OpenGL Rendering Pipeline Code

Requirement

Requirement

• Below are the list of the suggestion you should know about before you proceed.
• Core language feature you wish to used.
• Otherwise you can’t create the program, right?
• Basic rules of resource allocation and management.
• In this slide, we will request the hardware to do the work for us. Remember to release the hardware resource once the program finished.
• CPU and GPU.
• Some knowledge of the hardware helps in this slide.

Requirement

• In this slide, we will use the specification:
• OpenGL version 3.3 or above.
• With the requirement listed below:
• C++ – Main programming languages
• GLFW – OpenGL utility library
• glad – OpenGL loading library

Requirement

• In addition, we will use some optional system to help build our project, you can decide to use it or not:
• CMake – Build system

Before we start

Before we start

• We won’t cover the installation process since each platform has different setup.
• Consider the following additional lecture from online:
• https://learnopengl.com/Getting-started/Creating-a-window

Before we start

• Install CMake
• Suggest to install version 3.3 or above
• Build and install GLFW
• Suggest to install version 3.3 or above
• Set up glad
• Remember to download the patch your computer can perform (version 3.3 in this case).

Window

Window

• General execute step.

Window

Window

Window

Window

Window

Window

Render pipeline code

vertex_array_objects_ebo.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/vertex_array_objects_ebo.png

Render pipeline code

• Below are the components user can modify
• Vertex Shader
• Tessellation
• Geometric Shader
• Fragment Shader

Render pipeline code

• Setup
• Vertex array object.
• Vertex buffer object.
• Element buffer object.

vertex_array_objects_ebo.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/vertex_array_objects_ebo.png

Render pipeline code

• Generate the OpenGL object.

Render pipeline code

• Bind the VAO.
• Bind the buffer object to vertex array object and specify the data (copy them into OpenGL context memory).

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Render pipeline code

• Enable and specify the generic vertex attribute array.

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vertex_attribute_pointer.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/vertex_attribute_pointer_interleaved.png

Render pipeline code

• Setup
• Texture
• Different system from vertex array object.

Texture mapping demonstration animation.gif – Drummyfish – CC0 1.0 Universal (CC0 1.0) Public Domain Dedication

https://commons.wikimedia.org/wiki/File:Texture_mapping_demonstration_animation.gif

Render pipeline code

texture_wrapping.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/texture_wrapping.png

Render pipeline code

filter_linear.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/filter_linear.png

filter_nearest.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/filter_nearest.png

texture_filtering.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/texture_filtering.png

Render pipeline code

mipmaps.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/mipmaps.png

Render pipeline code

• Texture
• Read the data from file input stream.
• Generate the texture object.
• Bind and setup the texture object.

Render pipeline code

• Shader program
• Build the individual shader in render pipeline.
• Build a shader program to link the shader.

Render pipeline code

• Vertex Shader
• Must have
• Tessellation
• Optional
• Geometric Shader
• Optional
• Fragment Shader
• Optional, but recommended

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Render pipeline code

• Build the individual shader in render pipeline.
• Vertex Shader
• Fragment Shader

Render pipeline code

• Build-in Variable
• Vary from shader to shader.
• We will discuss the gl_Position only.
• Full list
• https://www.khronos.org/opengl/wiki/Built-in_Variable_(GLSL)

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Render pipeline code

• gl_Position
• The output position of the current vertex.
• Vertex shader output
• Geometry shader input/output

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Render pipeline code

• Vertex shader
• Specify the OpenGL version.
• Specify the generic vertex attribute array.
• Specify the output structure for next pipeline stage.

vertex_attribute_pointer.png – LearnOpenGL (Joey de Vries) – CC BY 4.0

https://learnopengl.com/img/getting-started/vertex_attribute_pointer_interleaved.png

Render pipeline code

• Vertex shader
• [Optional] Specify a variable for shader object.
• Operate the vertex attribute.

Render pipeline code

• Fragment shader
• Specify the OpenGL version.
• Specify the output structure for next stage.
• Specify the input structure from previous stage.
• [Optional] Specify a variable for shader object.
• Determine the color.

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Render pipeline code

• Build a shader program to link the shader.
• Remember to read the code via file input stream.

Render pipeline code

• Compile shader
• Create a shader object to catch the shader.
• Compile the shader.
• Check the compile status.

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Render pipeline code

• Create shader program
• Create a shader program object to link the shader.
• Check the link status.

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Render pipeline code

• Render the mesh in render loop.
• Render the mesh in the window repeatedly.

Render pipeline code

• Render the mesh in render loop.
• Clear the render buffer.
• Use the proper shader program.
• Bind the correct vertex array object and texture.
• Set the shader variables.
• Draw the mesh.