/*
* Initalize OpenGL
*/
int gl2_init(int width, int height) {
GLenum error = GL_NO_ERROR;
glViewport(0, 0, width, height);
// Initialize the projection matrix
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// Multiply the current matrix with the orthographic matrix
glOrtho(0.f, width, height, 0.f, -1.f, 1.f);
// Initialize the modelview matrix
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Enable transparency
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
// Check for errors
error = glGetError();
if (error != GL_NO_ERROR) {
S2D_GL_PrintError("OpenGL initialization failed");
return 1;
} else {
return 0;
}
}
/*
* Creates a shader object, loads shader string, and compiles.
* Returns 0 if shader could not be compiled.
*/
GLuint S2D_GL_LoadShader(GLenum type, const GLchar *shaderSrc, char *shaderName) {
GLuint shader;
GLint compiled;
// Create the shader object
shader = glCreateShader(type);
if (shader == 0) {
S2D_GL_PrintError("Failed to create shader program");
return 0;
}
// Load the shader source
glShaderSource(shader, 1, &shaderSrc, NULL);
// Compile the shader
glCompileShader(shader);
// Check the compile status
glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
if (!compiled) {
GLint infoLen = 0;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
if (infoLen > 1) {
char *infoLog = malloc(sizeof(char) * infoLen);
glGetShaderInfoLog(shader, infoLen, NULL, infoLog);
printf("Error compiling shader \"%s\":\n%s\n", shaderName, infoLog);
free(infoLog);
}
glDeleteShader(shader);
return 0;
}
return shader;
}
/*
* Initalize OpenGL ES
*/
int S2D_gles_init(int width, int height, int s_width, int s_height) {
// Enable transparency
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
// Set the viewport
glViewport(0, 0, width, height);
// Vertex shader source string
GLchar vertexSource[] =
// uniforms used by the vertex shader
"uniform mat4 u_mvpMatrix;" // model view and projection matrix
// attributes input to the vertex shader
"attribute vec4 a_position;" // position value
"attribute vec4 a_color;" // input vertex color
"attribute vec2 a_texcoord;" // input texture
// varying variables, input to the fragment shader
"varying vec4 v_color;" // output vertex color
"varying vec2 v_texcoord;" // output texture
// main
"void main()"
"{"
" v_color = a_color;"
" v_texcoord = a_texcoord;"
" gl_Position = u_mvpMatrix * vec4(a_position.xyz, 1.0);"
"}";
// Fragment shader source string
GLchar fragmentSource[] =
"precision mediump float;"
// input vertex color from vertex shader
"varying vec4 v_color;"
"void main()"
"{"
" gl_FragColor = v_color;"
"}";
// Fragment shader source string for textures
GLchar texFragmentSource[] =
"precision mediump float;"
// input vertex color from vertex shader
"varying vec4 v_color;"
"varying vec2 v_texcoord;"
"uniform sampler2D texture;"
"void main()"
"{"
" gl_FragColor = texture(texture, v_texcoord) * v_color;"
"}";
// Load the vertex and fragment shaders
GLuint vertexShader = S2D_GL_LoadShader( GL_VERTEX_SHADER, vertexSource, "GLES Vertex");
GLuint fragmentShader = S2D_GL_LoadShader(GL_FRAGMENT_SHADER, fragmentSource, "GLES Fragment");
GLuint texFragmentShader = S2D_GL_LoadShader(GL_FRAGMENT_SHADER, texFragmentSource, "GLES Texture Fragment");
// Create the shader program object
shaderProgram = glCreateProgram();
// Check if program was created successfully
if (shaderProgram == 0) {
S2D_GL_PrintError("Failed to create shader program");
return GL_FALSE;
}
// Create the texture shader program object
texShaderProgram = glCreateProgram();
// Check if program was created successfully
if (texShaderProgram == 0) {
S2D_GL_PrintError("Failed to create shader program");
return GL_FALSE;
}
// Attach the shader objects to the program object
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glAttachShader(texShaderProgram, vertexShader);
glAttachShader(texShaderProgram, texFragmentShader);
// Associate user-defined attribute variables in the
// program object with the vertex attribute index
glBindAttribLocation(shaderProgram, 0, "a_position");
glBindAttribLocation(texShaderProgram, 0, "a_position");
// Link the shader program
glLinkProgram(shaderProgram);
glLinkProgram(texShaderProgram);
// Check if linked
