Who invented opengl

Once we have downloaded the SOIL library, we extract the file to a location on the hard disk. Next, we set up the include and library paths in the Visual Studio environment. Of course, the path for your system will be different than mine but these are the folders that the directories should point to.

These steps will help us to set up our development environment. For all of the recipes in this book, Visual Studio Professional version is used.

Since there are a myriad of development environments, to make it easier for users on other platforms, we have provided premake script files as well.

Let us setup the development environment using the following steps:. We first create a new Win32 Console Application project as shown in the preceding screenshot.

We set up an empty Win32 project as shown in the following screenshot:. Next, we set up the include and library paths for the project by going into the Project menu and selecting project Properties. This opens a new dialog box. Similarly, in the Library Directories , add the path to the lib subfolder of GLEW and freeglut libraries as shown in the following screenshot:.

Next, we add a new. This is the main source file of our project. These lines are the include files that we will add to all of our projects. In Visual Studio, we can add the required linker libraries in two ways. The first way is through the Visual Studio environment by going to the Properties menu item in the Project menu.

This opens the project's property pages. In the configuration properties tree, we collapse the Linker subtree and click on the Input item. The first field in the right pane is Additional Dependencies. We can add the linker library in this field as shown in the following screenshot:. The second way is to add the glew This can be achieved by adding the following pragma :.

The next line is the using directive to enable access to the functions in the std namespace. This is not mandatory but we include this here so that we do not have to prefix std:: to any standard library function from the iostream header file. The next lines define the width and height constants which will be the screen resolution for the window.

After these declarations, there are five function definitions. The OnInit function is used for initializing any OpenGL state or object, OnShutdown is used to delete an OpenGL object, OnResize is used to handle the resize event, OnRender helps to handle the paint event, and main is the entry point of the application. We start with the definition of the main function.

We pass the command line arguments to this function from our entry point. Next, we set up the display mode for our application. In this case, we request the GLUT framework to provide support for a depth buffer, double buffering that is a front and a back buffer for smooth, flicker-free rendering , and the format of the frame buffer to be RGBA that is with red, green, blue, and alpha channels. For example, if we want to create an OpenGL v4.

Next, the context flags are specified:. In OpenGL v4. However, they are removed from the core profile. In our case, we will request a forward compatible core profile which means that we will not have any fixed function OpenGL functionality available. Next, we initialize the GLEW library.

The glewExperimental global switch allows the GLEW library to report an extension if it is supported by the hardware but is unsupported by the experimental or pre-release drivers. After the function is initialized, the GLEW diagnostic information such as the GLEW version, the graphics vendor, the OpenGL renderer, and the shader language version are printed to the standard output.

Finally, we call our initialization function OnInit and then attach our uninitialization function OnShutdown as the glutCloseFunc method—the close callback function which will be called when the window is about to close.

Next, we attach our display and reshape function to their corresponding callbacks. The main function is terminated with a call to the glutMainLoop function which starts the application's main loop. For this simple example, we set the clear color to red R:1, G:0, B:0, A The first three are the red, green, and blue channels and the last is the alpha channel which is used in alpha blending.

The only other function defined in this simple example is the OnRender function, which is our display callback function that is called on the paint event. This function first clears the color and depth buffers to the clear color and clear depth values respectively. Similar to the color buffer, there is another buffer called the depth buffer. Its clear value can be set using the glClearDepth function. It is used for hardware based hidden surface removal.

It simply stores the depth of the nearest fragment encountered so far. The incoming fragment's depth value overwrites the depth buffer value based on the depth clear function specified for the depth test using the glDepthFunc function.

By default the depth value gets overwritten if the current fragment's depth is lower than the existing depth in the depth buffer. The glutSwapBuffers function is then called to set the current back buffer as the current front buffer that is shown on screen. This call is required in a double buffered OpenGL application. Running the code gives us the output shown in the following screenshot.

We will now have a look at how to set up shaders. Shaders are special programs that are run on the GPU. There are different shaders for controlling different stages of the programmable graphics pipeline. In the modern GPU, these include the vertex shader which is responsible for calculating the clip-space position of a vertex , the tessellation control shader which is responsible for determining the amount of tessellation of a given patch , the tessellation evaluation shader which computes the interpolated positions and other attributes on the tessellation result , the geometry shader which processes primitives and can add additional primitives and vertices if needed , and the fragment shader which converts a rasterized fragment into a colored pixel and a depth.

