Haxel Engine learning 23 --- Transform_ce "iskeypressed-优快云博客

本文介绍在Hazel游戏引擎中如何使用模型矩阵(Model Matrix)来控制游戏对象的位置、旋转和缩放，通过按键控制对象移动，以及如何在渲染时将模型矩阵传递给着色器，实现多个对象的独立变换。

Cherno 视频：https://www.youtube.com/watch?v=2k5FjtMNQsM&list=PLlrATfBNZ98dC-V-N3m0Go4deliWHPFwT&index=39

代码：https://github.com/DXT00/Hazel_study/tree/a6b65fa3835791f13e1566e84b094d0708a9f2e6/Hazel

For every object -->Transform have to be per Mesh or per Object

For camera transform--> Transform is for the whole scene

即：为每个Object传递Model Matrix(Transform matrix)

首先改变Renderer接口，提交CameraMatrix同时，还要提交Object的TransformMatrix

Object的TransformMatrix会通过Uniform传递到Shader!

	void Renderer::Submit(const std::shared_ptr<VertexArray>& vertexArray, const std::shared_ptr<Shader>& shader,const glm::mat4& transform)
	{
		shader->Bind();
		shader->SetUniformMat4("u_ViewProjection", s_SceneData->ViewProjectionMatrix);
		shader->SetUniformMat4("u_Transform", transform);
		vertexArray->Bind();
		RenderCommand::DrawIndex(vertexArray);

	}

通过四个按键控制Object的Position :J,L,I,K键

if (Hazel::Input::IsKeyPressed(HZ_KEY_J))
{
	m_SquarePosition.x -= m_SquareMoveSpeed * ts;
}
else if (Hazel::Input::IsKeyPressed(HZ_KEY_L))
{
	m_SquarePosition.x += m_SquareMoveSpeed * ts;
}
if (Hazel::Input::IsKeyPressed(HZ_KEY_I))
{
	m_SquarePosition.y += m_SquareMoveSpeed * ts;
}
else if (Hazel::Input::IsKeyPressed(HZ_KEY_K))
{
	m_SquarePosition.y -= m_SquareMoveSpeed * ts;
}

glm::mat4 transform = glm::translate(glm::mat4(1.0f), m_SquarePosition);
Hazel::Renderer::Submit(m_SquareVA, m_SquareShader, transform);

F5:

可以看到，我们按下 J,K,L,I会改变方形的位置，而如果改变相机的Matrix,场景中的所有物体的位置或者旋转会一并改变

还使用glm::scale对方形进行缩放

glm::mat4 scale = glm::scale(glm::mat4(1.0f), glm::vec3(0.1f));


glm::mat4 transform = glm::translate(glm::mat4(1.0f), m_SquarePosition)*scale;
Hazel::Renderer::Submit(m_SquareVA, m_SquareShader, transform);

创造多个Objects:

	void OnUpdate(Hazel::TimeStep ts) override
	{
		HZ_TRACE("Delta time: {0}s ({1}ms)", ts.GetSeconds(), ts.GetMilliseconds());

		//float timestep = ts;//相当一 timestep = float(ts)

		if (Hazel::Input::IsKeyPressed(HZ_KEY_LEFT))
		{
			m_CameraPosition.x -= m_CameraMoveSpeed * ts;
		}
		else if (Hazel::Input::IsKeyPressed(HZ_KEY_RIGHT))
		{
			m_CameraPosition.x += m_CameraMoveSpeed * ts;
		}
		if (Hazel::Input::IsKeyPressed(HZ_KEY_UP))
		{
			m_CameraPosition.y += m_CameraMoveSpeed * ts;
		}
		else if (Hazel::Input::IsKeyPressed(HZ_KEY_DOWN))
		{
			m_CameraPosition.y -= m_CameraMoveSpeed * ts;
		}
		if (Hazel::Input::IsKeyPressed(HZ_KEY_A))
		{
			m_CameraRotation += m_CameraRotateSpeed * ts;
		}
		else if (Hazel::Input::IsKeyPressed(HZ_KEY_D))
		{
			m_CameraRotation -= m_CameraRotateSpeed * ts;
		}
		


		/*if (Hazel::Input::IsKeyPressed(HZ_KEY_J))
		{
			m_SquarePosition.x -= m_SquareMoveSpeed * ts;
		}
		else if (Hazel::Input::IsKeyPressed(HZ_KEY_L))
		{
			m_SquarePosition.x += m_SquareMoveSpeed * ts;
		}
		if (Hazel::Input::IsKeyPressed(HZ_KEY_I))
		{
			m_SquarePosition.y += m_SquareMoveSpeed * ts;
		}
		else if (Hazel::Input::IsKeyPressed(HZ_KEY_K))
		{
			m_SquarePosition.y -= m_SquareMoveSpeed * ts;
		}
*/

		Hazel::RenderCommand::SetClearColor({ 0.1f, 0.1f, 0.1f, 1 });
		Hazel::RenderCommand::Clear();
	/*	m_Camera.SetPosition({ 0.5f,0.5f,0.0f });
		m_Camera.SetRotation(45);*/
		m_Camera.SetPosition(m_CameraPosition);
		m_Camera.SetRotation(m_CameraRotation);
		Hazel::Renderer::BeginScene(m_Camera);

		glm::mat4 scale = glm::scale(glm::mat4(1.0f), glm::vec3(0.1f));
		for (int x = 0; x <5; x++)
		{
			for (int y = 0; y < 5; y++)
			{
				glm::vec3 pos(x*0.11f, y*0.11f, 0.0f);
				glm::mat4 transform = glm::translate(glm::mat4(1.0f), pos)*scale;
				Hazel::Renderer::Submit(m_SquareVA, m_SquareShader, transform);

			}

		}

		//glm::mat4 transform = glm::translate(glm::mat4(1.0f), m_SquarePosition)*scale;
		//Hazel::Renderer::Submit(m_SquareVA, m_SquareShader, transform);
		Hazel::Renderer::Submit(m_VertexArray, m_Shader);
		Hazel::Renderer::EndScene();

	}