//Original source code found at : book, iPhone 3D Programming 2010 by O'Reilly Media, Inc.

#if !defined(IOS) && !defined(ANDROID)

#error "Not supported platform!"

#else

#include <gles2.h>

#include <gles2ext.h>

#ifdef IOS

GLuint renderbuffer,framebuffer;

#endif

GLuint simpleProgram;

struct Vertex

};

const Vertex Vertices[6]=

{

{{-0.5,-0.866},{1,1,0.5f,1}},

{{0.5,-0.866},{1,1,0.5f,1}},

{{0,1},{1,1,0.5f,1}},

{{-0.5,-0.866},{0.5f,0.5f,0.5f,1}},

{{0.5,-0.866},{0.5f,0.5f,0.5f,1}},

{{0,-0.4f},{0.5f,0.5f,0.5f,1}},

};

const char *SimpleVertexShader=

"attribute vec4 Position;"

"attribute vec4 SourceColor;"

"varying vec4 DestinationColor;"

"uniform mat4 Projection;"

"uniform mat4 Modelview;"

"void main(void)"

"{"

" DestinationColor=SourceColor;"

" gl_Position=Projection*Modelview*Position;"

"}";

const char *SimpleFragmentShader=

"varying lowp vec4 DestinationColor;"

"void main(void)"

"{"

" gl_FragColor=DestinationColor;"

"}";

void ApplyOrtho(float maxX,float maxY) const

{

float a=1.0f/maxX;

float b=1.0f/maxY;

float ortho[16]=

{

a,0,0,0,

0,b,0,0,

0,0,-1,0,

0,0,0,1

};

GLint projectionUniform=glGetUniformLocation(simpleProgram,"Projection");

glUniformMatrix4fv(projectionUniform,1,0,&ortho[0]);

}

GLuint BuildShader(const char *source,GLenum shaderType) const

{

GLuint shaderHandle=glCreateShader(shaderType);

glShaderSource(shaderHandle,1,&source,0);

glCompileShader(shaderHandle);

GLint compileSuccess;

glGetShaderiv(shaderHandle,GL_COMPILE_STATUS,&compileSuccess);

if(compileSuccess==GL_FALSE)

{

GLchar messages[256];

glGetShaderInfoLog(shaderHandle,sizeof(messages),0,&messages[0]);

printf("compile glsl error : %s\n",messages);

}

return shaderHandle;

}

GLuint BuildProgram(const char *vShader,const char *fShader) const

{

GLuint vertexShader=BuildShader(vShader,GL_VERTEX_SHADER);

GLuint fragmentShader=BuildShader(fShader,GL_FRAGMENT_SHADER);

GLuint programHandle=glCreateProgram();

glAttachShader(programHandle,vertexShader);

glAttachShader(programHandle,fragmentShader);

glLinkProgram(programHandle);

GLint linkSuccess;

glGetProgramiv(programHandle,GL_LINK_STATUS,&linkSuccess);

if(linkSuccess==GL_FALSE)

{

GLchar messages[256];

glGetProgramInfoLog(programHandle,sizeof(messages),0,&messages[0]);

printf("compile glsl error : %s\n",messages);

}

return programHandle;

}

//OpenGLES2 handlers : init , final , update , render , touch-input

void on_GLES2_Init(int view_w,int view_h)

{

#ifdef IOS

glGenRenderbuffers(1,&renderbuffer);

glBindRenderbuffer(GL_RENDERBUFFER,renderbuffer);

glGenFramebuffers(1,&framebuffer);

glBindFramebuffer(GL_FRAMEBUFFER,framebuffer);

glFramebufferRenderbuffer(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,

GL_RENDERBUFFER,renderbuffer);

#endif

simpleProgram=BuildProgram(SimpleVertexShader,SimpleFragmentShader);

glUseProgram(simpleProgram);

}

void on_GLES2_Final()

{

if(simpleProgram)

glDeleteProgram(simpleProgram);

simpleProgram=0;

}

void on_GLES2_Size(int view_w,int view_h)

{

glViewport(0,0,view_w,view_h);

ApplyOrtho(2,3);

}

void on_GLES2_Update(float timeStep_sec)

{

}

void on_GLES2_Render()

{

glClearColor(0.5f,0.5f,0.5f,1);

glClear(GL_COLOR_BUFFER_BIT);

float modelViewMatrix[16]=

{

1,0,0,0,

0,1,0,0,

0,0,1,0,

0,0,0,1

};

GLint modelviewUniform=glGetUniformLocation(simpleProgram,"Modelview");

glUniformMatrix4fv(modelviewUniform,1,0,&modelViewMatrix[0]);

GLuint positionSlot=glGetAttribLocation(simpleProgram,"Position");

GLuint colorSlot=glGetAttribLocation(simpleProgram,"SourceColor");

glEnableVertexAttribArray(positionSlot);

glEnableVertexAttribArray(colorSlot);

GLsizei stride=sizeof(Vertex);

const GLvoid *pCoords=&Vertices[0].Position[0];

const GLvoid *pColors=&Vertices[0].Color[0];

glVertexAttribPointer(positionSlot,2,GL_FLOAT,GL_FALSE,stride,pCoords);

glVertexAttribPointer(colorSlot,4,GL_FLOAT,GL_FLOAT,stride,pColors);

GLsizei vertexCount=sizeof(Vertices)/sizeof(Vertex);

glDrawArrays(GL_TRIANGLES,0,vertexCount);

glDisableVertexAttribArray(positionSlot);

glDisableVertexAttribArray(colorSlot);

}

void on_GLES2_TouchBegin(float x,float y)

{

printf("on_GLES2_TouchBegin(x=%f,y=%f);\n",x,y);

}

void on_GLES2_TouchEnd(float x,float y)

{

printf("on_GLES2_TouchEnd(x=%f,y=%f);\n",x,y);

}

void on_GLES2_TouchMove(float prev_x,float prev_y,float x,float y)

{

printf("on_GLES2_TouchMove(prev_x=%f,prev_y=%f,x=%f,y=%f);\n",

prev_x,prev_y,x,y);

}

#ifdef IOS

void on_GLES2_DeviceRotate(int orientation)

{

printf("on_GLES2_DeviceRotate(orientation=%d);\n",orientation);

}

#endif

#endif