The modern GPU pipeline highlighting the different shader stages is shown in the following figure. Since the steps involved in shader handling as well as compiling and attaching shaders for use in OpenGL applications are similar, we wrap these steps in a simple class we call GLSLShader. We first declare the constructor and destructor which initialize the member variables.

The next two functions, Use and UnUse functions bind and unbind the program. Two std::map datastructures are used. To make it convenient to access the attribute and uniform locations from their maps , we declare the two indexers.

For attributes, we overload the square brackets [] whereas for uniforms, we overload the parenthesis operation. Finally, we define a function DeleteShaderProgram for deletion of the shader program object. Following the function declarations are the member fields. Note that the above steps are required at initialization only. At the rendering step, we access uniform s , if we have uniforms that change each frame for example, the modelview matrices. In a typical OpenGL shader application, the shader specific functions and their sequence of execution are as follows:.

Execution of the above four functions creates a shader object. After the shader object is created, a shader program object is created using the following set of functions in the following sequence:. After the shader program object has been created, we can set the program for execution on the GPU.

This process is called shader binding. To enable communication between the application and the shader, there are two different kinds of fields available in the shader. The first are the attributes which may change during shader execution across different shader stages. All per-vertex attributes fall in this category. The second are the uniforms which remain constant throughout the shader execution.

Typical examples include the modelview matrix and the texture samplers. In the GLSLShader class, for convenience, we store the locations of attributes and uniforms in two separate std::map objects. In cases where there is an error in the compilation or linking stage, the shader log is printed to the console. AddUniform "MVP".

This function adds the uniform's location to the map. Then when we want to access the uniform, we directly call shader "MVP" and it returns the location of our uniform.

We will now put the GLSLShader class to use by implementing an application to render a simple colored triangle on screen. For this recipe, we assume that the reader has created a new empty Win32 project with OpenGL 3. This macro checks the current error bit for any error which might be raised by passing invalid arguments to an OpenGL function, or when there is some problem with the OpenGL state machine.

For any such error, this macro traps it and generates a debug assertion signifying that the OpenGL state machine has some error. In normal cases, no assertion should be raised, so adding this macro helps to identify errors.

Since this macro calls glGetError inside a debug assert, it is stripped in the release build. Now we will look at the different transformation stages through which a vertex goes, before it is finally rendered on screen. Initially, the vertex position is specified in what is called the object space. This space is the one in which the vertex location is specified for an object.

We apply modeling transformation to the object space vertex position by multiplying it with an affine matrix for example, a matrix for scaling, rotating, translating, and so on. This brings the object space vertex position into world space. OpenGL stores the modeling and viewing transformations in a single modelview matrix. The view space positions are then projected by using a projection transformation which brings the position into clip space.

The clip space positions are then normalized to get the normalized device coordinates which have a canonical viewing volume coordinates are [-1,-1,0] to [1,1,1] in x, y, and z coordinates respectively.

Let us start this recipe using the following steps:. Create the geometry and topology. We will store the attributes together in an interleaved vertex format, that is, we will store the vertex attributes in a struct containing two attributes, position and color. Store the geometry and topology in the buffer object s. The stride parameter controls the number of bytes to jump to reach the next element of the same attribute. For the interleaved format, it is typically the size of our vertex struct in bytes, that is, sizeof Vertex.

Set up the rendering code to bind the GLSLShader shader, pass the uniforms, and then draw the geometry. The first line in the shader signifies the GLSL version of the shader. Starting from OpenGL v3. So for OpenGL v3. In addition, since we are interested in the core profile, we add another keyword following the version number to signify that we have a core profile shader.

Another important thing to note is the layout qualifier. This is used to bind a specific integral attribute index to a given per-vertex attribute. While we can give the attribute locations in any order, for all of the recipes in this book the attribute locations are specified starting from 0 for position, 1 for normals, 2 for texture coordinates, and so on.

The layout location qualifier makes the glBindAttribLocation call redundant as the location index specified in the shader overrides any glBindAttribLocation call. The vertex shader simply outputs the input per-vertex color to the output vSmoothColor. Such attributes that are interpolated across shader stages are called varying attributes.

It also calculates the clip space position by multiplying the per-vertex position vVertex with the combined modelview projection MVP matrix. By prefixing smooth to the output attribute, we tell the GLSL shader to do smooth perspective-correct interpolation for the attribute to the next stage of the pipeline.

