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SFML/src/SFML/Graphics/RenderTarget.cpp

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////////////////////////////////////////////////////////////
//
// SFML - Simple and Fast Multimedia Library
// Copyright (C) 2007-2009 Laurent Gomila (laurent.gom@gmail.com)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
// you must not claim that you wrote the original software.
// If you use this software in a product, an acknowledgment
// in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
// and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Graphics/RenderTarget.hpp>
#include <SFML/Graphics/Drawable.hpp>
#include <SFML/Graphics/Shader.hpp>
#include <SFML/Graphics/Texture.hpp>
#include <SFML/Graphics/VertexArray.hpp>
#include <SFML/Graphics/GLCheck.hpp>
#include <iostream>
namespace sf
{
////////////////////////////////////////////////////////////
RenderTarget::RenderTarget() :
myDefaultView(),
myView (),
myCache ()
{
}
////////////////////////////////////////////////////////////
RenderTarget::~RenderTarget()
{
}
////////////////////////////////////////////////////////////
void RenderTarget::Clear(const Color& color)
{
if (Activate(true))
{
GLCheck(glClearColor(color.r / 255.f, color.g / 255.f, color.b / 255.f, color.a / 255.f));
GLCheck(glClear(GL_COLOR_BUFFER_BIT));
}
}
////////////////////////////////////////////////////////////
void RenderTarget::SetView(const View& view)
{
myView = view;
myCache.ViewChanged = true;
}
////////////////////////////////////////////////////////////
const View& RenderTarget::GetView() const
{
return myView;
}
////////////////////////////////////////////////////////////
const View& RenderTarget::GetDefaultView() const
{
return myDefaultView;
}
////////////////////////////////////////////////////////////
IntRect RenderTarget::GetViewport(const View& view) const
{
float width = static_cast<float>(GetWidth());
float height = static_cast<float>(GetHeight());
const FloatRect& viewport = view.GetViewport();
return IntRect(static_cast<int>(0.5f + width * viewport.Left),
static_cast<int>(0.5f + height * viewport.Top),
static_cast<int>(width * viewport.Width),
static_cast<int>(height * viewport.Height));
}
////////////////////////////////////////////////////////////
Vector2f RenderTarget::ConvertCoords(unsigned int x, unsigned int y) const
{
return ConvertCoords(x, y, GetView());
}
////////////////////////////////////////////////////////////
Vector2f RenderTarget::ConvertCoords(unsigned int x, unsigned int y, const View& view) const
{
// First, convert from viewport coordinates to homogeneous coordinates
Vector2f coords;
IntRect viewport = GetViewport(view);
coords.x = -1.f + 2.f * (static_cast<int>(x) - viewport.Left) / viewport.Width;
coords.y = 1.f - 2.f * (static_cast<int>(y) - viewport.Top) / viewport.Height;
// Then transform by the inverse of the view matrix
return view.GetInverseTransform().TransformPoint(coords);
}
////////////////////////////////////////////////////////////
void RenderTarget::Draw(const Drawable& drawable, const RenderStates& states)
{
drawable.Draw(*this, states);
}
////////////////////////////////////////////////////////////
void RenderTarget::Draw(const Vertex* vertices, unsigned int vertexCount,
PrimitiveType type, const RenderStates& states)
{
// Nothing to draw?
