Opengl es 2.0 sample program how to#
Opengl es 2.0 sample program code#

Because Cocos2d 2.0 is built on OpenGL ES 2.0, it has already done much of this work for us.

Shader programs need to be written to properly setup the graphics pipeline to enable OpenGL ES 2.0 drawing.

GlDrawArrays(GL_TRIANGLE_STRIP, 0, dynamicVertCount) Ĭocos2d 2.0 makes custom drawing with OpenGL ES 2.o easy. GlVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, dynamicVertColors) GlEnableVertexAttribArray(kCCVertexAttribFlag_Color) Pass the colors of the vertices to draw to OpenGL GlVertexAttribPointer(kCCVertexAttrib_Position, 3, GL_FLOAT, GL_FALSE, 0, dynamicVerts) GlEnableVertexAttribArray(kCCVertexAttribFlag_Position)

Tell OpenGL ES 2.0 to use the shader program assigned in the init of this node. Enable the needed vertex attributes.ĬcGLEnableVertexAttribs( kCCVertexAttribFlag_Position | kCCVertexAttribFlag_Color ) Further detail about this important function can be found here and lots of other details about OpenGL ES 2.0 can be found at The Khronos Group site.

Opengl es 2.0 sample program code#

GlVertexAttributePointer is called to specify the location and format of the data that will be used to define the vertices and colors in the code below. In this sample program, an array of a C structures where each structure contains three floating point values for the x,y,z coordinates of each vertex is used to define the vertices and an array of the Cocoos2d data type ccColor4B which is a C structure of four GLbytes is used to define the red, green, blue, and alpha color of each vertex.Ĥ) Override the draw method with your custom drawing code that tells OpenGL ES 2.0 which shader program to use and what geometry data to draw. Self.shaderProgram = programForKey:kCCShader_PositionColor] ģ) Build your data structures that define the geometry that will be drawn. The instance variable shaderProgram exists in the CCNode class in Cocos2d 2.0. Must define what shader program OpenGL ES 2.0 should use. To keep things simple, you can use one of the shader programs from Cocos2d’s CCShaderCache, or if for more advanced and interesting effects you can experiment with creating your own shader programs. The basic process of setting up a CCNode subclass to perform custom drawing is the following:Ģ) Assign a shader program to the CCNode shaderProgram property. The CCNode class contains the draw method that should be overridden to perform custom OpenGL ES 2.0 drawing. To get started with Custom OpenGL ES 2.0 drawing in Cocos2d 2.0, it all starts with creating a subclass of CCNode. The following is an image showing what is seen when the app is run. When the project is run, a blue-green background gradient is created using a GL_TRIANGLE_STRIP draw technique and a simulated sound wave is animated using the GL_LINE_STRIP drawing technique. The sample project was created by starting with the basic Coco2d 2.0 template and then a CCNode subclass with custom OpenGL ES 2.0 drawing was implemented.

Opengl es 2.0 sample program how to#

This article is an introduction to how to use OpenGL ES 2.0 to draw basic things such as a sound wave, the rolling hills of games like Tiny Wings, Enduro Extreme Trials, SnowXross 2, and many other effects.ĭownload: A sample Xcode project that was created for this article can be download here. But sometimes custom OpenGL drawing is required to achieve a desired graphical effect in a game. A developer could build many games with Cocos2d 2.0 without ever having to directly use or understand OpenGL ES 2.0. Cocos2d 2.0 is a flexible game engine that leverages OpenGL ES 2.0 to render graphics.