The other qualifiers usable are flat and noperspective. When no qualifier is specified the default interpolation qualifier is smooth.

The fragment shader writes the input color vSmoothColor to the frame buffer output vFragColor. In the simple triangle demo application code, we store the GLSLShader object reference in the global scope so that we can access it in any function we desire. We modify the OnInit function by adding the following lines:. The first two lines create the GLSL shader of the given type by reading the contents of the file with the given filename.

In all of the recipes in this book, the vertex shader files are stored with a. Next, the program is bound and then the locations of attributes and uniforms are stored. We pass two attributes per-vertex, that is vertex position and vertex color.

In order to facilitate the data transfer to the GPU, we create a simple Vertex struct as follows:. Next, we create an array of three vertices in the global scope. In addition, we store the triangle's vertex indices in the indices global array. Later we initialize these two arrays in the OnInit function. The first vertex is assigned the red color, the second vertex is assigned the green color, and the third vertex is assigned the blue color. Next, the vertex positions are given. The first vertex is assigned an object space position of -1,-1, 0 , the second vertex is assigned 0,1,0 , and the third vertex is assigned 1,-1,0.

For this simple demo, we use an orthographic projection for a view volume of -1,1,-1,1. Finally, the three indices are given in a linear order. In order to facilitate the handling of buffer object s during rendering, we use a vertex array object VAO.

This object stores references to buffer objects that are bound after the VAO is bound. The buffer objects are generated using the glGenBuffers function. The first parameter for both of these functions is the total number of objects required, and the second parameter is the reference to where the object handle is stored.

These functions are called in the OnInit function. Next, we pass the data to the buffer object by using the glBufferData function. The second parameter is the size of the vertex array we will push to the GPU memory.

The third parameter is the pointer to the start of the CPU memory. As mobile, lower power devices starting appearing on the market, a 3D graphics solution was desired for these devices. Full details can be found here. If software developers can write programs that run on multiple platforms, they have the potential to make greater profits from their efforts.

The added features to HTML make it possible to write web applications that are sophisticated, powerful, and cross platform. What is WebGL? WebGL is integrated completely into all the web standards of the browser allowing GPU accelerated usage of physics and image processing and effects as part of the web page canvas. And since basically all devices today have a GPU, this means that you can write one program that will execute on basically all computer devices in existence today — and tomorrow — thanks to the HTML 5.

Bottom line: if you understand how to program WebGL programs, you will understand basic computer graphics programming for all computing devices. Learn WebGL. Table of Contents Book Index. Anisotropic Filtering. OpenGL Contexts can be created that do not report errors of any kind. More operations for Atomic Counters. Adds new modes to glBeginConditionalRender which invert condition used to determine whether to draw or not.

Provides control over the spacial granularity at which the underlying implementation computes derivatives. Allows modifying and querying object state without binding objects.

Relaxes the restrictions on rendering to a currently bound texture and provides a mechanism to avoid read-after-write hazards. Immutable storage for buffer objects, including the ability to use buffers while they are mapped. Direct clearing of a texture image. A number of enhancements to layout qualifiers: Integer layout qualifiers can take any constant expression , not just integer literals.

Explicit layout requests for buffer-backed interface blocks. In-shader specification of transform feedback parameters. Bind an array of objects of the same type to a sequential range of indexed binding targets in one call. Values from Query Objects values can be written to a buffer object instead of directly to client memory.

A special clamping mode that doubles the size of the texture in each dimension, mirroring it exactly once in the negative texture coordinate directions.

One of the stencil-only image formats can be used for textures, and 8-bit stencil is a required format. GLSL multidimensional arrays. Clear Buffer Objects to specific values, ala memset. Arbitrary image copying. Specifying uniform locations in a shader. Layer and viewport indices available from the fragment shader. Rendering to a Framebuffer Object that has no attachments.

Generalized queries for information about Image Formats. Texture , buffer object , and framebuffer invalidation. Issuing multiple indirect rendering commands from a single drawing command. Improved API for getting info about program object interfaces. Get size of images from GLSL. Buffer object read-write access from shader , via a uniform-block style mechanism.

Buffer Textures can now be bound to a range of a buffer object rather than the whole thing. GLSL can detect the available mipmap pyramid of a sampler or image. Immutable storage for multisample textures.