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#include "ui/image_renderer.h"
#include "core/log.h"
#include <glad/gl.h>
#include <filesystem>
#include <fstream>
#include <iterator>
#include <string>
#ifndef HSDBG_ASSET_DIR
#define HSDBG_ASSET_DIR ""
#endif
namespace Hsdbg
{
namespace
{
auto read_file(const std::filesystem::path& path) -> std::string
{
std::ifstream file(path);
if (!file.is_open())
{
Log::error("image_renderer: could not open '{}'", path.string());
return {};
}
return std::string(std::istreambuf_iterator<char>(file),
std::istreambuf_iterator<char>());
}
auto compile(unsigned int type, const char* source) -> unsigned int
{
const unsigned int shader = glCreateShader(type);
glShaderSource(shader, 1, &source, nullptr);
glCompileShader(shader);
int ok = 0;
glGetShaderiv(shader, GL_COMPILE_STATUS, &ok);
if (ok == 0)
{
char log[512];
glGetShaderInfoLog(shader, sizeof(log), nullptr, log);
Log::error("image_renderer: shader compile failed: {}", log);
glDeleteShader(shader);
return 0;
}
return shader;
}
}
ImageRenderer::~ImageRenderer()
{
shutdown();
}
auto ImageRenderer::init() -> bool
{
const std::filesystem::path assets(HSDBG_ASSET_DIR);
const std::string vertex_source = read_file(assets / "texture.vert");
const std::string fragment_source = read_file(assets / "texture.glsl");
if (vertex_source.empty() || fragment_source.empty())
return false;
const unsigned int vertex = compile(GL_VERTEX_SHADER, vertex_source.c_str());
const unsigned int fragment = compile(GL_FRAGMENT_SHADER, fragment_source.c_str());
if (vertex == 0 || fragment == 0)
return false;
m_program = glCreateProgram();
glAttachShader(m_program, vertex);
glAttachShader(m_program, fragment);
glBindAttribLocation(m_program, 0, "a_position");
glBindAttribLocation(m_program, 1, "a_uv");
glLinkProgram(m_program);
glDeleteShader(vertex);
glDeleteShader(fragment);
int ok = 0;
glGetProgramiv(m_program, GL_LINK_STATUS, &ok);
if (ok == 0)
{
char log[512];
glGetProgramInfoLog(m_program, sizeof(log), nullptr, log);
Log::error("image_renderer: program link failed: {}", log);
glDeleteProgram(m_program);
m_program = 0;
return false;
}
m_texture_uniform = glGetUniformLocation(m_program, "u_texture");
glGenVertexArrays(1, &m_vao);
glGenBuffers(1, &m_vbo);
glBindVertexArray(m_vao);
glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 24, nullptr, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 4,
reinterpret_cast<void*>(0));
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 4,
reinterpret_cast<void*>(sizeof(float) * 2));
glBindVertexArray(0);
return true;
}
auto ImageRenderer::shutdown() -> void
{
if (m_vbo != 0)
glDeleteBuffers(1, &m_vbo);
if (m_vao != 0)
glDeleteVertexArrays(1, &m_vao);
if (m_program != 0)
glDeleteProgram(m_program);
m_vbo = 0;
m_vao = 0;
m_program = 0;
}
auto ImageRenderer::draw(unsigned int texture,
float x0, float y0, float x1, float y1,
int framebuffer_width, int framebuffer_height) -> void
{
if (m_program == 0 || texture == 0 || framebuffer_width <= 0 || framebuffer_height <= 0)
return;
const auto to_ndc_x = [&](float pixel) {
return pixel / static_cast<float>(framebuffer_width) * 2.0f - 1.0f;
};
const auto to_ndc_y = [&](float pixel) {
return 1.0f - pixel / static_cast<float>(framebuffer_height) * 2.0f;
};
const float left = to_ndc_x(x0);
const float right = to_ndc_x(x1);
const float top = to_ndc_y(y0);
const float bottom = to_ndc_y(y1);
// two triangles; the u coordinate runs 1 -> 0 left-to-right so the image
// is mirrored horizontally, and v (0,0) stays at the top to match how the
// texture was uploaded (stb hands back the first row as the top)
const float vertices[24] = {
left, top, 1.0f, 0.0f,
left, bottom, 1.0f, 1.0f,
right, bottom, 0.0f, 1.0f,
left, top, 1.0f, 0.0f,
right, bottom, 0.0f, 1.0f,
right, top, 0.0f, 0.0f,
};
glViewport(0, 0, framebuffer_width, framebuffer_height);
glDisable(GL_DEPTH_TEST);
glDisable(GL_SCISSOR_TEST);
glDisable(GL_CULL_FACE);
glEnable(GL_BLEND);
glBlendEquation(GL_FUNC_ADD);
glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glUseProgram(m_program);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glUniform1i(m_texture_uniform, 0);
glBindVertexArray(m_vao);
glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
glDrawArrays(GL_TRIANGLES, 0, 6);
glBindVertexArray(0);
glBindTexture(GL_TEXTURE_2D, 0);
glUseProgram(0);
}
}
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