demo/src/shader.cpp

#include "shader.h"
#include <iostream>

BEGIN_NAMESPACE

void check_compile_error(GLuint shaderId) {
    GLint isCompiled = 0;
    glGetShaderiv(shaderId, GL_COMPILE_STATUS, &isCompiled);
    if (isCompiled == GL_FALSE) {
        GLint maxLength = 0;
        glGetShaderiv(shaderId, GL_INFO_LOG_LENGTH, &maxLength);

        //The maxLength includes the NULL character
        char errorLog[maxLength];
        glGetShaderInfoLog(shaderId, maxLength, &maxLength, &errorLog[0]);

        LOG(ERROR) << "Shader compile error: (" << isCompiled << ") - " << std::string(errorLog);

        //Provide the infolog in whatever manor you deem best.
        //Exit with failure.
        glDeleteShader(shaderId); //Don't leak the shader.
    } else {
        LOG(INFO) << "Shader successfully compiled";
    }
}

void check_link_error(GLuint program_id) {
    GLint is_linked = 0;
    glGetShaderiv(program_id, GL_LINK_STATUS, &is_linked);
    if (is_linked == GL_FALSE) {
        GLint maxLength = 0;
        glGetShaderiv(program_id, GL_INFO_LOG_LENGTH, &maxLength);

        //The maxLength includes the NULL character
        char errorLog[maxLength];
        glGetShaderInfoLog(program_id, maxLength, &maxLength, &errorLog[0]);

        LOG(ERROR) << "Shader program link error: " << "(" << is_linked << ") - " << std::string(errorLog);

        //Provide the info log in whatever manner you deem best.
        //Exit with failure.
        glDeleteShader(program_id); //Don't leak the program shader.
    } else {
        LOG(INFO) << "Shader program successfully linked";
    }
}


shader::shader(const char *vs_content, const char *ps_content) {
    shader_ids[0] = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(shader_ids[0], 1, &vs_content, nullptr);
    glCompileShader(shader_ids[0]);
    check_compile_error(shader_ids[0]);

    shader_ids[1] = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(shader_ids[1], 1, &ps_content, nullptr);
    glCompileShader(shader_ids[1]);
    check_compile_error(shader_ids[1]);

    program_id = glCreateProgram();
    glAttachShader(program_id, shader_ids[0]);
    glAttachShader(program_id, shader_ids[1]);

    // TODO Adrian: these should come from an external enumeration
    glBindAttribLocation(program_id, 0, "position");
    glBindAttribLocation(program_id, 1, "normal");
    glBindAttribLocation(program_id, 2, "texCoords");

    glLinkProgram(program_id);
    check_link_error(program_id);

    glUseProgram(program_id);
}

shader::~shader() {
    glDetachShader(program_id, shader_ids[0]);
    glDetachShader(program_id, shader_ids[1]);

    glDeleteShader(shader_ids[0]);
    glDeleteShader(shader_ids[1]);

    glDeleteProgram(program_id);
}

void shader::use() const {
    glUseProgram(program_id);
}

void shader::unuse() const {
    glUseProgram(0);
}

int shader::getUniform(const char *uniformName) {
    if (uniform_cache.count(uniformName) == 0) {
        uniform_cache[uniformName] = glGetUniformLocation(program_id, uniformName);
    }
    return uniform_cache[uniformName];
}

void shader::setMatrix3Uniform(float *matrix, const char *uniformName) {
    GLint location = getUniform(uniformName);
    if (location != -1)
        glUniformMatrix3fv(location, 1, false, matrix);
}

void shader::setMatrix4Uniform(float *matrix, const char *uniformName) {
    GLint location = getUniform(uniformName);
    if (location != -1)
        glUniformMatrix4fv(location, 1, false, matrix);
}

void shader::setVec3Uniform(float *value, const char *uniformName) {
    GLint location = getUniform(uniformName);
    if (location != -1)
        glUniform3fv(location, 1, value);
}

void shader::setVec4Uniform(float *value, const char *uniformName) {
    GLint location = getUniform(uniformName);
    if (location != -1)
        glUniform4fv(location, 1, value);
}

void shader::setIntUniform(int value, const char *uniformName) {
    GLint location = getUniform(uniformName);
    if (location != -1)
        glUniform1i(location, value);
}

void shader::setFloatUniform(float value, const char *uniformName) {
    GLint location = getUniform(uniformName);
    if (location != -1)
        glUniform1f(location, value);
}


END_NAMESPACE