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OPENGL GAME DEVELOPMENT BY EXAMPLE PDF

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OpenGL Game Development By Example - Sample Chapter - Free download as PDF File .pdf), Text File .txt) or read online for free. Chapter No. 2 Your point of. OpenGL is one of the most popular rendering SDKs used to develop games. OpenGL has been used to create everything from 3D masterpieces running on. DOWNLOAD PDF .. Using Primitives: Triangles and Quads Example Attributes. n the spring of , we finished writing OpenGL Game Programming.


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He co-authored the first edition of Beginning OpenGL Game Programming, Chapter 5—The code is the same except for the manual extensions example. OpenGL Game Development By Example Robert Madsen, Stephen Madsen . By Example by Robert Madsen, Stephen Madsen Free PDF d0wnl0ad, audio. real-world example of developing an actual 3D game. By the end of the .. OpenGL's greatest strength lies in its availability with different computer systems. An.

Chapter 2, Your Point of View, introduces you to the first project in the bookcreating a 2D platform game.

The first step in this project will be to define the type of view that is required by OpenGL, and render the background of the game. Chapter 3, A Matter of Character, covers the creation of sprites that move on the screen. Chapter 4, Control Freak, teaches you how to build an input system that will allow you to control the main character and other aspects of the game.

You will also create a basic user interface that allows you to start the game and navigate to various options. Chapter 5, Hit and Run, covers collision detection.

You will learn how to stop the character from falling through the ground, how to land on objects, and how to detect whether enemies have hit you or have been hit by player weapons. By the end of this chapter, you will be able to play the game for the first time.

Preface Chapter 6, Polishing the Silver, covers the topics that make a game presentable but are often overlooked by novice developers. You will learn how to implement a scoring system, game over and game won scenarios, and simple level progression. This chapter will conclude the 2D project of the book. Chapter 7, Audio Adrenaline, guides you through implementing sound effects and music in the game. We will provide links to some audio files that you can use in your game.

Chapter 8, Expanding Your Horizons, will start the second project of the booka 3D first-person space shooter. At the end of this chapter you will have created a new project, starting the framework for a 3D game. Chapter 9, Super Models, introduces you to the concepts of 3D art and modeling, and then guides you through the process of loading 3D models into the game environment. Although you will be able try your hand at creating a 3D model, the resources that are required for the game will be provided online.

OpenGL Game Development By Example

Chapter 10, Expanding Space, expands on many of the concepts that were covered in the 2D segment of the book and applies them to a 3D world. Movement and collision detection are revamped to take this new dimension into consideration. The ideas behind Vulkan are similar to those of Direct3D 12 and Metal , but Vulkan has the advantage of being fully cross-platform and allows you to develop for Windows, Linux and Android at the same time.

However, the price you pay for these benefits is that you have to work with a significantly more verbose API. Every detail related to the graphics API needs to be set up from scratch by your application, including initial frame buffer creation and memory management for objects like buffers and texture images.

The graphics driver will do a lot less hand holding, which means that you will have to do more work in your application to ensure correct behavior. The takeaway message here is that Vulkan is not for everyone. It is targeted at programmers who are enthusiastic about high performance computer graphics, and are willing to put some work in. If you are more interested in game development, rather than computer graphics, then you may wish to stick to OpenGL or Direct3D, which will not be deprecated in favor of Vulkan anytime soon.

Another alternative is to use an engine like Unreal Engine or Unity , which will be able to use Vulkan while exposing a much higher level API to you. It will not explain the math behind perspective projection, for example. See this online book for a great introduction of computer graphics concepts. There is also an alternative version of this tutorial available for Rust developers. To make it easier to follow along for developers using other programming languages, and to get some experience with the base API we'll be using the original C API to work with Vulkan.

The purpose of all the smaller steps will make more sense after you've understood their basic role in the whole picture. The update function initializes the render buffer, draws objects to the render buffer, and then transfers the contents of the render buffer to the screen. In a game running at 60 frames per second, this entire operation will happen 60 times a second! Stretching your point Let's see how easy it will be to modify GLFun to draw other objects.