if (!vertices || (vertexCount == 0))
return;
if (Activate(true))
{
// Check if the vertex count is low enough so that we can pre-transform them
bool useVertexCache = (vertexCount <= StatesCache::VertexCacheSize);
if (useVertexCache)
{
// Pre-transform the vertices and store them into the vertex cache
for (unsigned int i = 0; i < vertexCount; ++i)
{
Vertex& vertex = myCache.VertexCache[i];
vertex.Position = states.Transform * vertices[i].Position;
vertex.Color = vertices[i].Color;
vertex.TexCoords = vertices[i].TexCoords;
}
// Since vertices are transformed, we must use an identity transform to render them
if (!myCache.UseVertexCache)
ApplyTransform(Transform::Identity);
}
else
{
ApplyTransform(states.Transform);
}
// Apply the view
if (myCache.ViewChanged)
ApplyCurrentView();
// Apply the blend mode
if (states.BlendMode != myCache.LastBlendMode)
ApplyBlendMode(states.BlendMode);
// Apply the texture
Uint64 textureId = states.Texture ? states.Texture->myCacheId : 0;
if (textureId != myCache.LastTextureId)
ApplyTexture(states.Texture);
// Apply the shader
if (states.Shader)
ApplyShader(states.Shader);
// If we pre-transform the vertices, we must use our internal vertex cache
if (useVertexCache)
{
// ... and if we already used it previously, we don't need to set the pointers again
if (!myCache.UseVertexCache)
vertices = myCache.VertexCache;
else
vertices = NULL;
}
// Setup the pointers to the vertices' components
if (vertices)
{
const char* data = reinterpret_cast<const char*>(vertices);
GLCheck(glVertexPointer(2, GL_FLOAT, sizeof(Vertex), data + 0));
GLCheck(glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(Vertex), data + 8));
GLCheck(glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), data + 12));
}
// Find the OpenGL primitive type
static const GLenum modes[] = {GL_POINTS, GL_LINES, GL_LINE_STRIP, GL_TRIANGLES,
GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, GL_QUADS};
GLenum mode = modes[type];
// Draw the primitives
GLCheck(glDrawArrays(mode, 0, vertexCount));
// Unbind the shader, if any
if (states.Shader)
ApplyShader(NULL);
// Update the cache
myCache.UseVertexCache = useVertexCache;
}
}
////////////////////////////////////////////////////////////
void RenderTarget::PushGLStates()
{
if (Activate(true))
{
GLCheck(glPushAttrib(GL_ALL_ATTRIB_BITS));
GLCheck(glMatrixMode(GL_MODELVIEW));
GLCheck(glPushMatrix());
GLCheck(glMatrixMode(GL_PROJECTION));
GLCheck(glPushMatrix());
GLCheck(glMatrixMode(GL_TEXTURE));
GLCheck(glPushMatrix());
}
ResetGLStates();
}
////////////////////////////////////////////////////////////
void RenderTarget::PopGLStates()
{
if (Activate(true))
{
GLCheck(glPopAttrib());
GLCheck(glMatrixMode(GL_PROJECTION));
GLCheck(glPopMatrix());
GLCheck(glMatrixMode(GL_MODELVIEW));
GLCheck(glPopMatrix());
GLCheck(glMatrixMode(GL_TEXTURE));
GLCheck(glPopMatrix());
}
}
////////////////////////////////////////////////////////////
void RenderTarget::ResetGLStates()
{
if (Activate(true))
{
// Make sure that GLEW is initialized
priv::EnsureGlewInit();
// Define the default OpenGL states
GLCheck(glDisable(GL_LIGHTING));
GLCheck(glDisable(GL_DEPTH_TEST));
GLCheck(glEnable(GL_TEXTURE_2D));
GLCheck(glEnable(GL_ALPHA_TEST));
GLCheck(glEnable(GL_BLEND));
GLCheck(glAlphaFunc(GL_GREATER, 0));
GLCheck(glMatrixMode(GL_MODELVIEW));
GLCheck(glEnableClientState(GL_VERTEX_ARRAY));
GLCheck(glEnableClientState(GL_COLOR_ARRAY));
GLCheck(glEnableClientState(GL_TEXTURE_COORD_ARRAY));
// Apply the default SFML states
ApplyBlendMode(BlendAlpha);
ApplyTransform(Transform::Identity);
ApplyTexture(NULL);
if (Shader::IsAvailable())
ApplyShader(NULL);
myCache.UseVertexCache = false;
// Set the default view
SetView(GetView());
}
}
////////////////////////////////////////////////////////////
void RenderTarget::Initialize()
{
// Setup the default and current views
