height = 0, int width = 0, vec3* image = NULL) {
		glGenTextures(1, &textureId);
		glBindTexture(GL_TEXTURE_2D, textureId);    // binding
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_FLOAT, image); //Texture -> GPU
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	}
};


...

class Test : public Drawable {
public:
	std::vector<vec2> tex;
	Texture texture;
public:
	Test() { Animate(0); }

	void Create() {
		Drawable::Create();

		pts.clear();
		tex.clear();

		pts.push_back(vec2(0, 2));
		pts.push_back(vec2(2, 0));
		pts.push_back(vec2(0, 0));

		tex.push_back(vec2(0, 1));
		tex.push_back(vec2(1, 0));
		tex.push_back(vec2(0, 0));

		int w = 128;
		float s = 1.0f / w;

		vec3* image = new vec3[w * w];
		for (int y = 0; y < w; y++) {
			for (int x = 0; x < w; x++) {
				if (x > 64) {
					image[x * w + y] = vec3(0, 1, 0);
				}
				else {
					image[x * w + y] = vec3(1, 0, 0);
				}
			}
		}

		texture = Texture(w, w, image);


		glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
		glBufferData(GL_ARRAY_BUFFER, sizeof(vec2) * pts.size(), &pts[0], GL_STATIC_DRAW);
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, NULL);

		glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
		glBufferData(GL_ARRAY_BUFFER, sizeof(vec2) * tex.size(), &tex[0], GL_STATIC_DRAW);
		glEnableVertexAttribArray(1);
		glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, NULL);
	}

	void Draw() {
		glUseProgram(shaderTProgram);
		glBindVertexArray(vao);

		mat4 MVPTransform = camera.V() * camera.P();

		int location = glGetUniformLocation(shaderTProgram, "MVP");
		if (location >= 0) glUniformMatrix4fv(location, 1, GL_TRUE, MVPTransform);
		else printf("uniform MVP cannot be set\n");

		int sampler = 0;
		location = glGetUniformLocation(shaderTProgram, "samplerUnit");
		glUniform1i(location, sampler);
		glActiveTexture(GL_TEXTURE0 + sampler);
		glBindTexture(GL_TEXTURE_2D, texture.textureId);

		glDrawArrays(GL_TRIANGLES, 0, pts.size());

		glUseProgram(shaderProgram);
	}

	void Animate(float t) {
		sx = 0.8;
		sy = 0.8;
		UpdateM();
	}

	void UpdateM() {
		Mscale = mat4(sx, 0, 0, 0,
			0, sy, 0, 0,
			0, 0, 1, 0,
			0, 0, 0, 1);

		Mtranslate = mat4(1, 0, 0, 0,
			0, 1, 0, 0,
			0, 0, 1, 0,
			wTx, wTy, 0, 1);

		MrotateY = mat4(cosf(fiY), 0, -sinf(fiY), 0,
			0, 1, 0, 0,
			sinf(fiY), 0, cosf(fiY), 0,
			0, 0, 0, 1);

		MrotateZ = mat4(cosf(fiZ), sinf(fiZ), 0, 0,
			-sinf(fiZ), cosf(fiZ), 0, 0,
			0, 0, 1, 0,
			0, 0, 0, 1);
	}
};