ShaderProgram.h

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/* Copyright (C) 2023 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_RENDERER_BACKEND_GL_SHADERPROGRAM
#define INCLUDED_RENDERER_BACKEND_GL_SHADERPROGRAM

#include "lib/ogl.h"
#include "lib/file/vfs/vfs_path.h"
#include "ps/containers/Span.h"
#include "ps/CStrForward.h"
#include "renderer/backend/Format.h"
#include "renderer/backend/gl/Texture.h"
#include "renderer/backend/IShaderProgram.h"

#include <map>
#include <vector>

struct CColor;
class CMatrix3D;
class CVector3D;
class CShaderDefines;
class CStrIntern;

namespace Renderer
{

namespace Backend
{

namespace GL
{

class CDevice;

class CVertexInputLayout : public IVertexInputLayout
{
public:
    CVertexInputLayout(CDevice* device, const PS::span<const SVertexAttributeFormat> attributes)
        : m_Device(device), m_Attributes(attributes.begin(), attributes.end())
    {
        for (const SVertexAttributeFormat& attribute : m_Attributes)
        {
            ENSURE(attribute.format != Format::UNDEFINED);
            ENSURE(attribute.stride > 0);
        }
    }

    ~CVertexInputLayout() override = default;

    IDevice* GetDevice() override;

    const std::vector<SVertexAttributeFormat>& GetAttributes() const noexcept { return m_Attributes; }

private:
    CDevice* m_Device = nullptr;

    std::vector<SVertexAttributeFormat> m_Attributes;
};

/**
 * A compiled vertex+fragment shader program.
 * The implementation may use GL_ARB_{vertex,fragment}_program (ARB assembly syntax)
 * or GL_ARB_{vertex,fragment}_shader (GLSL), or may use hard-coded fixed-function
 * multitexturing setup code; the difference is hidden from the caller.
 *
 * Texture/uniform IDs are typically strings, corresponding to the names defined in
 * the shader .xml file. Alternatively (and more efficiently, if used very frequently),
 * call GetBindingSlot and pass its return value as the ID.
 * Setting uniforms that the shader .xml doesn't support is harmless.
 *
 * For a high-level overview of shaders and materials, see
 * http://trac.wildfiregames.com/wiki/MaterialSystem
 */
class CShaderProgram : public IShaderProgram
{
    NONCOPYABLE(CShaderProgram);

public:
    typedef CStrIntern attrib_id_t;

    static std::unique_ptr<CShaderProgram> Create(
        CDevice* device, const CStr& name, const CShaderDefines& baseDefines);

    ~CShaderProgram() override;

    /**
     * Binds the shader into the GL context. Call this before calling Uniform()
     * or trying to render with it.
     */
    virtual void Bind(CShaderProgram* previousShaderProgram) = 0;

    /**
     * Unbinds the shader from the GL context. Call this after rendering with it.
     */
    virtual void Unbind() = 0;

    struct TextureUnit
    {
        GLenum type;
        GLenum target;
        GLint unit;
    };
    virtual TextureUnit GetTextureUnit(const int32_t bindingSlot) = 0;

    virtual void SetUniform(
        const int32_t bindingSlot,
        const float value) = 0;
    virtual void SetUniform(
        const int32_t bindingSlot,
        const float valueX, const float valueY) = 0;
    virtual void SetUniform(
        const int32_t bindingSlot,
        const float valueX, const float valueY,
        const float valueZ) = 0;
    virtual void SetUniform(
        const int32_t bindingSlot,
        const float valueX, const float valueY,
        const float valueZ, const float valueW) = 0;
    virtual void SetUniform(
        const int32_t bindingSlot, PS::span<const float> values) = 0;

    // Vertex attribute pointers (equivalent to glVertexPointer etc).
    virtual void VertexAttribPointer(
        const VertexAttributeStream stream, const Format format,
        const uint32_t offset, const uint32_t stride,
        const VertexAttributeRate rate, const void* data);

    bool IsStreamActive(const VertexAttributeStream stream) const;

    /**
     * Checks that all the required vertex attributes have been set.
     * Call this before calling Draw/DrawIndexed etc to avoid potential crashes.
     */
    void AssertPointersBound();

protected:
    CShaderProgram(int streamflags);

    void VertexPointer(const Renderer::Backend::Format format, GLsizei stride, const void* pointer);
    void NormalPointer(const Renderer::Backend::Format format, GLsizei stride, const void* pointer);
    void ColorPointer(const Renderer::Backend::Format format, GLsizei stride, const void* pointer);
    void TexCoordPointer(GLenum texture, const Renderer::Backend::Format format, GLsizei stride, const void* pointer);

    int m_StreamFlags;

    // Non-GLSL client state handling:
    void BindClientStates();
    void UnbindClientStates();
    int m_ValidStreams; // which streams have been specified via VertexPointer etc since the last Bind
};

} // namespace GL

} // namespace Backend

} // namespace Renderer

#endif // INCLUDED_RENDERER_BACKEND_GL_SHADERPROGRAM