S2D_gles_check_linked(shaderProgram, "shaderProgram");
S2D_gles_check_linked(texShaderProgram, "texShaderProgram");
// Compute scaling factors, if necessary
GLfloat scale_x = 1.0f;
GLfloat scale_y = 1.0f;
if (s_width != width) {
scale_x = (GLfloat)s_width / (GLfloat)width;
}
if (s_height != height) {
scale_y = (GLfloat)s_height / (GLfloat)height;
}
// Set orthographic projection matrix
S2D_GL_orthoMatrix[0] = 2.0f / ((GLfloat)width * scale_x);
S2D_GL_orthoMatrix[5] = -2.0f / ((GLfloat)height * scale_y);
// Use the program object
glUseProgram(shaderProgram);
GLuint mMvpLocation = glGetUniformLocation(shaderProgram, "u_mvpMatrix");
glUniformMatrix4fv(mMvpLocation, 1, GL_FALSE, S2D_GL_orthoMatrix);
// Use the texture program object
glUseProgram(texShaderProgram);
GLuint texmMvpLocation = glGetUniformLocation(texShaderProgram, "u_mvpMatrix");
glUniformMatrix4fv(texmMvpLocation, 1, GL_FALSE, S2D_GL_orthoMatrix);
// Clean up
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
glDeleteShader(texFragmentShader);
return GL_TRUE;
}
/*
* Initalize OpenGL ES
*/
int S2D_GLES_Init() {
// Enable transparency
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
// Vertex shader source string
GLchar vertexSource[] =
// uniforms used by the vertex shader
"uniform mat4 u_mvpMatrix;" // projection matrix
// attributes input to the vertex shader
"attribute vec4 a_position;" // position value
"attribute vec4 a_color;" // input vertex color
"attribute vec2 a_texcoord;" // input texture
// varying variables, input to the fragment shader
"varying vec4 v_color;" // output vertex color
"varying vec2 v_texcoord;" // output texture
"void main()"
"{"
" v_color = a_color;"
" v_texcoord = a_texcoord;"
" gl_Position = u_mvpMatrix * a_position;"
"}";
// Fragment shader source string
GLchar fragmentSource[] =
"precision mediump float;"
// input vertex color from vertex shader
"varying vec4 v_color;"
"void main()"
"{"
" gl_FragColor = v_color;"
"}";
// Fragment shader source string for textures
GLchar texFragmentSource[] =
"precision mediump float;"
// input vertex color from vertex shader
"varying vec4 v_color;"
"varying vec2 v_texcoord;"
"uniform sampler2D s_texture;"
"void main()"
"{"
" gl_FragColor = texture2D(s_texture, v_texcoord) * v_color;"
"}";
// Load the vertex and fragment shaders
GLuint vertexShader = S2D_GL_LoadShader( GL_VERTEX_SHADER, vertexSource, "GLES Vertex");
GLuint fragmentShader = S2D_GL_LoadShader(GL_FRAGMENT_SHADER, fragmentSource, "GLES Fragment");
GLuint texFragmentShader = S2D_GL_LoadShader(GL_FRAGMENT_SHADER, texFragmentSource, "GLES Texture Fragment");
// Triangle Shader //
// Create the shader program object
shaderProgram = glCreateProgram();
// Check if program was created successfully
if (shaderProgram == 0) {
S2D_GL_PrintError("Failed to create shader program");
return GL_FALSE;
}
// Attach the shader objects to the program object
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
// Link the shader program
glLinkProgram(shaderProgram);
// Check if linked
S2D_GL_CheckLinked(shaderProgram, "GLES shader");
// Get the attribute locations
positionLocation = glGetAttribLocation(shaderProgram, "a_position");
colorLocation = glGetAttribLocation(shaderProgram, "a_color");
// Texture Shader //
// Create the texture shader program object
texShaderProgram = glCreateProgram();
// Check if program was created successfully
if (texShaderProgram == 0) {
S2D_GL_PrintError("Failed to create shader program");
return GL_FALSE;
}
// Attach the shader objects to the program object
glAttachShader(texShaderProgram, vertexShader);
glAttachShader(texShaderProgram, texFragmentShader);
// Link the shader program
glLinkProgram(texShaderProgram);
// Check if linked
S2D_GL_CheckLinked(texShaderProgram, "GLES texture shader");
// Get the attribute locations
texPositionLocation = glGetAttribLocation(texShaderProgram, "a_position");
texColorLocation = glGetAttribLocation(texShaderProgram, "a_color");
texCoordLocation = glGetAttribLocation(texShaderProgram, "a_texcoord");
// Get the sampler location
samplerLocation = glGetUniformLocation(texShaderProgram, "s_texture");
// Clean up
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
glDeleteShader(texFragmentShader);
return GL_TRUE;
}
