From ca36e42922326a798c4fdd950b3630fe92522551 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Tue, 1 Nov 2022 01:23:43 +0000
Subject: Somewhat dirty but functional helper to save a texture

Useful for debugging and not much else.
---
 gfx/models/texture.cpp | 27 +++++++++++++++++++++++++++
 gfx/models/texture.h   |  3 +++
 2 files changed, 30 insertions(+)

(limited to 'gfx')

diff --git a/gfx/models/texture.cpp b/gfx/models/texture.cpp
index ab04f4f..ff38d0f 100644
--- a/gfx/models/texture.cpp
+++ b/gfx/models/texture.cpp
@@ -2,7 +2,9 @@
 #include "glArrays.h"
 #include <GL/glew.h>
 #include <cache.h>
+#include <fcntl.h>
 #include <gfx/image.h>
+#include <glm/geometric.hpp>
 #include <resource.h>
 #include <stb/stb_image.h>
 
@@ -36,3 +38,28 @@ Texture::bind(GLenum unit) const
 	glActiveTexture(unit);
 	glBindTexture(GL_TEXTURE_2D, m_texture);
 }
+
+void
+Texture::save(const glTexture & texture, const glm::ivec2 & size, const char * path)
+{
+	GLint drawFboId = 0, readFboId = 0;
+	glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &drawFboId);
+	glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &readFboId);
+	std::vector<unsigned char> buffer(static_cast<size_t>(size.x * size.y * 3));
+	{
+		glFrameBuffer tmp;
+		glBindFramebuffer(GL_FRAMEBUFFER, tmp);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
+		glReadPixels(0, 0, size.x, size.y, GL_BGR, GL_UNSIGNED_BYTE, buffer.data());
+	}
+	{
+		auto out = open(path, O_WRONLY | O_CREAT, 0660);
+		short TGAhead[] = {0, 2, 0, 0, 0, 0, static_cast<short>(size.x), static_cast<short>(size.y), 24};
+		std::ignore = write(out, &TGAhead, sizeof(TGAhead));
+		std::ignore = write(out, buffer.data(), buffer.size());
+		std::ignore = ftruncate(out, static_cast<off_t>(buffer.size() + sizeof(TGAhead)));
+		close(out);
+	}
+	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, static_cast<GLuint>(drawFboId));
+	glBindFramebuffer(GL_READ_FRAMEBUFFER, static_cast<GLuint>(readFboId));
+}
diff --git a/gfx/models/texture.h b/gfx/models/texture.h
index 2bbf1f4..09538b3 100644
--- a/gfx/models/texture.h
+++ b/gfx/models/texture.h
@@ -3,6 +3,7 @@
 #include <cache.h>
 #include <filesystem>
 #include <glArrays.h>
+#include <glm/fwd.hpp>
 
 // IWYU pragma: no_forward_declare Cache
 class Image;
@@ -17,6 +18,8 @@ public:
 
 	void bind(GLenum unit = GL_TEXTURE0) const;
 
+	static void save(const glTexture &, const glm::ivec2 & size, const char * path);
+
 private:
 	glTexture m_texture;
 };
-- 
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