悬浮的形体
七年级课堂中，我们探讨了“形”与“体”、“光”与“影”、明度、明暗法（Chiaroscuro）及艺术中的布光。核心课题是在二维平面上营造体积感与纵深感。我们重点分析了阴影——包括光源位置、投影（cast shadow）与形体阴影（form shadow），并学习了三种不同表现方式的明暗法绘制方法。所有这些知识点最终整合于一幅综合媒材绘画作品《悬浮的形体》之中。
首先，我们在若干几何立体上绘制形体阴影。你可以手绘这些立体，也可直接下载下方提供的可打印PDF模板。
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我们设定光源位于左上方，随后绘制形体阴影。我们运用三种不同的明暗表现技法：通过控制铅笔压力变化实现明暗过渡、交叉排线（crosshatching）以及揉擦法（scumbling）。
接着，我们在素描纸上绘制某一种颜色的明度色阶。我们使用蛋彩颜料（tempera）：起始为最浅色调（大量白色混入极少量纯色）；随后逐步增加纯色比例，用平头画笔快速作画，并在纸面直接调和颜料（趁其未干时）；在色阶最深部分，加入少量黑色，以获得更深的色调。
待绘制的背景色完全干燥后，我们将已画好明暗的立体形剪下，随机粘贴于画面上。视觉效果仿佛画中的立体形正悬浮于空中，或缓缓自上方坠落。
本综合媒材创作的最后一步，是在立体形下方的白色底面上绘制投影。
In the 7th Grade classes we spoke about Shape and Forms, Light and Shadows and Value, Chiaroscuro and Lighting in Art. The main topic was about creating the sense of volume and depth on a 2-dimensional surface. We analyzed the topic of shadows with the light source, the cast and the form shadow and how to draw three different kinds of Chiaroscuro. All these topics were summarized in a mixed media painting with “floating forms”.
First we drew the form shadows on some solids. You can draw the solids but you can also buy the template of these solids in a printable pdf format here below.
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We choose the source of light (up left) and then we drew the form shadows. We used three different ways of shading drawing three kinds of Chiaroscuro: shading changing the pressure of the pencil, crosshatching and scumbling.
After that we painted a value scale of a color on a drawing sheet. We used tempera paint, starting from the lighter color ( big amount of white with a small amount of a pure color). Then we added the pure color a little at a time, painting fast with flat paintbrushes and mixing the colors on the paper, before they dry. In the last part of value scale we added a small amount of black, in order to obtain darker colors.
When the painted background was dry we cut out the shaded forms and we paste them on the painting randomly. The visual effect would be as if the forms in the painting seem to float or fall slowly from above.
In the last step of this mixed media work we drew the cast shadows on the white surface below the solids.