src/utils/shader_util.c

/*
     File: shader_util.c
 Abstract: Functions that compile, link and validate shader programs.
  Version: 1.13

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 Original file modified by Belledonne Communications, Grenoble, France
 Copyright (C) 2017
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>

#include "shader_util.h"
#include "opengl_debug.h"

#define LogInfo printf
#define LogError printf

/* Compile a shader from the provided source(s) */
GLint glueCompileShader (const OpenGlFunctions *f, GLenum target, GLsizei count, const GLchar *sources, GLuint *shader) {
  GLint logLength, status;

  *shader = f->glCreateShader(target);
  f->glShaderSource(*shader, count, &sources, NULL);
  f->glCompileShader(*shader);

  f->glGetShaderiv(*shader, GL_INFO_LOG_LENGTH, &logLength);
  if (logLength > 0) {
    GLchar *log = (GLchar *)malloc(logLength);
    f->glGetShaderInfoLog(*shader, logLength, &logLength, log);
    LogInfo("Shader compile log:\n%s", log);
    free(log);
  }

  f->glGetShaderiv(*shader, GL_COMPILE_STATUS, &status);
  if (status == 0) {
    int i;

    LogError("Failed to compile shader:\n");
    for (i = 0; i < count; i++)
      LogInfo("%s", &sources[i]);
  }

  glError(f);

  return status;
}

/* Link a program with all currently attached shaders */
GLint glueLinkProgram (const OpenGlFunctions *f, GLuint program) {
  GLint logLength, status;

  f->glLinkProgram(program);
  f->glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logLength);
  if (logLength > 0) {
    GLchar *log = (GLchar *)malloc(logLength);
    f->glGetProgramInfoLog(program, logLength, &logLength, log);
    LogInfo("Program link log:\n%s", log);
    free(log);
  }

  f->glGetProgramiv(program, GL_LINK_STATUS, &status);
  if (status == 0)
    LogError("Failed to link program %d", program);

  glError(f);

  return status;
}

/* Validate a program (for i.e. inconsistent samplers) */
GLint glueValidateProgram (const OpenGlFunctions *f, GLuint program) {
  GLint logLength, status;

  f->glValidateProgram(program);
  f->glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logLength);
  if (logLength > 0) {
    GLchar *log = (GLchar *)malloc(logLength);
    f->glGetProgramInfoLog(program, logLength, &logLength, log);
    LogInfo("Program validate log:\n%s", log);
    free(log);
  }

  f->glGetProgramiv(program, GL_VALIDATE_STATUS, &status);
  if (status == 0)
    LogError("Failed to validate program %d", program);

  glError(f);

  return status;
}

/* Return named uniform location after linking */
GLint glueGetUniformLocation (const OpenGlFunctions *f, GLuint program, const GLchar *uniformName) {
  return f->glGetUniformLocation(program, uniformName);
}

/* Convenience wrapper that compiles, links, enumerates uniforms and attribs */
GLint glueCreateProgram (
  const OpenGlFunctions *f,
  const GLchar *vertSource,
  const GLchar *fragSource,
  GLsizei attribNameCt,
  const GLchar **attribNames,
  const GLint *attribLocations,
  GLsizei uniformNameCt,
  const GLchar **uniformNames,
  GLint *uniformLocations,
  GLuint *program
) {
  GLuint vertShader = 0, fragShader = 0, prog = 0, status = 1;
  GLint i;

  prog = f->glCreateProgram();

  status *= glueCompileShader(f, GL_VERTEX_SHADER, 1, vertSource, &vertShader);
  status *= glueCompileShader(f, GL_FRAGMENT_SHADER, 1, fragSource, &fragShader);
  f->glAttachShader(prog, vertShader);
  f->glAttachShader(prog, fragShader);

  for (i = 0; i < attribNameCt; i++) {
    if (strlen(attribNames[i]))
      f->glBindAttribLocation(prog, attribLocations[i], attribNames[i]);
  }

  status *= glueLinkProgram(f, prog);
  status *= glueValidateProgram(f, prog);

  if (status) {
    for (i = 0; i < uniformNameCt; i++) {
      if (strlen(uniformNames[i]))
        uniformLocations[i] = glueGetUniformLocation(f, prog, uniformNames[i]);
    }

    *program = prog;
  }

  if (vertShader)
    f->glDeleteShader(vertShader);
  if (fragShader)
    f->glDeleteShader(fragShader);

  glError(f);

  return status;
}