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/*
* Copyright 2016 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#import "RTCShader.h"
#if TARGET_OS_IPHONE
#import <OpenGLES/ES3/gl.h>
#else
#import <OpenGL/gl3.h>
#endif
#include <algorithm>
#include <array>
#include <memory>
#import "RTCOpenGLDefines.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
// Vertex shader doesn't do anything except pass coordinates through.
const char kRTCVertexShaderSource[] =
SHADER_VERSION
VERTEX_SHADER_IN " vec2 position;\n"
VERTEX_SHADER_IN " vec2 texcoord;\n"
VERTEX_SHADER_OUT " vec2 v_texcoord;\n"
"void main() {\n"
" gl_Position = vec4(position.x, position.y, 0.0, 1.0);\n"
" v_texcoord = texcoord;\n"
"}\n";
// Compiles a shader of the given `type` with GLSL source `source` and returns
// the shader handle or 0 on error.
GLuint RTCCreateShader(GLenum type, const GLchar *source) {
GLuint shader = glCreateShader(type);
if (!shader) {
return 0;
}
glShaderSource(shader, 1, &source, NULL);
glCompileShader(shader);
GLint compileStatus = GL_FALSE;
glGetShaderiv(shader, GL_COMPILE_STATUS, &compileStatus);
if (compileStatus == GL_FALSE) {
GLint logLength = 0;
// The null termination character is included in the returned log length.
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logLength);
if (logLength > 0) {
std::unique_ptr<char[]> compileLog(new char[logLength]);
// The returned string is null terminated.
glGetShaderInfoLog(shader, logLength, NULL, compileLog.get());
RTC_LOG(LS_ERROR) << "Shader compile error: " << compileLog.get();
}
glDeleteShader(shader);
shader = 0;
}
return shader;
}
// Links a shader program with the given vertex and fragment shaders and
// returns the program handle or 0 on error.
GLuint RTCCreateProgram(GLuint vertexShader, GLuint fragmentShader) {
if (vertexShader == 0 || fragmentShader == 0) {
return 0;
}
GLuint program = glCreateProgram();
if (!program) {
return 0;
}
glAttachShader(program, vertexShader);
glAttachShader(program, fragmentShader);
glLinkProgram(program);
GLint linkStatus = GL_FALSE;
glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
if (linkStatus == GL_FALSE) {
glDeleteProgram(program);
program = 0;
}
return program;
}
// Creates and links a shader program with the given fragment shader source and
// a plain vertex shader. Returns the program handle or 0 on error.
GLuint RTCCreateProgramFromFragmentSource(const char fragmentShaderSource[]) {
GLuint vertexShader = RTCCreateShader(GL_VERTEX_SHADER, kRTCVertexShaderSource);
RTC_CHECK(vertexShader) << "failed to create vertex shader";
GLuint fragmentShader =
RTCCreateShader(GL_FRAGMENT_SHADER, fragmentShaderSource);
RTC_CHECK(fragmentShader) << "failed to create fragment shader";
GLuint program = RTCCreateProgram(vertexShader, fragmentShader);
// Shaders are created only to generate program.
if (vertexShader) {
glDeleteShader(vertexShader);
}
if (fragmentShader) {
glDeleteShader(fragmentShader);
}
// Set vertex shader variables 'position' and 'texcoord' in program.
GLint position = glGetAttribLocation(program, "position");
GLint texcoord = glGetAttribLocation(program, "texcoord");
if (position < 0 || texcoord < 0) {
glDeleteProgram(program);
return 0;
}
// Read position attribute with size of 2 and stride of 4 beginning at the start of the array. The
// last argument indicates offset of data within the vertex buffer.
glVertexAttribPointer(position, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (void *)0);
glEnableVertexAttribArray(position);
// Read texcoord attribute with size of 2 and stride of 4 beginning at the first texcoord in the
// array. The last argument indicates offset of data within the vertex buffer.
glVertexAttribPointer(
texcoord, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (void *)(2 * sizeof(GLfloat)));
glEnableVertexAttribArray(texcoord);
return program;
}
BOOL RTCCreateVertexBuffer(GLuint *vertexBuffer, GLuint *vertexArray) {
#if !TARGET_OS_IPHONE
glGenVertexArrays(1, vertexArray);
if (*vertexArray == 0) {
return NO;
}
glBindVertexArray(*vertexArray);
#endif
glGenBuffers(1, vertexBuffer);
if (*vertexBuffer == 0) {
glDeleteVertexArrays(1, vertexArray);
return NO;
}
glBindBuffer(GL_ARRAY_BUFFER, *vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, 4 * 4 * sizeof(GLfloat), NULL, GL_DYNAMIC_DRAW);
return YES;
}
// Set vertex data to the currently bound vertex buffer.
void RTCSetVertexData(RTCVideoRotation rotation) {
// When modelview and projection matrices are identity (default) the world is
// contained in the square around origin with unit size 2. Drawing to these
// coordinates is equivalent to drawing to the entire screen. The texture is
// stretched over that square using texture coordinates (u, v) that range
// from (0, 0) to (1, 1) inclusive. Texture coordinates are flipped vertically
// here because the incoming frame has origin in upper left hand corner but
// OpenGL expects origin in bottom left corner.
std::array<std::array<GLfloat, 2>, 4> UVCoords = {{
{{0, 1}}, // Lower left.
{{1, 1}}, // Lower right.
{{1, 0}}, // Upper right.
{{0, 0}}, // Upper left.
}};
// Rotate the UV coordinates.
int rotation_offset;
switch (rotation) {
case RTCVideoRotation_0:
rotation_offset = 0;
break;
case RTCVideoRotation_90:
rotation_offset = 1;
break;
case RTCVideoRotation_180:
rotation_offset = 2;
break;
case RTCVideoRotation_270:
rotation_offset = 3;
break;
}
std::rotate(UVCoords.begin(), UVCoords.begin() + rotation_offset,
UVCoords.end());
const GLfloat gVertices[] = {
// X, Y, U, V.
-1, -1, UVCoords[0][0], UVCoords[0][1],
1, -1, UVCoords[1][0], UVCoords[1][1],
1, 1, UVCoords[2][0], UVCoords[2][1],
-1, 1, UVCoords[3][0], UVCoords[3][1],
};
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(gVertices), gVertices);
}
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