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Use shaders to draw object as point (dumb version)

pull/3/head
Hleb Valoshka 2019-11-26 23:42:25 +03:00
parent a4af9e3e05
commit 539f80367f
1 changed files with 49 additions and 88 deletions
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137
src/celengine/render.cpp
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@ -3524,6 +3524,51 @@ void Renderer::draw(const Observer& observer,
#endif
}
void renderPoint(const Renderer &renderer,
const Vector3f &position,
const Color &color,
float size,
bool useSprite)
{
CelestiaGLProgram *prog;
if (useSprite)
prog = renderer.getShaderManager().getShader("star");
else
prog = renderer.getShaderManager().getShader(ShaderProperties::PerVertexColor);
if (prog == nullptr)
return;
prog->use();
prog->samplerParam("starTex") = 0;
glEnable(GL_POINT_SPRITE);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, &position);
glEnableClientState(GL_COLOR_ARRAY);
Vector4f mainColor = color.toVector4();
glColorPointer(4, GL_FLOAT, 0, &mainColor);
glEnableVertexAttribArray(CelestiaGLProgram::PointSizeAttributeIndex);
if (useSprite)
{
glVertexAttribPointer(CelestiaGLProgram::PointSizeAttributeIndex,
1, GL_FLOAT, GL_FALSE,
0, &size);
glEnable(GL_VERTEX_PROGRAM_POINT_SIZE);
}
glDrawArrays(GL_POINTS, 0, 1);
if (useSprite)
{
glDisable(GL_VERTEX_PROGRAM_POINT_SIZE);
glDisableVertexAttribArray(CelestiaGLProgram::PointSizeAttributeIndex);
}
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glDisable(GL_POINT_SPRITE);
glUseProgram(0);
}
// If the an object occupies a pixel or less of screen space, we don't
// render its mesh at all and just display a starlike point instead.
// Switching between the particle and mesh renderings of an object is
@ -3610,53 +3655,11 @@ void Renderer::renderObjectAsPoint(const Vector3f& position,
glareAlpha *= fade;
}
Matrix3f m = cameraOrientation.conjugate().toRotationMatrix();
Vector3f center = position;
// Offset the glare sprite so that it lies in front of the object
Vector3f direction = center.normalized();
// Position the sprite on the the line between the viewer and the
// object, and on a plane normal to the view direction.
center = center + direction * (radius / (m * Vector3f::UnitZ()).dot(direction));
glEnable(GL_DEPTH_TEST);
#if !defined(NO_MAX_POINT_SIZE)
// TODO: OpenGL appears to limit the max point size unless we
// actually set up a shader that writes the pointsize values. To get
// around this, we'll use billboards.
Vector3f v0 = m * Vector3f(-1, -1, 0);
Vector3f v1 = m * Vector3f( 1, -1, 0);
Vector3f v2 = m * Vector3f( 1, 1, 0);
Vector3f v3 = m * Vector3f(-1, 1, 0);
float distanceAdjust = pixelSize * center.norm() * 0.5f;
if (starStyle == PointStars)
{
glDisable(GL_TEXTURE_2D);
glBegin(GL_POINTS);
glColor(color, alpha);
glVertex(center);
glEnd();
glEnable(GL_TEXTURE_2D);
}
else
{
bool useSprites = starStyle != PointStars;
if (useSprites)
gaussianDiscTex->bind();
pointSize *= distanceAdjust;
glBegin(GL_QUADS);
glColor(color, alpha);
glTexCoord2f(0, 1);
glVertex(center + (v0 * pointSize));
glTexCoord2f(1, 1);
glVertex(center + (v1 * pointSize));
glTexCoord2f(1, 0);
glVertex(center + (v2 * pointSize));
glTexCoord2f(0, 0);
glVertex(center + (v3 * pointSize));
glEnd();
}
renderPoint(*this, position, {color, alpha}, pointSize, useSprites);
// If the object is brighter than magnitude 1, add a halo around it to
// make it appear more brilliant. This is a hack to compensate for the
@ -3667,52 +3670,10 @@ void Renderer::renderObjectAsPoint(const Vector3f& position,
if (useHalos && glareAlpha > 0.0f)
{
gaussianGlareTex->bind();
glareSize *= distanceAdjust;
glBegin(GL_QUADS);
glColor(color, glareAlpha);
glTexCoord2f(0, 1);
glVertex(center + (v0 * glareSize));
glTexCoord2f(1, 1);
glVertex(center + (v1 * glareSize));
glTexCoord2f(1, 0);
glVertex(center + (v2 * glareSize));
glTexCoord2f(0, 0);
glVertex(center + (v3 * glareSize));
glEnd();
}
#else
// Disabled because of point size limits
glEnable(GL_POINT_SPRITE);
glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE);
gaussianDiscTex->bind();
glColor(color, alpha);
glPointSize(pointSize);
glBegin(GL_POINTS);
glVertex(center);
glEnd();
// If the object is brighter than magnitude 1, add a halo around it to
// make it appear more brilliant. This is a hack to compensate for the
// limited dynamic range of monitors.
//
// TODO: Stars look fine but planets look unrealistically bright
// with halos.
if (useHalos && glareAlpha > 0.0f)
{
gaussianGlareTex->bind();
glColor(color, glareAlpha);
glPointSize(glareSize);
glBegin(GL_POINTS);
glVertex(center);
glEnd();
renderPoint(*this, position, {color, glareAlpha}, glareSize, true);
}
glDisable(GL_POINT_SPRITE);
glDisable(GL_DEPTH_TEST);
#endif // NO_MAX_POINT_SIZE
}
}