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CLK/Outputs/OpenGL/Primitives/TextureTarget.cpp

184 lines
6.3 KiB
C++

//
// TextureTarget.cpp
// Clock Signal
//
// Created by Thomas Harte on 07/02/2016.
// Copyright 2016 Thomas Harte. All rights reserved.
//
#include "TextureTarget.hpp"
#include <cstdlib>
#include <vector>
#include <stdexcept>
using namespace Outputs::Display::OpenGL;
TextureTarget::TextureTarget(GLsizei width, GLsizei height, GLenum texture_unit, GLint mag_filter, bool has_stencil_buffer) :
width_(width),
height_(height),
texture_unit_(texture_unit) {
// Generate and bind a frame buffer.
test_gl(glGenFramebuffers, 1, &framebuffer_);
test_gl(glBindFramebuffer, GL_FRAMEBUFFER, framebuffer_);
// Round the width and height up to the next power of two.
expanded_width_ = 1;
while(expanded_width_ < width) expanded_width_ <<= 1;
expanded_height_ = 1;
while(expanded_height_ < height) expanded_height_ <<= 1;
// Generate a texture and bind it to the nominated texture unit.
test_gl(glGenTextures, 1, &texture_);
bind_texture();
// Set dimensions and set the user-supplied magnification filter.
test_gl(glTexImage2D, GL_TEXTURE_2D, 0, GL_RGBA, GLsizei(expanded_width_), GLsizei(expanded_height_), 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
test_gl(glTexParameteri, GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mag_filter);
test_gl(glTexParameteri, GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
// Set the texture as colour attachment 0 on the frame buffer.
test_gl(glFramebufferTexture2D, GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture_, 0);
// Also add a stencil buffer if requested.
if(has_stencil_buffer) {
test_gl(glGenRenderbuffers, 1, &renderbuffer_);
test_gl(glBindRenderbuffer, GL_RENDERBUFFER, renderbuffer_);
test_gl(glRenderbufferStorage, GL_RENDERBUFFER, GL_STENCIL_INDEX8, expanded_width_, expanded_height_);
test_gl(glFramebufferRenderbuffer, GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, renderbuffer_);
}
// Check for successful construction.
const auto framebuffer_status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if(framebuffer_status != GL_FRAMEBUFFER_COMPLETE) {
switch(framebuffer_status) {
case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT:
throw std::runtime_error("GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT");
case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER:
throw std::runtime_error("GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER");
case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER:
throw std::runtime_error("GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER");
case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT:
throw std::runtime_error("GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT");
case GL_FRAMEBUFFER_UNSUPPORTED:
throw std::runtime_error("GL_FRAMEBUFFER_UNSUPPORTED");
default:
throw std::runtime_error("Framebuffer status incomplete: " + std::to_string(framebuffer_status));
case 0:
test_gl_error();
break;
}
}
// Clear the framebuffer.
test_gl(glClear, GL_COLOR_BUFFER_BIT);
}
TextureTarget::~TextureTarget() {
glDeleteFramebuffers(1, &framebuffer_);
glDeleteTextures(1, &texture_);
if(renderbuffer_) glDeleteRenderbuffers(1, &renderbuffer_);
if(drawing_vertex_array_) glDeleteVertexArrays(1, &drawing_vertex_array_);
if(drawing_array_buffer_) glDeleteBuffers(1, &drawing_array_buffer_);
}
void TextureTarget::bind_framebuffer() {
test_gl(glBindFramebuffer, GL_FRAMEBUFFER, framebuffer_);
test_gl(glViewport, 0, 0, width_, height_);
}
void TextureTarget::bind_texture() const {
test_gl(glActiveTexture, texture_unit_);
test_gl(glBindTexture, GL_TEXTURE_2D, texture_);
}
void TextureTarget::draw(float aspect_ratio, float colour_threshold) const {
if(!pixel_shader_) {
const char *vertex_shader =
"#version 150\n"
"in vec2 texCoord;"
"in vec2 position;"
"out vec2 texCoordVarying;"
"void main(void)"
"{"
"texCoordVarying = texCoord;"
"gl_Position = vec4(position, 0.0, 1.0);"
"}";
const char *fragment_shader =
"#version 150\n"
"in vec2 texCoordVarying;"
"uniform sampler2D texID;"
"uniform float threshold;"
"out vec4 fragColour;"
"void main(void)"
"{"
"fragColour = clamp(texture(texID, texCoordVarying), threshold, 1.0);"
"}";
pixel_shader_ = std::make_unique<Shader>(vertex_shader, fragment_shader);
pixel_shader_->bind();
test_gl(glGenVertexArrays, 1, &drawing_vertex_array_);
test_gl(glGenBuffers, 1, &drawing_array_buffer_);
test_gl(glBindVertexArray, drawing_vertex_array_);
test_gl(glBindBuffer, GL_ARRAY_BUFFER, drawing_array_buffer_);
const GLint position_attribute = pixel_shader_->get_attrib_location("position");
const GLint tex_coord_attribute = pixel_shader_->get_attrib_location("texCoord");
test_gl(glEnableVertexAttribArray, GLuint(position_attribute));
test_gl(glEnableVertexAttribArray, GLuint(tex_coord_attribute));
const GLsizei vertex_stride = 4 * sizeof(GLfloat);
test_gl(glVertexAttribPointer, GLuint(position_attribute), 2, GL_FLOAT, GL_FALSE, vertex_stride, (void *)0);
test_gl(glVertexAttribPointer, GLuint(tex_coord_attribute), 2, GL_FLOAT, GL_FALSE, vertex_stride, (void *)(2 * sizeof(GLfloat)));
const GLint texIDUniform = pixel_shader_->get_uniform_location("texID");
test_gl(glUniform1i, texIDUniform, GLint(texture_unit_ - GL_TEXTURE0));
threshold_uniform_ = pixel_shader_->get_uniform_location("threshold");
}
if(set_aspect_ratio_ != aspect_ratio) {
set_aspect_ratio_ = aspect_ratio;
float buffer[4*4];
// establish texture coordinates
buffer[2] = 0.0f;
buffer[3] = 0.0f;
buffer[6] = 0.0f;
buffer[7] = float(height_) / float(expanded_height_);
buffer[10] = float(width_) / float(expanded_width_);
buffer[11] = 0.0f;
buffer[14] = buffer[10];
buffer[15] = buffer[7];
// determine positions; rule is to keep the same height and centre
float internal_aspect_ratio = float(width_) / float(height_);
float aspect_ratio_ratio = internal_aspect_ratio / aspect_ratio;
buffer[0] = -aspect_ratio_ratio; buffer[1] = -1.0f;
buffer[4] = -aspect_ratio_ratio; buffer[5] = 1.0f;
buffer[8] = aspect_ratio_ratio; buffer[9] = -1.0f;
buffer[12] = aspect_ratio_ratio; buffer[13] = 1.0f;
// upload buffer
test_gl(glBindBuffer, GL_ARRAY_BUFFER, drawing_array_buffer_);
test_gl(glBufferData, GL_ARRAY_BUFFER, sizeof(buffer), buffer, GL_STATIC_DRAW);
}
pixel_shader_->bind();
test_gl(glUniform1f, threshold_uniform_, colour_threshold);
test_gl(glBindVertexArray, drawing_vertex_array_);
test_gl(glDrawArrays, GL_TRIANGLE_STRIP, 0, 4);
}