refactor export equirectangular

src/canvas_layer.cpp

@@ -1,8 +1,74 @@
 #include "pch.h"
 #include "canvas_layer.h"
+#include "app.h"
+#include "rtt.h"
 
 uint32_t Layer::s_count = 0;
 
+TextureCube Layer::gen_cube()
+{
+    TextureCube ret;
+    App::I->render_task([&]
+    {
+        ret.create(w);
+        ret.bind();
+        for (int i = 0; i < 6; i++)
+        {
+            m_rtt[i].bindFramebuffer();
+            glCopyTexSubImage2D(TextureCube::m_faces_map[i], 0, 0, 0, 0, 0, w, w);
+            m_rtt[i].unbindFramebuffer();
+        }
+    });
+    return ret;
+}
+
+Texture2D Layer::gen_equirect()
+{
+    Texture2D ret;
+    
+    App::I->render_task([&]
+    {
+        gl_state gl;
+        gl.save();
+
+        TextureCube cube;
+        RTT latlong;
+
+        cube = gen_cube();
+        latlong.create(w * 4, h * 2);
+        ret.create(w * 4, h * 2);
+
+        glDisable(GL_BLEND);
+
+        latlong.bindFramebuffer();
+
+        latlong.clear({ 0, 1, 1, 1 });
+
+        glViewport(0, 0, latlong.getWidth(), latlong.getHeight());
+
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, cube.m_cubetex_id);
+
+        ShaderManager::use(kShader::Equirect);
+        ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
+        ShaderManager::u_int(kShaderUniform::Tex, 0);
+        Canvas::I->m_sampler.bind(0);
+        Canvas::I->m_plane.draw_fill();
+
+        ret.bind();
+        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, latlong.getWidth(), latlong.getHeight());
+
+        latlong.unbindFramebuffer();
+
+        latlong.destroy();
+        cube.destroy();
+
+        gl.restore();
+    });
+
+    return ret;
+}
+
 void Layer::Snapshot::create(int w, int h)
 {
     width = w;