From 6b27f014fc0eeadf27298e4811409415144be965 Mon Sep 17 00:00:00 2001 From: Paul Gardiner Date: Mon, 17 Oct 2016 06:46:26 +0100 Subject: [PATCH] Correct the Skybox fov (#16655) * Remove undrawn quads from the skybox mesh CCSkybox had been implemented using a combination of two inconsistent techniques. The rendering was being achieved via use of the vertex shader's inherent support for cubemaps. That technique requires only a single screen-covering quad, but the implemtation defined a cube. Defining a cube mesh would be appropriate if one were simply mapping the cubemap's 6 textures to faces, but is unnecessary if using the shader's cubemap feature. Not only was the use of a cube mesh unnecessary, but the particular way the cube was defined and used meant that only one face would ever contribute to the rendering. One of the other faces would always be culled and the other four would be viewed edge on, mapping the the infinitesimally thin lines defining the edges of the screen. This commit simply removes the never-rendered faces, and adds comments explaining the technique. * Within test code, remove setScale calls applied to skyboxes. A Skybox is defined in such a way that it's position, rotation and scaling has no effect on it's rendering, so setScale has no effect. The calls are removed from test code to avoid confusing anyone using it as a template for their own programs. * Make the Skybox correctly account for the camera's fov The Skybox does not use the model/view and projection matricies. Instead a single quad that maps exactly to the screen is rendered and the camera's world matrix is passed into a shader that renders using cubemap lookups. The way that works hardwires the fov to 90deg in both the horizontal and vertical. That shows up particularly badly when the camera is pointed directly downwards and rotated: the image deforms as it rotates. This commit corrects the problem by using scaling factors from the camera's projection matrix to prescale the matrix passed into the shader. --- cocos/3d/CCSkybox.cpp | 39 +++++++++++++------ .../Classes/Scene3DTest/Scene3DTest.cpp | 1 - .../js-tests/src/Sprite3DTest/Sprite3DTest.js | 1 - .../lua-tests/src/Scene3DTest/Scene3DTest.lua | 1 - .../src/Sprite3DTest/Sprite3DTest.lua | 1 - 5 files changed, 28 insertions(+), 15 deletions(-) diff --git a/cocos/3d/CCSkybox.cpp b/cocos/3d/CCSkybox.cpp index 197358a56b..35542cb01a 100644 --- a/cocos/3d/CCSkybox.cpp +++ b/cocos/3d/CCSkybox.cpp @@ -109,11 +109,30 @@ void Skybox::initBuffers() glGenVertexArrays(1, &_vao); GL::bindVAO(_vao); } + // The skybox is rendered using a purpose-built shader which makes use of + // the shader language's inherent support for cubemaps. Hence there is no + // need to build a cube mesh. All that is needed is a single quad that + // covers the entire screen. The vertex shader will draw the appropriate + // view of the cubemap onto that quad. + // + // The vertex shader does not apply either the model/view matrix or the + // projection matrix, so the appropriate quad is one with unit coordinates + // in the x and y dimensions. Such a quad will exacly cover the screen. + // To ensure that the skybox is rendered behind all other objects, z needs + // to be 1.0, but the vertex shader overwrites z to 1.0, so - for the sake + // of z-buffering - it is unimportant what we set it to for the verticies + // of the quad. + // + // The quad vertex positions are also used in deriving a direction + // vector for the cubemap lookup. We choose z = -1 which matches the + // negative-z pointing direction of the camera and gives a field of + // view of 90deg in both x and y, if not otherwise adjusted. That fov + // is then adjusted to exactly match the camera by applying a prescaling + // to the camera's world transformation before sending it to the shader. // init vertex buffer object Vec3 vexBuf[] = { - Vec3(1, -1, 1), Vec3(1, 1, 1), Vec3(-1, 1, 1), Vec3(-1, -1, 1), Vec3(1, -1, -1), Vec3(1, 1, -1), Vec3(-1, 1, -1), Vec3(-1, -1, -1) }; @@ -122,13 +141,7 @@ void Skybox::initBuffers() glBufferData(GL_ARRAY_BUFFER, sizeof(vexBuf), vexBuf, GL_STATIC_DRAW); // init index buffer object - const unsigned char idxBuf[] = { 2, 1, 0, 3, 2, 0, // font - 1, 5, 4, 1, 4, 0, // right - 4, 5, 6, 4, 6, 7, // back - 7, 6, 2, 7, 2, 3, // left - 2, 6, 5, 2, 5, 1, // up - 3, 0, 4, 3, 4, 7 // down - }; + const unsigned char idxBuf[] = {0, 1, 2, 0, 2, 3}; glGenBuffers(1, &_indexBuffer); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBuffer); @@ -157,13 +170,17 @@ void Skybox::onDraw(const Mat4& transform, uint32_t flags) auto camera = Camera::getVisitingCamera(); Mat4 cameraModelMat = camera->getNodeToWorldTransform(); + Mat4 projectionMat = camera->getProjectionMatrix(); + // Ignore the translation + cameraModelMat.m[12] = cameraModelMat.m[13] = cameraModelMat.m[14] = 0; + // prescale the matrix to account for the camera fov + cameraModelMat.scale(1 / projectionMat.m[0], 1 / projectionMat.m[5], 1.0); auto state = getGLProgramState(); state->apply(transform); Vec4 color(_displayedColor.r / 255.f, _displayedColor.g / 255.f, _displayedColor.b / 255.f, 1.f); state->setUniformVec4("u_color", color); - cameraModelMat.m[12] = cameraModelMat.m[13] = cameraModelMat.m[14] = 0; state->setUniformMat4("u_cameraRot", cameraModelMat); glEnable(GL_DEPTH_TEST); @@ -195,7 +212,7 @@ void Skybox::onDraw(const Mat4& transform, uint32_t flags) glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBuffer); } - glDrawElements(GL_TRIANGLES, (GLsizei)36, GL_UNSIGNED_BYTE, nullptr); + glDrawElements(GL_TRIANGLES, (GLsizei)6, GL_UNSIGNED_BYTE, nullptr); if (Configuration::getInstance()->supportsShareableVAO()) { @@ -207,7 +224,7 @@ void Skybox::onDraw(const Mat4& transform, uint32_t flags) glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); } - CC_INCREMENT_GL_DRAWN_BATCHES_AND_VERTICES(1, 8); + CC_INCREMENT_GL_DRAWN_BATCHES_AND_VERTICES(1, 4); CHECK_GL_ERROR_DEBUG(); } diff --git a/tests/cpp-tests/Classes/Scene3DTest/Scene3DTest.cpp b/tests/cpp-tests/Classes/Scene3DTest/Scene3DTest.cpp index d11a8c60fa..c041e857f5 100644 --- a/tests/cpp-tests/Classes/Scene3DTest/Scene3DTest.cpp +++ b/tests/cpp-tests/Classes/Scene3DTest/Scene3DTest.cpp @@ -382,7 +382,6 @@ void Scene3DTestScene::createWorld3D() _skyBox = Skybox::create(); _skyBox->setCameraMask(s_CM[LAYER_BACKGROUND]); _skyBox->setTexture(_textureCube); - _skyBox->setScale(700.f); // create terrain Terrain::DetailMap r("TerrainTest/dirt.jpg"); diff --git a/tests/js-tests/src/Sprite3DTest/Sprite3DTest.js b/tests/js-tests/src/Sprite3DTest/Sprite3DTest.js index 326c4a7d7f..7d9d4e13f0 100755 --- a/tests/js-tests/src/Sprite3DTest/Sprite3DTest.js +++ b/tests/js-tests/src/Sprite3DTest/Sprite3DTest.js @@ -1596,7 +1596,6 @@ var Sprite3DCubeMapTest = Sprite3DTestDemo.extend({ var skybox = jsb.Skybox.create(); skybox.setTexture(textureCube); this.addChild(skybox); - skybox.setScale(700); this.addChild(camera); this.setCameraMask(2); diff --git a/tests/lua-tests/src/Scene3DTest/Scene3DTest.lua b/tests/lua-tests/src/Scene3DTest/Scene3DTest.lua index da44d35f47..ef1651930c 100644 --- a/tests/lua-tests/src/Scene3DTest/Scene3DTest.lua +++ b/tests/lua-tests/src/Scene3DTest/Scene3DTest.lua @@ -349,7 +349,6 @@ function Scene3DTest:create3DWorld() self._skyBox = cc.Skybox:create() self._skyBox:setCameraMask(s_CM[GAME_LAYER.LAYER_SKYBOX]) self._skyBox:setTexture(self._textureCube) - self._skyBox:setScale(700.0) self:addChild(self._skyBox) local targetPlatform = cc.Application:getInstance():getTargetPlatform() diff --git a/tests/lua-tests/src/Sprite3DTest/Sprite3DTest.lua b/tests/lua-tests/src/Sprite3DTest/Sprite3DTest.lua index c1b86d1d6f..518b596e8b 100644 --- a/tests/lua-tests/src/Sprite3DTest/Sprite3DTest.lua +++ b/tests/lua-tests/src/Sprite3DTest/Sprite3DTest.lua @@ -1179,7 +1179,6 @@ function Sprite3DCubeMapTest:addNewSpriteWithCoords(pos) self._skyBox:setTexture(self._textureCube) self:addChild(self._skyBox) - self._skyBox:setScale(700) self:addChild(camera) self:setCameraMask(2)