This time we will draw two lines. Add the following function to your code just under the drawPoints function: Your Point of View glVertex2f 0.

Next, go to the update function and replace drawPoints with a call to drawLines. The new update function will look like this: You will notice that there are four glVertex calls. Each pair of vertices sets the beginning and ending points of a line. As there are four points defined, the result is that two lines are drawn. Getting primitive Basic objects, such as points and lines, are called primitives.

It would be pretty difficult to create everything out of points and lines, so OpenGL defines other primitive shapes that you can use to create more complicated objects. In this section, we will dig a little under the hood and find out how OpenGL actually creates more realistic images on your screen. It may surprise you that a single, geometric figure is used to create everything from the simplest to the most complex graphics.

So, roll up your sleeves and get ready to get a little greasy. A triangle by any other name Have you ever seen a geodesic dome? Although the dome appears to be spherical, it is actually built out of a combination of triangles. It turns out that triangles are very easy to put together in such a way that you can add a slight amount of curvature to the object. Each triangle can be attached at a slight angle to the others, allowing you to create a dome made out of flat triangles.

Also, consider this: The basic unit that is used to draw all modern graphics is the humble triangle. Graphic cards have been specifically engineered to be able to draw trianglesreally small trianglesreally fast.

Beginning OpenGL Game Programming, Second Edition

A typical graphics card can draw millions of triangles every second. Higher end cards reach billions of triangles per second.

Remember when we drew points and lines earlier? Each point had one vertex, and each line had two vertices. Of course, each triangle has three vertices. A primitive example It's time to take a look at some code in action.

Add the following code after the drawLines function in the GLFun project: Then change the middle line of the update function to call drawSolidTriangle: You may notice a similarity between the code for drawSolidTriangle and drawPoints.

Look closely at the code, and you will see that the three glVertex functions define the same three points.

OpenGL is one of the most popular rendering SDKs used to

However, in this case we told OpenGL to draw triangles, not points. You should also take a look at the code and make sure you understand why the triangle is rendered blue. Let's take one more example. Add the following code below the drawSolidTriangle function: Be sure to change the middle line in update to call drawGradientTriangle: You will immediately notice that this triangle is filled with a gradient instead of a solid color.

If you look closely at the code, you will see that a different color is being set for each vertex. OpenGL then takes care of interpolating the colors between each vertex. From triangles to models Triangles can be put together in an infinite number of ways to form almost any shape imaginable.

It is important to understand that triangles are just geometry. Triangles are used to build the shape of your object. We call these shapes models. Building a model using a single triangle at a time would be very time consuming, so 3D graphics programs, such as Maya and Blender, allow you to create models out more complex shapes which are themselves built out of triangles.

These models can then be loaded into your game and rendered by OpenGL. OpenGL literally sends a the list of points to form these triangles directly to the video card, which then creates and image out of them on the screen. We will see this process in action when we begin to deal with 3D game design. Introducing textures Images in games are called textures. Textures allow us to use real world images to paint our world.

Think about what it would take to create a dirt road. You could either color the triangles in exactly the right way to make the overall scene look like dirt, or you could apply an actual image that is, a texture of dirt to the triangles. Which of these do you think would look more realistic? Using textures to fill the triangles Let's say that you are going to paint your bedroom.

You can either use paint to color the walls, or you could buy some wallpaper and put that on your walls. Using images to add color to our triangles is pretty much like using wallpaper to color our bedroom walls. The image is applied to the triangle, giving it a more complex appearance than what could be created by color alone:. When we want to get really tricky, we use textures to fill the inside of our triangles instead of colors.

A marble texture has been applied to the triangle in the preceding image. You could imagine using this technique to create a marble floor. Remember the car we were working with before? It didn't look much like a triangle, did it? In fact, many real-world objects look more like rectangles than triangles:. It turns out that that all the textures that we use in games are actually rectangles.

Imagine that the car that we have been dealing with is actually embedded inside an invisible rectangle, depicted in the following image as light gray:.

