A complete wireframe debug renderer for Oryol

Wireframe.cc

//------------------------------------------------------------------------------
//  Wireframe.cc
//------------------------------------------------------------------------------
#include "Pre.h"
#include "Wireframe.h"
#include "Gfx/Gfx.h"
#include "shaders.h"

namespace Oryol {

//------------------------------------------------------------------------------
void
Wireframe::Setup(const GfxSetup& gfxSetup) {
    Gfx::PushResourceLabel();
    auto meshSetup = MeshSetup::Empty(MaxNumVertices, Usage::Stream);
    meshSetup.Layout = {
        { VertexAttr::Position, VertexFormat::Float3 },
        { VertexAttr::Color0, VertexFormat::Float4 }
    };
    this->drawState.Mesh[0] = Gfx::CreateResource(meshSetup);

    Id shd = Gfx::CreateResource(WireframeShader::Setup());
    auto pipSetup = PipelineSetup::FromLayoutAndShader(meshSetup.Layout, shd);
    pipSetup.RasterizerState.SampleCount = gfxSetup.SampleCount;
    pipSetup.BlendState.ColorFormat = gfxSetup.ColorFormat;
    pipSetup.BlendState.DepthFormat = gfxSetup.DepthFormat;
    pipSetup.PrimType = PrimitiveType::Lines;
    this->drawState.Pipeline = Gfx::CreateResource(pipSetup);
    this->label = Gfx::PopResourceLabel();
}

//------------------------------------------------------------------------------
void
Wireframe::Discard() {
    Gfx::DestroyResources(this->label);
}

//------------------------------------------------------------------------------
void
Wireframe::Line(const glm::vec4& p0, const glm::vec4& p1) {
    if ((this->vertices.Size() + 2) < MaxNumVertices) {
        this->vertices.Add(this->Model * p0, this->Color);
        this->vertices.Add(this->Model * p1, this->Color);
    }
}

//------------------------------------------------------------------------------
void
Wireframe::Line(const glm::vec3& p0, const glm::vec3& p1) {
    this->Line(glm::vec4(p0, 1.0f), glm::vec4(p1, 1.0f));
}

//------------------------------------------------------------------------------
void
Wireframe::Rect(const glm::vec3& p0, const glm::vec3& p1, const glm::vec3& p2, const glm::vec3& p3) {
    this->Line(p0, p1); this->Line(p1, p2); this->Line(p2, p3); this->Line(p3, p0);
}

//------------------------------------------------------------------------------
void
Wireframe::Render() {
    if (!this->vertices.Empty()) {
        Gfx::UpdateVertices(this->drawState.Mesh[0], this->vertices.begin(), this->vertices.Size()*sizeof(Vertex));
        Gfx::ApplyDrawState(this->drawState);
        WireframeShader::vsParams vsParams;
        vsParams.viewProj = this->ViewProj;
        Gfx::ApplyUniformBlock(vsParams);
        Gfx::Draw({ 0, this->vertices.Size() });
        /** oops, don't forget to reset the vertices array :) **/
        this->vertices.Reset();
    }
}

} // namespace Oryol

Wireframe.h

#pragma once
//------------------------------------------------------------------------------
/**
    @class Wireframe
    @brief simple wireframe debug renderer
*/
#include "Gfx/Gfx.h"
#include "Core/Containers/InlineArray.h"
#include <glm/mat4x4.hpp>
#include <glm/vec3.hpp>
#include <glm/vec4.hpp>

namespace Oryol {

struct Wireframe {
    
    /// set this to the current ViewProj matrix
    glm::mat4 ViewProj;
    /// set this to the current model matrix
    glm::mat4 Model;
    /// set this to the current line color
    glm::vec4 Color = glm::vec4(1.0f, 1.0f, 1.0f, 1.0f);

    /// setup the debug renderer
    void Setup(const GfxSetup& setup);
    /// discard the debug renderer
    void Discard();
    /// call once before Gfx::CommitFrame to render the debug scene
    void Render();
    /// add a wireframe line (vec3)
    void Line(const glm::vec3& p0, const glm::vec3& p1);
    /// add a wireframe line (vec4, w must be 1)
    void Line(const glm::vec4& p0, const glm::vec4& p1);
    /// add a rectangle (vec3)
    void Rect(const glm::vec3& p0, const glm::vec3& p1, const glm::vec3& p2, const glm::vec3& p3);

    DrawState drawState;
    ResourceLabel label;
    struct Vertex {
        float x, y, z, r, g, b, a;
        Vertex() { };
        Vertex(const glm::vec4& p, const glm::vec4& c):
            x(p.x), y(p.y), z(p.z), r(c.x), g(c.y), b(c.z), a(c.w) { };
    };
    static const int MaxNumVertices = 4096;
    InlineArray<Vertex, MaxNumVertices> vertices;
};

}

Wireframe.shd

@vs wireframeVS
uniform vsParams {
    mat4 viewProj;
};
in vec4 position;
in vec4 color0;
out vec4 color;
void main() {
    gl_Position = viewProj * position;
    color = color0;
}
@end

@fs wireframeFS
in vec4 color;
out vec4 fragColor;

void main() {
    fragColor = color;
}
@end

@program WireframeShader wireframeVS wireframeFS