devices/VirtualCamera/util/EglProgram.cc

/*
 * Copyright (C) 2023 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// #define LOG_NDEBUG 0
#define LOG_TAG "EglProgram"
#include "EglProgram.h"

#include <array>

#include "EglUtil.h"
#include "GLES/gl.h"
#include "GLES2/gl2.h"
#include "log/log.h"

namespace android {
namespace services {
namespace virtualcamera {

namespace {

const char* kIdentityVertexShader = R"(
    attribute vec4 vPosition;
    void main() {
      gl_Position = vPosition;
    })";

const char* kJuliaFractalFragmentShader = R"(
    precision mediump float;
    uniform vec2 uResolution;
    uniform vec2 uC;
    uniform vec2 uUV;
    const float kIter = 64.0;

    vec2 imSq(vec2 n){
      return vec2(pow(n.x,2.0)-pow(n.y,2.0), 2.0*n.x*n.y);
    }

    float julia(vec2 n, vec2 c) {
      vec2 z = n;
      for (float i=0.0;i<kIter; i+=1.0) {
        z = imSq(z) + c;
        if (length(z) > 2.0) return i/kIter;
      }
      return kIter;
    }

    void main() {
      vec2 uv = vec2(gl_FragCoord.x / uResolution.x - 0.5, gl_FragCoord.y / uResolution.y - 0.5);
      float juliaVal = julia(uv * 4.0, uC);
      gl_FragColor = vec4( juliaVal,uUV.x,uUV.y,0.0);
    })";

constexpr int kCoordsPerVertex = 3;
const std::array<float, 12> kSquareCoords{-1.f, 1.0f, 0.0f,   // top left
                                          -1.f, -1.f, 0.0f,   // bottom left
                                          1.0f, -1.f, 0.0f,   // bottom right
                                          1.0f, 1.0f, 0.0f};  // top right

const std::array<uint8_t, 6> kDrawOrder{0, 1, 2, 0, 2, 3};

GLuint compileShader(GLenum shaderType, const char* src) {
  GLuint shader = glCreateShader(shaderType);
  if (shader == 0) {
    ALOGE("glCreateShader(shaderType=%x) error: %#x",
          static_cast<unsigned int>(shaderType), glGetError());
    return 0;
  }

  glShaderSource(shader, 1, &src, NULL);
  glCompileShader(shader);

  GLint compiled = 0;
  glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
  if (!compiled) {
    ALOGE("Compile of shader type %d failed", shaderType);
    GLint infoLen = 0;
    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
    if (infoLen) {
      char* buf = new char[infoLen];
      if (buf) {
        glGetShaderInfoLog(shader, infoLen, NULL, buf);
        ALOGE("Compile log: %s", buf);
        delete[] buf;
      }
    }
    glDeleteShader(shader);
    return 0;
  }
  return shader;
}

}  // namespace

EglProgram::~EglProgram() {
  if (mProgram) {
    glDeleteProgram(mProgram);
  }
}

bool EglProgram::initialize(const char* vertexShaderSrc,
                            const char* fragmentShaderSrc) {
  GLuint vertexShaderId = compileShader(GL_VERTEX_SHADER, vertexShaderSrc);
  if (checkEglError("compileShader(vertex)")) {
    return false;
  }
  GLuint fragmentShaderId = compileShader(GL_FRAGMENT_SHADER, fragmentShaderSrc);
  if (checkEglError("compileShader(fragment)")) {
    return false;
  }

  GLuint programId = glCreateProgram();

  glAttachShader(programId, vertexShaderId);
  glAttachShader(programId, fragmentShaderId);
  glLinkProgram(programId);

  GLint linkStatus = GL_FALSE;
  glGetProgramiv(programId, GL_LINK_STATUS, &linkStatus);
  if (linkStatus != GL_TRUE) {
    ALOGE("glLinkProgram failed");
    GLint bufLength = 0;
    glGetProgramiv(programId, GL_INFO_LOG_LENGTH, &bufLength);
    if (bufLength) {
      char* buf = new char[bufLength];
      if (buf) {
        glGetProgramInfoLog(programId, bufLength, NULL, buf);
        ALOGE("Link log: %s", buf);
        delete[] buf;
      }
    }
    glDeleteProgram(programId);
    return false;
  }

  mProgram = programId;

  return true;
}

EglTestPatternProgram::EglTestPatternProgram() {
  if (initialize(kIdentityVertexShader, kJuliaFractalFragmentShader)) {
    ALOGV("Successfully initialized EGL shaders for test pattern program.");
  } else {
    ALOGE("Test pattern EGL shader program initialization failed.");
  }
}

bool EglTestPatternProgram::draw(int width, int height, int frameNumber) {
  glViewport(0, 0, static_cast<GLsizei>(width), static_cast<GLsizei>(height));
  checkEglError("glViewport");

  // Load compiled shader.
  glUseProgram(mProgram);
  checkEglError("glUseProgram");

  // Compute point in complex plane corresponding to fractal for this frame number.
  float time = float(frameNumber) / 120.0f;
  const std::complex<float> c(std::sin(time) * 0.78f, std::cos(time) * 0.78f);

  // Pass uniform values to the shader.
  int resolutionHandle = glGetUniformLocation(mProgram, "uResolution");
  checkEglError("glGetUniformLocation -> uResolution");
  glUniform2f(resolutionHandle, static_cast<float>(width),
              static_cast<float>(height));
  checkEglError("glUniform2f -> uResolution");

  // Pass "C" constant value determining the Julia set to the shader.
  int cHandle = glGetUniformLocation(mProgram, "uC");
  glUniform2f(cHandle, c.imag(), c.real());

  // Pass chroma value to the shader.
  int uvHandle = glGetUniformLocation(mProgram, "uUV");
  glUniform2f(uvHandle, (c.imag() + 1.f) / 2.f, (c.real() + 1.f) / 2.f);

  // Pass vertex array to draw.
  int positionHandle = glGetAttribLocation(mProgram, "vPosition");
  glEnableVertexAttribArray(positionHandle);

  // Prepare the triangle coordinate data.
  glVertexAttribPointer(positionHandle, kCoordsPerVertex, GL_FLOAT, false,
                        kSquareCoords.size(), kSquareCoords.data());

  // Draw triangle strip forming a square filling the viewport.
  glDrawElements(GL_TRIANGLES, kDrawOrder.size(), GL_UNSIGNED_BYTE,
                 kDrawOrder.data());
  if (checkEglError("glDrawElements")) {
    return false;
  }

  return true;
}

}  // namespace virtualcamera
}  // namespace services
}  // namespace android