myDefaultView.Reset(FloatRect(0, 0, static_cast<float>(GetWidth()), static_cast<float>(GetHeight())));
myView = myDefaultView;
// Initialize the default OpenGL render-states
ResetGLStates();
}
////////////////////////////////////////////////////////////
void RenderTarget::ApplyCurrentView()
{
// Set the viewport
IntRect viewport = GetViewport(myView);
int top = GetHeight() - (viewport.Top + viewport.Height);
GLCheck(glViewport(viewport.Left, top, viewport.Width, viewport.Height));
// Set the projection matrix
GLCheck(glMatrixMode(GL_PROJECTION));
GLCheck(glLoadMatrixf(myView.GetTransform().GetMatrix()));
// Go back to model-view mode
GLCheck(glMatrixMode(GL_MODELVIEW));
myCache.ViewChanged = false;
}
////////////////////////////////////////////////////////////
void RenderTarget::ApplyBlendMode(BlendMode mode)
{
switch (mode)
{
// Alpha blending
// glBlendFuncSeparateEXT is used when available to avoid an incorrect alpha value when the target
// is a RenderTexture -- in this case the alpha value must be written directly to the target buffer
default :
case BlendAlpha :
if (GLEW_EXT_blend_func_separate)
GLCheck(glBlendFuncSeparateEXT(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA));
else
GLCheck(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));
break;
// Additive blending
case BlendAdd :
GLCheck(glBlendFunc(GL_SRC_ALPHA, GL_ONE));
break;
// Multiplicative blending
case BlendMultiply :
GLCheck(glBlendFunc(GL_DST_COLOR, GL_ZERO));
break;
// No blending
case BlendNone :
GLCheck(glBlendFunc(GL_ONE, GL_ZERO));
break;
}
myCache.LastBlendMode = mode;
}
////////////////////////////////////////////////////////////
void RenderTarget::ApplyTransform(const Transform& transform)
{
// No need to call glMatrixMode(GL_MODELVIEW), it is always the
// current mode (for optimization purpose, since it's the most used)
GLCheck(glLoadMatrixf(transform.GetMatrix()));
}
////////////////////////////////////////////////////////////
void RenderTarget::ApplyTexture(const Texture* texture)
{
if (texture)
texture->Bind(Texture::Pixels);
else
GLCheck(glBindTexture(GL_TEXTURE_2D, 0));
myCache.LastTextureId = texture ? texture->myCacheId : 0;
}
////////////////////////////////////////////////////////////
void RenderTarget::ApplyShader(const Shader* shader)
{
if (shader)
shader->Bind();
else
GLCheck(glUseProgramObjectARB(0));
}
} // namespace sf
////////////////////////////////////////////////////////////
// Render states caching strategies
//
// * View
// If SetView was called since last draw, the projection
// matrix is updated. We don't need more, the view doesn't
// change frequently.
//
// * Transform
// The transform matrix is usually expensive because each
// entity will most likely use a different transform. This can
// lead, in worst case, to changing it every 4 vertices.
// To avoid that, when the vertex count is low enough, we
// pre-transform them and therefore use an identity transform
// to render them.
//
// * Blending mode
// It's a simple integral value, so we can easily check
// whether the value to apply is the same as before or not.
//
// * Texture
// Storing the pointer or OpenGL ID of the last used texture
// is not enough; if the sf::Texture instance is destroyed,
// both the pointer and the OpenGL ID might be recycled in
// a new texture instance. We need to use our own unique
// identifier system to ensure consistent caching.
//
// * Shader
// Shaders are very hard to optimize, because they have
// parameters that can be hard (if not impossible) to track,
// like matrices or textures. The only optimization that we
// do is that we avoid setting a null shader if there was
// already none for the previous draw.
//
////////////////////////////////////////////////////////////
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