src/gpu/gl/GrGLProgram.h

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#ifndef GrGLProgram_DEFINED
#define GrGLProgram_DEFINED

#include "GrGLContext.h"
#include "GrProgramDesc.h"
#include "GrGLTexture.h"
#include "GrGLProgramDataManager.h"
#include "glsl/GrGLSLProgramDataManager.h"
#include "glsl/GrGLSLUniformHandler.h"

#include "SkString.h"
#include "SkXfermode.h"

#include "builders/GrGLProgramBuilder.h"

class GrGLInstalledProcessors;
class GrGLProgramBuilder;
class GrPipeline;

/**
 * This class manages a GPU program and records per-program information.
 * We can specify the attribute locations so that they are constant
 * across our shaders. But the driver determines the uniform locations
 * at link time. We don't need to remember the sampler uniform location
 * because we will bind a texture slot to it and never change it
 * Uniforms are program-local so we can't rely on fHWState to hold the
 * previous uniform state after a program change.
 */
class GrGLProgram : public SkRefCnt {
public:
    typedef GrGLSLProgramBuilder::BuiltinUniformHandles BuiltinUniformHandles;

    ~GrGLProgram();

    /**
     * Call to abandon GL objects owned by this program.
     */
    void abandon();

    const GrProgramDesc& getDesc() { return fDesc; }

    /**
     * Gets the GL program ID for this program.
     */
    GrGLuint programID() const { return fProgramID; }

    /**
     * We use the RT's size and origin to adjust from Skia device space to OpenGL normalized device
     * space and to make device space positions have the correct origin for processors that require
     * them.
     */
    struct RenderTargetState {
        SkISize         fRenderTargetSize;
        GrSurfaceOrigin fRenderTargetOrigin;

        RenderTargetState() { this->invalidate(); }
        void invalidate() {
            fRenderTargetSize.fWidth = -1;
            fRenderTargetSize.fHeight = -1;
            fRenderTargetOrigin = (GrSurfaceOrigin) -1;
        }

        /**
         * Gets a vec4 that adjusts the position from Skia device coords to GL's normalized device
         * coords. Assuming the transformed position, pos, is a homogeneous vec3, the vec, v, is
         * applied as such:
         * pos.x = dot(v.xy, pos.xz)
         * pos.y = dot(v.zw, pos.yz)
         */
        void getRTAdjustmentVec(float* destVec) {
            destVec[0] = 2.f / fRenderTargetSize.fWidth;
            destVec[1] = -1.f;
            if (kBottomLeft_GrSurfaceOrigin == fRenderTargetOrigin) {
                destVec[2] = -2.f / fRenderTargetSize.fHeight;
                destVec[3] = 1.f;
            } else {
                destVec[2] = 2.f / fRenderTargetSize.fHeight;
                destVec[3] = -1.f;
            }
        }
    };

    /**
     * This function uploads uniforms, calls each GrGL*Processor's setData, and retrieves the
     * textures that need to be bound on each unit. It is the caller's responsibility to ensure
     * the program is bound before calling, and to bind the outgoing textures to their respective
     * units upon return. (Each index in the array corresponds to its matching GL texture unit.)
     */
    void setData(const GrPrimitiveProcessor&, const GrPipeline&);

    /**
     * This function retrieves the textures that need to be used by each GrGL*Processor, and
     * ensures that any textures requiring mipmaps have their mipmaps correctly built.
     */
    void generateMipmaps(const GrPrimitiveProcessor&, const GrPipeline&);

protected:
    typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
    typedef GrGLProgramDataManager::UniformInfoArray UniformInfoArray;
    typedef GrGLProgramDataManager::VaryingInfoArray VaryingInfoArray;

    GrGLProgram(GrGLGpu*,
                const GrProgramDesc&,
                const BuiltinUniformHandles&,
                GrGLuint programID,
                const UniformInfoArray& uniforms,
                const UniformInfoArray& samplers,
                const VaryingInfoArray&, // used for NVPR only currently
                GrGLSLPrimitiveProcessor* geometryProcessor,
                GrGLSLXferProcessor* xferProcessor,
                const GrGLSLFragProcs& fragmentProcessors);

    // A helper to loop over effects, set the transforms (via subclass) and bind textures
    void setFragmentData(const GrPrimitiveProcessor&, const GrPipeline&, int* nextSamplerIdx);

    // Helper for setData() that sets the view matrix and loads the render target height uniform
    void setRenderTargetState(const GrPrimitiveProcessor&, const GrPipeline&);

    // Helper for setData() that binds textures and texel buffers to the appropriate texture units
    void bindTextures(const GrProcessor&, bool allowSRGBInputs, int* nextSamplerIdx);

    // Helper for generateMipmaps() that ensures mipmaps are up to date
    void generateMipmaps(const GrProcessor&, bool allowSRGBInputs);

    // these reflect the current values of uniforms (GL uniform values travel with program)
    RenderTargetState fRenderTargetState;
    BuiltinUniformHandles fBuiltinUniformHandles;
    GrGLuint fProgramID;

    // the installed effects
    std::unique_ptr<GrGLSLPrimitiveProcessor> fGeometryProcessor;
    std::unique_ptr<GrGLSLXferProcessor> fXferProcessor;
    GrGLSLFragProcs fFragmentProcessors;

    GrProgramDesc fDesc;
    GrGLGpu* fGpu;
    GrGLProgramDataManager fProgramDataManager;

    friend class GrGLProgramBuilder;

    typedef SkRefCnt INHERITED;
};

#endif