Most graphic programs use a checkerboard background to indicate the areas of the image that are transparent. Using rectangles for all of our shapes solves one big problem that you might not have thought of earlier.

If you recall, it was very important to position the car at exactly 5, 5. To do so, we decided to place the bottom-left corner of the car at point 5, 5.

Looking at the car, it is actually a little difficult to figure out exactly where the bottom-left corner would be.

Is it the lower left corner of the bumper, the tire, or somewhere else? By embedding the car inside of a rectangle, as we just discussed, the problem is immediately solved.

A matter of reference When working with a texture, it is very important to know what point is being used as a reference, usually known as the pivot point. In the following images, a black dot is used to represent the pivot point. The pivot point affects two critical issues. First, the pivot point determines exactly where the image will be placed on the screen. Second, the pivot point is the point on which the image will pivot when rotated.

Compare the two scenarios depicted in the following images:. The pivot point for the car in the preceding image has been set to the bottom-left corner of the image.

The car has been rotated 90 degrees counter-clockwise. The pivot point for the car in the preceding image has been set to the center of the image. Notice how the pivot point affects not only how the car is rotated but also its final position in relation to its original position after the rotation is completed. Hanging out in the quad So, are you confused yet?

First, I tell you that the most basic shape used to create images is a triangle, and then I tell you that all textures are actually rectangles. Which one is it? Just then, your high-school geometry teacher silently walks into the room, goes up to the chalkboard that just magically appeared on your wall, and draws something like the following diagram:.

Of course! You suddenly realize that two triangles can be fit together to form a rectangle. In fact, this arrangement is so useful that we have given it a name: When it comes to 2D graphics, the quad is the king.

Coding the quad It's time to take a look at some code. As usual, change the middle line in update to call drawQuad. Run the program, and you will get a pretty green square, er quad! It's important to note that the points are defined in order starting from the upper-left corner and then moving counterclockwise in order.

The order that the points are defined in is known as winding. By default, a counter-clockwise winding tells OpenGL that the side facing out is the side that is considered the front. This helps determine, among other things, whether this face should be lit, and it becomes even more significant when we begin working in 3D.

Rendering a texture Rendering a texture consist of two steps: Our final achievement in this chapter will be to modify GLFun so that it will render a texture using a quad.

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Loading the texture Our first step is to create a function to load a texture. As it turns out, this isn't all that easy.

So, I'm going to give you the code for a function that loads a bit BMP file, and we'll treat it like a black box that you can use in your own code. Add this code to the top of your existing GLFun code: GLuint texture; pragma warning disable: Add these lines of code to initGL: We are not going to dissect this piece of code line by line.

In brief, it opens the image file, extracts the first 54 bytes of the file the bmp header data , and stores the rest of the file as image data. Of course, replace car. Ensure that you have placed the appropriate graphic files in the source code folder. Texture wrapping In order to display a texture on the screen, OpenGL maps the texture onto another primitive.

This process is known as texture wrapping. As textures are rectangular, it makes sense to map the texture onto a quad. The following image shows a texture the way that OpenGL sees it: The upper-left is texture coordinate 0, 0.

The lower-right is texture coordinate 1, 1. You should be able to identify the texture coordinates of the other corners. It might make it easier to conceptualize OpenGL numbers if you convert them to percentage, where 0 is zero percent and 1 is percent.

For example, you can think of the lower-left corner as being zero percent of the width of the texture and one-hundred percent of the height of the texture. In order to render a texture, we overlay it or wrap it onto a quad. So, let's say we have the following quad defined:. In its simplest form, texture wrapping is the process of mapping the corners of a texture to the corners of a quad.

You will see texture wrapping also referred to as uv wrapping.This is done through the use of custom programs that actually execute on the graphics hardware. Working with Arrays. The specular term is affected by the position of both the light and the eye.

This parameter allows you to attach some additional data to a window. Preface Chapter 6, Polishing the Silver, covers the topics that make a game presentable but are often overlooked by novice developers.

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