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140 lines
4.4 KiB
C++
140 lines
4.4 KiB
C++
//
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// TextureTarget.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 07/02/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "TextureTarget.hpp"
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#include <cstdlib>
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#include <vector>
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using namespace OpenGL;
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TextureTarget::TextureTarget(GLsizei width, GLsizei height, GLenum texture_unit, GLint mag_filter) :
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width_(width),
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height_(height),
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texture_unit_(texture_unit) {
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glGenFramebuffers(1, &framebuffer_);
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glBindFramebuffer(GL_FRAMEBUFFER, framebuffer_);
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expanded_width_ = 1;
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while(expanded_width_ < width) expanded_width_ <<= 1;
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expanded_height_ = 1;
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while(expanded_height_ < height) expanded_height_ <<= 1;
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glGenTextures(1, &texture_);
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glActiveTexture(texture_unit);
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glBindTexture(GL_TEXTURE_2D, texture_);
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std::vector<uint8_t> blank_buffer(static_cast<size_t>(expanded_width_ * expanded_height_ * 4), 0);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, static_cast<GLsizei>(expanded_width_), static_cast<GLsizei>(expanded_height_), 0, GL_RGBA, GL_UNSIGNED_BYTE, blank_buffer.data());
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mag_filter);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture_, 0);
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if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
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throw ErrorFramebufferIncomplete;
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}
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TextureTarget::~TextureTarget() {
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glDeleteFramebuffers(1, &framebuffer_);
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glDeleteTextures(1, &texture_);
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if(drawing_vertex_array_) glDeleteVertexArrays(1, &drawing_vertex_array_);
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if(drawing_array_buffer_) glDeleteBuffers(1, &drawing_array_buffer_);
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}
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void TextureTarget::bind_framebuffer() {
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glBindFramebuffer(GL_FRAMEBUFFER, framebuffer_);
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glViewport(0, 0, width_, height_);
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}
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void TextureTarget::bind_texture() {
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glBindTexture(GL_TEXTURE_2D, texture_);
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}
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void TextureTarget::draw(float aspect_ratio) {
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if(!pixel_shader_) {
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const char *vertex_shader =
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"#version 150\n"
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"in vec2 texCoord;"
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"in vec2 position;"
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"out vec2 texCoordVarying;"
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"void main(void)"
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"{"
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"texCoordVarying = texCoord;"
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"gl_Position = vec4(position, 0.0, 1.0);"
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"}";
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const char *fragment_shader =
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"#version 150\n"
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"in vec2 texCoordVarying;"
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"uniform sampler2D texID;"
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"out vec4 fragColour;"
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"void main(void)"
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"{"
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"fragColour = texture(texID, texCoordVarying);"
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"}";
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pixel_shader_.reset(new Shader(vertex_shader, fragment_shader));
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pixel_shader_->bind();
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glGenVertexArrays(1, &drawing_vertex_array_);
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glGenBuffers(1, &drawing_array_buffer_);
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glBindVertexArray(drawing_vertex_array_);
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glBindBuffer(GL_ARRAY_BUFFER, drawing_array_buffer_);
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GLint position_attribute = pixel_shader_->get_attrib_location("position");
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GLint tex_coord_attribute = pixel_shader_->get_attrib_location("texCoord");
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glEnableVertexAttribArray(static_cast<GLuint>(position_attribute));
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glEnableVertexAttribArray(static_cast<GLuint>(tex_coord_attribute));
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const GLsizei vertex_stride = 4 * sizeof(GLfloat);
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glVertexAttribPointer((GLuint)position_attribute, 2, GL_FLOAT, GL_FALSE, vertex_stride, (void *)0);
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glVertexAttribPointer((GLuint)tex_coord_attribute, 2, GL_FLOAT, GL_FALSE, vertex_stride, (void *)(2 * sizeof(GLfloat)));
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GLint texIDUniform = pixel_shader_->get_uniform_location("texID");
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glUniform1i(texIDUniform, static_cast<GLint>(texture_unit_ - GL_TEXTURE0));
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}
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if(set_aspect_ratio_ != aspect_ratio) {
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set_aspect_ratio_ = aspect_ratio;
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float buffer[4*4];
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// establish texture coordinates
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buffer[2] = 0.0f;
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buffer[3] = 0.0f;
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buffer[6] = 0.0f;
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buffer[7] = static_cast<float>(height_) / static_cast<float>(expanded_height_);
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buffer[10] = static_cast<float>(width_) / static_cast<float>(expanded_width_);
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buffer[11] = 0.0f;
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buffer[14] = buffer[10];
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buffer[15] = buffer[7];
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// determine positions; rule is to keep the same height and centre
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float internal_aspect_ratio = static_cast<float>(width_) / static_cast<float>(height_);
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float aspect_ratio_ratio = internal_aspect_ratio / aspect_ratio;
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buffer[0] = -aspect_ratio_ratio; buffer[1] = -1.0f;
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buffer[4] = -aspect_ratio_ratio; buffer[5] = 1.0f;
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buffer[8] = aspect_ratio_ratio; buffer[9] = -1.0f;
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buffer[12] = aspect_ratio_ratio; buffer[13] = 1.0f;
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// upload buffer
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glBindBuffer(GL_ARRAY_BUFFER, drawing_array_buffer_);
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glBufferData(GL_ARRAY_BUFFER, sizeof(buffer), buffer, GL_STATIC_DRAW);
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}
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pixel_shader_->bind();
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glBindVertexArray(drawing_vertex_array_);
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glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
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}
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