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145 lines
4.2 KiB
C++
145 lines
4.2 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 <math.h>
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using namespace OpenGL;
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TextureTarget::TextureTarget(GLsizei width, GLsizei height, GLenum texture_unit) :
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_width(width),
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_height(height),
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_pixel_shader(nullptr),
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_drawing_vertex_array(0),
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_drawing_array_buffer(0),
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_set_aspect_ratio(0.0f),
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_texture_unit(texture_unit)
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{
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glGenFramebuffers(1, &_framebuffer);
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glBindFramebuffer(GL_FRAMEBUFFER, _framebuffer);
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_expanded_width = 1 << (GLsizei)ceil(log2(width));
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_expanded_height = 1 << (GLsizei)ceil(log2(height));
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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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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)_expanded_width, (GLsizei)_expanded_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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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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{
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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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{
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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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{
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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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{
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if(!_pixel_shader)
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{
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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 = std::unique_ptr<Shader>(new Shader(vertex_shader, fragment_shader, nullptr));
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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 positionAttribute = _pixel_shader->get_attrib_location("position");
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GLint texCoordAttribute = _pixel_shader->get_attrib_location("texCoord");
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glEnableVertexAttribArray((GLuint)positionAttribute);
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glEnableVertexAttribArray((GLuint)texCoordAttribute);
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const GLsizei vertexStride = 4 * sizeof(GLfloat);
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glVertexAttribPointer((GLuint)positionAttribute, 2, GL_FLOAT, GL_FALSE, vertexStride, (void *)0);
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glVertexAttribPointer((GLuint)texCoordAttribute, 2, GL_FLOAT, GL_FALSE, vertexStride, (void *)(2 * sizeof(GLfloat)));
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GLint texIDUniform = _pixel_shader->get_uniform_location("texID");
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glUniform1i(texIDUniform, (GLint)(_texture_unit - GL_TEXTURE0));
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}
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if(_set_aspect_ratio != aspect_ratio)
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{
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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] = (float)_height / (float)_expanded_height;
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buffer[10] = (float)_width / (float)_expanded_width;
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buffer[11] = 0;
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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 = (float)_width / (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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