Support rendering compute shaders straight to textures (skipping the dummy phase).

[movit] / effect_chain.h

diff --git a/effect_chain.h b/effect_chain.h
index 038fb1c875e282616db5d2193ea02ade2cfad958..35931f8058fb1a7d763fdb7572ccd2f94bb4d945 100644 (file)
--- a/effect_chain.h
+++ b/effect_chain.h
@@ -389,6 +389,22 @@ public:
        // the current viewport.
        void render_to_fbo(GLuint fbo, unsigned width, unsigned height);
 
+       // Render the effect chain to the given set of textures. This is equivalent
+       // to render_to_fbo() with a freshly created FBO bound to the given textures,
+       // except that it is more efficient if the last phase contains a compute shader.
+       // Thus, prefer this to render_to_fbo() where possible.
+       //
+       // The format must currently be GL_RGBA16F, and only one destination
+       // texture is supported. Both of these restrictions will be lifted in the future.
+       //
+       // All destination textures must be exactly of size <width> x <height>.
+       // width and height can not be zero.
+       struct DestinationTexture {
+               GLuint texnum;
+               GLenum format;
+       };
+       void render_to_texture(const std::vector<DestinationTexture> &destinations, unsigned width, unsigned height);
+
        Effect *last_added_effect() {
                if (nodes.empty()) {
                        return nullptr;
@@ -457,6 +473,13 @@ private:
        // as the last effect. Also pushes all phases in order onto <phases>.
        Phase *construct_phase(Node *output, std::map<Node *, Phase *> *completed_effects);
 
+       // Do the actual rendering of the chain. If <dest_fbo> is not (GLuint)-1,
+       // renders to that FBO. If <destinations> is non-empty, render to that set
+       // of textures (last phase, save for the dummy phase, must be a compute shader),
+       // with x/y ignored. Having both set is an error.
+       void render(GLuint dest_fbo, const std::vector<DestinationTexture> &destinations,
+                   unsigned x, unsigned y, unsigned width, unsigned height);
+
        // Execute one phase, ie. set up all inputs, effects and outputs, and render the quad.
        void execute_phase(Phase *phase, bool render_to_texture,
                           std::map<Phase *, GLuint> *output_textures,
@@ -539,6 +562,12 @@ private:
        bool finalized;
        GLuint vbo;  // Contains vertex and texture coordinate data.
 
+       // Whether the last effect (which will then be in a phase all by itself)
+       // is a dummy effect that is only added because the last phase uses a compute
+       // shader, which cannot output directly to the backbuffer. This means that
+       // the phase can be skipped if we are _not_ rendering to the backbuffer.
+       bool has_dummy_effect = false;
+
        ResourcePool *resource_pool;
        bool owns_resource_pool;